CHAPTER 3

Directed Energy Weapons

Directed energy weapons (DEWs), the ability to project destructive energy without the need for a physical projectile, has been on the emerging technology horizon for decades, if not since antiquity. There is persistent debate over whether Archimedes of Syracuse (287–212 BC) constructed a solar-focusing weapon. H. G. Wells's 1898 science fiction classic, The War of the Worlds, had mention of heat rays employed by the technologically superior invaders from Mars. During the interwar period, early radar work in the United Kingdom was linked to research over the feasibility of a radio “death ray.” In the 1980s, various DEW concepts were investigated under the Strategic Defense Initiative (SDI), a comprehensive plan to find a defense against large-scale intercontinental ballistic missile (ICBM) attack. Recent efforts include goals such as shooting down rocket, artillery, and mortars (RAM) threats and igniting improvised explosive devices (IEDs). Though lacking the ambition of past DEW concepts, the capabilities being demonstrated today are perhaps finally heralding the transition of DEW from a promising emerging military technology to practical battlefield systems.

Along with beams of fantastical destructive power, DEW technology also promises less-than-lethal coercive effects. There has been a growing desire to give soldiers and law enforcement a stun weapon, something common in science fiction. Many direct energy weapon concepts include variable effects, allowing operators to tailor effects to only what is appropriate to a particular situation. A component of the last Revolution in Military Affairs was increased precision, lowering the investment in force and collateral damage needed to accomplish a task. DEW technology has the potential to take precision to new levels, the ability to not just target individual troublemakers in a crowd, but to apply only enough force to change their actions. Now although this clean and bloodless vision may seem overly optimistic, the promise of this capability does fit into some perceptions and desires over how military force can and should be used by the West.

Although DEWs promise much, the inescapable reality is that these concepts have been around for quite some time without much in the way of tangible products. The problems can be divided into categories based on the components of the term DEW—there are challenges to reliably direct the energies involved, challenges to generating the energies in the correct form, and challenges in producing effects on the target to make these systems actually weapons. Technical challenges translate into large planned, and many unplanned, financial costs for programs seeking to create a practical DEW. The perceived newness of DEW technology, and skepticism brought on by awareness of past failures, present additional roadblocks to these systems being accepted. DEWs may represent a redundant capability that, outside of a few niche applications, has quite far to go before matching bullets and warheads in general military utility. With the severe budgetary constraints faced by the United States and others in the second decade of the 21st century, there will be great competition, and outright opposition from within the defense establishment.

There is also resistance brought on by concerns that these systems may have unintended or undisclosed effects; in particular, concerns over the potential for less-than-lethal DEW capabilities to be abused. A weapon that does not kill to achieve effectiveness is not only useful in the prevention of unnecessary death, but the capacity of DEW in the wrong hands to torture and maim also presents serious concerns over proliferation to nations with questionable human rights records. Accidental misuse could also stem from overuse due to less-than-lethal weapons not being handled with the same caution and gravity as traditional killing weapons. Perceptions on the “legality,” and sentiments on how “humane” a weapon is or should be, may overshadow any real obligations a nation may have concerning a particular weapon system. Rightly or wrongly weapon concepts do acquire stigmas that can limit any opportunities they have for demonstrating their utility, including that of preventing unnecessary casualties, on real battlefields.

Energy and Energy Weapons

Energy is the capacity to do work, to produce change in a physical system. An energy weapon is a weapon that performs some manner of physical change, considered of a destructive nature, without the benefit of a physical projectile or container. The cliché energy weapons portrayed in the media are those that transmit destructive powers via electromagnetic (EM) radiation, usually in the form of beams of visible light. In reality, most proposed weapons based on EM radiation use parts of the spectrum invisible to the human eye. Indeed most of the EM spectrum is not perceivable by the human eye, ranging from many-meters-long wavelength radio waves, to very high-energy gamma rays that have wavelengths smaller than an atom. Unlike other waves that need a medium such as sound, EM waves can propagate without a physical medium. Indeed EM energy propagates best in a total vacuum, as interactions with matter may impede or distort the transmission.

Light, and EM radiation in general, can be considered as both a wave and as a particle—a wave-particle duality. The photon is this elementary particle of light, a mass-less packet of energy. Some interactions and phenomena of light, such as diffusion, can be considered and easily explained by wave theory. Other aspects of light, such as many elements of laser physics, require a particle understanding of light. A comprehensive understanding of light (i.e., quantum mechanics) requires this dual wave and particle nature of light.

Related to, but distinct from, the weaponizaion of the EM spectrum is the particle beam, the use of atoms and the components of atoms, projected to a distance at speeds near to the speed of light, to provide a destructive effect. Though minute, the particles of a particle beam have mass. Like many of the technologies discussed in this chapter, low-power particle beams are in widespread use today. The cathode ray tube (CRT), found in older televisions and computer monitors, are built around an electronically aimed particle beam firing at a screen to produce light. Low-power particle beams are already used to sterilize food and medical equipment. At much higher-energy levels is natural ionizing radiation, which is in part made up of fast-moving atomic particles (the rest of it being high-energy EM radiation). The destructive effects of natural lightning, the passage of large quantities of charged particles through the air, provides inspiration for the concept, though not necessarily a means, of artificially generating these levels of energy, or providing the precision needed for a weapon. A weapon, unlike lightning, must be able to hit the same place as many times as commanded.

Particle beams were considered as missile defense weapons during early SDI research. Of particular interest was the neutral particle beam. The earth's magnetic field regularly deflects and traps high-energy particles from external sources, such as the sun, meaning that it would also deflect the beam of a charged particle weapon. A neutral particle beam produces a particle beam with no net charge, meaning it wouldn't be affected by the earth's magnetic field. A charged particle beam would also interfere with itself due to like charges repelling each other. A stream of charged particles would have a tendency to disperse due to being composed of elementary particles of one charge. This, however, adds the problem of how to neutralize the charge of a high-energy particle beam to the problems of generating such a beam in the first place. Later SDI research concentrated on kinetic-energy interceptors and the space-based laser (SBL) concepts as being nearer-term capabilities.

Lasers Part I: Basics

The development of the laser and related devices brought DEWs closer to plausibility. Light amplification by stimulated emission of radiation, or LASER, is an effect predicted by quantum physics in the early 20th century by Albert Einstein. The laser as a device became a demonstrated reality in 1960¹ and is generally credited to Dr. Theodore H. Maiman, although there is some dispute over this first laser, as well the place of earlier patents and scientific papers from the late 1950s concerning the specifics for a laser device before someone actual managed to build one.² The light component of the acronym would imply a device that produced EM radiation visible to the human eye, but the nomenclature has expanded to cover many devices that use the same science to produce other wavelengths of EM radiation. Based on the same physics, the microwave amplification by stimulated emission of radiation (MASER), basically a laser operating on the microwave portion of the spectrum was actually demonstrated earlier in 1954 by Dr. Charles Townes.³ A MASER can also be called a microwave laser, and similarly a laser operating at the gamma-ray end of the EM spectrum, can be referred to as a GASER or GRASER.

The light that emerges from a laser is coherent. Critically for weapon applications, this means that all the photons of light are travelling in parallel. The unprecedented straightness of a laser beam has led to it being used as the very definition of direction in surveying, industry, science, as well as in defense applications. Measurements by lasers aimed at reflectors left behind by the U.S. Apollo moon missions are still used today for lunar research. Diffraction sets a fundamental limit on how far a particular wavelength of EM energy can be focused, leading to the more practical statement that a laser beam does not spread out very much over a useful distance, depending on how one defines useful distance. Shorter wavelengths of light will lose focus over longer distances. How tightly a laser can be focused, in other words the laser's practical range, is referred to as its “beam quality.”⁴ Not all laser technologies are suitable for weapons use due to inherent beam-quality issues. Specifically for discussions on laser weapons, the term high-energy laser (HEL) generally refers to a laser that combines both high-energy levels and an ability to focus such energies at militarily useful ranges.

In most lasers, coherent light is amplified in a substance referred to as the gain, or lasing, medium. Depending on the specifics of the laser, this gain medium may be a solid, a gas, or a liquid. Molecules of the gain medium are excited, that is, raised to a higher-quantum energy state. Specifically the electrons of the molecule are raised to a higher-energy level, with the particulars of the molecule defining higher-energy states. Energy states are discrete levels, there is no gradual increase or decrease, and an electron in an atom or molecule is always at a particular energy level, never in between the energy levels defined by the atom or molecule. When a photon of light interacts with an excited molecule of the gain medium the molecule returns to a lower-energy level, emitting the lost energy as a photon that is travelling in the same direction and phase as the first; the molecule has been stimulated into emitting a photon of light that is essentially of the same nature of the first photon. Of note is that the quantity of extra energy possessed by a molecule or atom in an excited state is the same quantity found in the emitted photon, which is the same as that possessed by the photon that triggered the release of energy. Therefore the wavelength, or type of light, produced by a laser is directly related to the particulars of the lasing medium.

Now in an actual device there are many millions of molecules that make up the gain medium, and these molecules must be in an excited state to be useful. The process for raising the molecules or atoms of the gain material into an excited state is called “pumping.” Energy for pumping a lasing medium can come from direct electrical discharge, noncoherent light, another laser, chemical reactions, and nuclear reactions. Small semiconductor lasers, such as those found in DVD players, use milliwatts of electrical power. The nuclear bomb-pumped X-ray laser of SDI fame and controversy is envisioned as being able to direct a fraction of the power of nuclear explosion into a very powerful laser output before it is consumed by its power source.

At the point where there are more excited molecules in a gain medium than those in a grounded state, termed population inversion, stimulated emission results in a net amplification of light. Different materials have different limits on how much energy is required to reach this state and how much energy will actually smother the process. Most lasers are constructed for specific roles, with the energy source and gain medium determining output characteristics, including maximum power. The very first laser used a solid ruby crystal to generate a visible laser output. Successive generations of tiny semiconductor diode lasers produce first infrared, then visible red, and finally blue laser outputs needed for compact disk, DVD, and Blue-Ray technologies, respectively. Carbon dioxide and other gases are pumped by external power sources to produce lasers used for very short-range cutting and burning for medical and industrial applications. Chemical reactions generate a stream of excited molecules to be the lasing medium in many recent HEL weapon demonstrators.

With most lasers the gain medium is inside an optical resonator, with two mirrors or other means to reflect photons back and forth through the gain medium, stimulating the emissions of more similar photons, and building up strength until the light energy is released. In a mirror-based optical resonator one mirror is partially transparent to allow some of the generated light to emerge. The fiber laser is a major exception, and instead uses the same optical properties that allow a light signal to follow a winding fiber optic cable to bounce the photons repeatedly through a lasing medium in the core of the fiber. This configuration is of interest due to the flexible nature of fiber optics technology (relative to other optics), which allows greater freedom in a laser system's layout. Key to all HEL systems is high-quality optics that minimize absorption of the generated light, such absorption resulting in both loss of efficiency and damage to the laser itself.

The free electron laser (FEL) dispenses with a physical gain medium, instead using an electron particle beam that is manipulated by magnets into emitting a laser beam. There is no lasing medium per se as the electrons are subatomic particles. Magnets manipulating a high-energy electron beam cause the electrons to release energy in the form of photons. The nature of the photons released is defined by the input electron beam and the magnetic fields, resulting in a laser output. Through control of the magnets and the initial electron beam, the output laser can be varied in wavelength, meaning one device is capable of having its output “tuned” for specific applications and situations. The capacity for “tuning” the FEL output, as well as being powered purely by electricity, have resulted in this technology being described as the “holy grail” for laser weapons development. FEL technology is described as having “inherently high beam quality,”⁵ meaning immediate potential for military ranges. For a long time, the U.S. Navy has been interested in an FEL-based defensive weapon due to the maritime environment causing great variability in the best wavelength for allowing laser energy to propagate.⁶

Since their invention, lasers have steadily found new applications. Among the most critical to modern life are lasers as tools of measurement, allowing for the precision necessary for many large-scale engineering and construction projects. These civilian-world applications are not too far removed from the military's use of lasers for weapons’ guidance; the most precise munitions guidance systems are still based around seeking a dot of reflected laser light painted onto a target by a laser designator.⁷ Like radar applications of the EM spectrum, lasers have proven useful as force multipliers. Advances since the Vietnam War have made such systems more reliable, lighter, and cheaper, but the principle remains the same.

A more sophisticated, but still broadly similar, use of laser technology is as the illumination source for light detection and ranging (LIDAR) and laser detection and ranging (LADAR) sensors. Beyond the simple LIDAR speed-measurement devices used to enforce speed limits domestically, are LIDAR and LADAR sensors capable of generating three-dimensional representations of objects. For robotics, such as the autonomous vehicles that competed in the three Defense Advanced Research Projects Agency (DARPA) Challenges,⁸ LIDAR sensors were a common means to give these robots a view of the environment they were attempting to drive in. The capacity for LIDAR technology to obtain accurate data on the shape of objects is also useful as a means of target discrimination—a tank is of a different shape than say a minibus, and with high-enough resolution, different models of tanks may be discernable by LIDAR sensors.

Laser-guided weapons still rely on explosives and kinetic energy for a destructive mechanism. Though they have eye safety warnings, most lasers in operational use today are of relatively low power. Laser technology has yet to be employed, as casual futurists have been predicting, as a materially destructive weapon system.⁹ However, the concept of an HEL weapon is an old one, and work on turning the laser into a weapon continues.

Lasers Part II: Stand-Ins and False Starts

Presently, gas dynamic laser technology represents the most advanced of HEL technology in terms of high-energy levels and beam quality needed for a weapon, but at the same time does not necessarily represent the best technology for a weapon. Gas dynamic lasers have demonstrated the capacity to generate multimegawatt energy levels. They have also demonstrated the ability to generate these high-energy outputs at wavelengths that facilitate effective energy delivery to tactically and even strategically useful distances. Finally, their effectiveness has been demonstrated outside of “clean-room” laboratory conditions. Two recent gas dynamic laser programs noted for their direct potential as fielded capabilities are the U.S. Airborne Laser (ABL) program and the joint U.S.-Israeli Tactical HEL (THEL). While providing quite a bit of research on HEL weapon technology, these programs also highlight many of the obstacles to using gas dynamic lasers as battlefield weapons.

The ABL uses a multimodule chemical oxygen iodine laser (COIL). Inside each COIL module, a chemical reaction and supersonic expansion nozzles generate energetic oxygen molecules, which in turn excite iodine molecules. These excited iodine molecules form the lasing medium and produce invisible infrared light. This high-velocity flow can be scaled up to produce megawatts of laser energy, while carrying away destructive waste heat. Several years of research spread over multiple ABL programs and a troubled development phase, culminating in the U.S. Missile Defense Agency's YAL-1A Airborne Laser Test Bed (ALTB), a converted 747 freighter containing six COIL modules, along with the optics train needed to aim the multimegawatt laser beam, including apparatus to detect and compensate for real-world atmospheric distortions, and onboard fire-control system. On February 11, 2010, the ALTB demonstrated its ability to destroy a ballistic missile while in flight (both ALTB and target missile).¹⁰ Before the program was curtailed in 2009 to one research aircraft¹¹ there was even some discussion on a small fleet of operational versions of the YAL-1A. Aside from severe fiscal constraints in 2009 and subsequent years, and the YAL-1A program being several years behind schedule, Defense Secretary Robert Gates noted other “significant”¹² technical issues with the concept in his April 6, 2009, presentation on the 2010 defense budget. Among the criticisms leveled against the idea of directly turning the YAL-1A into an operational warplane is the low range of the so-far developed HEL system, thought to be only several hundreds of kilometers.

The common mission envisioned for the ABL program in its many guises over the years, is the boost phase destruction of ballistic missile targets. A ballistic missiles flight, for the purposes of missile defense, is divided into three phases or components: boost, midcourse, and terminal. During the boost phase, the missile's propulsion is firing, which importantly for missile defense means: (1) the missile is still accelerating to the velocity needed for a ballistic trajectory to deliver warheads and (2) the rocket propulsion provides an easily detected and tracked heat signature. Politically, the missile also may have the benefit of not being over the target nation yet; with less-sophisticated threats, the missile is still over the offending nation, meaning that missile destruction minimizes endangering the “innocent.”

A laser weapon is applicable to boost phase missile defense on many fronts. First, the beam is travelling at the speed of light; therefore, as long as the beam connects, the attack is practically instant at the ranges being considered. This then leads to the possibility of rapidly shifting to other targets, or re-attacking if the first attack was insufficient. Now for a laser weapon to be an effective boost phase defense, its range and ability to deliver energy must be considered. Unlike a physical interceptor missile, such as those used by the U.S. Navy, which takes time to reach the target, but have a reasonably immediate effect on striking the target, the destructive effects of these initial HEL weapons require some exposure, or “dwell,” time. In the ABL, the “kill mechanism” is simply the laser heating a small patch of the missile's exterior to the point where the skin or the structure fails. Rocketry in general is noted for its relative fragility, and anything that takes a missile out of its operating envelope, such as a weakened structure or severely distorted skin, would result in its destruction. Liquid-fuelled rocketry is considered to be more fragile than its solid-fuelled counterparts; however, the relative sturdiness of solid-fuelled targets can be accounted for by increasing power margins, or the time the laser dwells on the target. The subject of lethality highlights the fact that simply achieving a multimegawatt power levels for a laser is insufficient for it to be directly employed as a destructive weapon.

A megawatt-class laser power only brings the potential for target destruction. To be an effective weapon, the laser must be able to deliver enough energy to achieve a destructive effect quickly enough to justify its use over a physical attack. Given a high-enough rate of energy delivery, rapid heating of solid metal becomes rapid conversion to vapor or even superheated plasma—in effect an explosion; however, this is beyond the energy levels produced by the six COIL modules used in the ATBL. A limited energy delivery rate also complicates the targeting problem. The longer the laser must dwell, the longer the target must be precisely tracked to maintain the rate of energy delivery. This is not just a problem of getting energy to the target missile, but to a small patch on the missile. Warming a large portion of the missile does not lead to the same rapid destructive effect as melting through a point on the target.

Nature also may impose a limit on how much energy may be delivered. Some laser energy is absorbed by the atmosphere as the beam makes its way toward the target. In fiction, a laser is portrayed as a visible beam reaching out from the weapon to the target. In reality, effects visible to any observer not directly along the axis of the beam are wasted energy. Dust and other airborne particles may scatter laser energy away from the target and in the process produce an eyesight hazard. Like the target, as well as the laser system itself, particles in the air, rain drops, and the gaseous air molecules themselves can absorb laser energy, heating up in the process. Besides reducing the power delivered to the target, atmospheric effects such as thermal blooming complicate the already difficult feat of keeping a beam focused on a moving point at ranges measured in hundreds of kilometers. Air at different temperatures has different optical properties, such as can be seen in the shimmering above a hot surface. The higher the energy is, the worse the effects are. Essentially the passage of high energies through the atmosphere provides a source of atmospheric distortions that inhibit the passage of high energy through the atmosphere.

The ABL program is known to combat the problems of high-energy delivery within the atmosphere in two ways. First the iodine lasing medium of the COIL system produces light at a wavelength (1.315 microns) that minimized absorption by the atmosphere.¹³ To counteract natural and remaining self-generating atmospheric distortions, a system of adaptive optics predistorts the beam so that the attack laser arrives focused at the target. Among the components of this active compensation system is a low-power laser sensor that measures the amount of distortion present. High-speed computer analysis of the external distortions generates commands to predistort the beam via mechanisms in the optics train before the beam leaves the aircraft.

Though not directly part of the ABL program, the advance tactical laser (ATL) also uses COIL technology—this time a small installation onboard a C-130 Hercules transport aircraft. This system is only meant to generate hundreds of kilowatts of laser energy, and has a range measured in dozens of kilometers. Unlike the ABL/ATBL, the ATL program is meant to study the use of a laser against ground-based targets; the Special Forces community is interested in its potential. According to the December 2007 Defense Science Task Force on Directed Energy Weapons, ATL is at an earlier stage of development than antiballistic missile defense oriented ABL work.

Using a different combination of chemicals are the ground-based THEL and related mobile THEL (MTHEL) programs. Although THEL is a lower-power system, with a shorter range, and ground basing that is technically less demanding, it has been able to destroy a wider variety of threats, including thick-skinned mortar shells. Israeli participation in the THEL program is related to the ongoing threat from short-range rockets, artillery, and mortars employed by terrorists. Low-tech rockets, artillery, and mortars, labeled RAM, and are an increasing threat due to their low cost, portability, and easy concealment in urban environments. Once fired, RAM threats provide little time for evacuation or defensive actions, often leaving retaliation and, more controversially, preemptive attacks in neighboring territory as the only options. The very low per-shot cost of RAM threats presents very serious economic problems to defense, where million-dollar interceptor missiles are used to counter rockets priced only at hundreds of dollars. Claims both for and against¹⁴ an operational THEL put the per-shot cost for the chemicals required at thousands of dollars.

Like ABL, the THEL program generated some discussion on a deployable version, including the MTHEL. Also like the ABL program, THEL fell behind schedule, again due to the many technical challenges associated with attempting to weaponize laser technology as a kill mechanism. THEL successes include destruction of in-flight short-range rockets, mortars, and artillery shells fired in salvo.¹⁵ The THEL program was shelved in 2005, a move decried by some politicians in Israel as the RAM threat still exists. On the other hand the cancellation revealed several troubling problems with the THEL concept at that point in time.

One inescapable issue with gas dynamic lasers is that their “fuels” tend to be bulky and often hazardous as well. Environmental concerns may limit the selection of prospective reactants, contributing to factors that have stalled enthusiasm for operational use.¹⁶ In turn, many current chemical laser programs and concepts counter such concerns with the option of an exhaust scrubber, and containment of exhaust in a sealed system.¹⁷ The amount of chemicals needed to operate these gas dynamic laser-based weapons also adds to the bulk, leading to deployment and vulnerability concerns. Earlier more ambitious laser-research plans of the United States included on-site and inflight reprocessing of laser reactants, allowing for potentially limitless magazines, as long as power and time were available.¹⁸ A regeneration system for recovering the chemicals needed for the laser would add, however, to the bulk and complexity of what is already a difficult-to-put-together system of systems.

The reagents used in the COIL are gaseous chlorine, molecular iodine, and an aqueous mixture of hydrogen peroxide and potassium hydroxide.¹⁹ Although these chemicals do seem relatively commonplace, with forms of each being found in bathroom medicine cabinets and in cleaning supplies, in the concentrations and purity needed for COIL some are quite dangerous. Chlorine gas has a reputation as a poison used in chemical warfare, and even lower concentrations used in water purification require protective equipment. Competing chemical mixes fare no better. The deuterium fluoride (DF) gas dynamic laser that THEL is based on is fuelled by precursor chemicals that are described as toxic.²⁰ Though exotic sounding, deuterium is simply a stable isotope of hydrogen, and can be extracted from natural water sources. The reactants that supply the fluorine on the other hand are described as both toxic and corrosive.

It must be remembered that laser technology is competing with physical-interception methods, such as interceptor missiles. Moore's law implies that the foundation technology for the sensors and guidance, electronics, becomes more powerful exponentially.²¹ Guided missile technology is a familiar technology, and despite many initial problems, especially with reliability, has matured over the years and the basic technology is generally trusted today. An example of this competition is the Israeli Iron Dome counter-RAM interceptor missile system—a system procured after the end of the THEL program. Though missiles do cost more on a per-shot basis, there are not quite as many risks associated with producing an operational system. Iron Dome was fielded in 2011 and has already claimed some operational success during rocket attacks in early 2012.²²

Chemically powered lasers, having demonstrated the ability to reliably generate HEL outputs, continue to prove useful in the development of ancillary systems, such as the optics train needed to accurately direct the beam. This is the purpose now of the YAL-1 ABL research on the technologies needed to field an HEL weapon. However, experience gained from chemically powered laser work has highlighted several problems that make operational deployment of this specific method of beam generation unlikely.

Lasers Part III: Electric Lasers and the Promise of Limitless Defense

Since the prominent ABL and THEL/MTEL gas dynamic chemical laser programs were curtailed, U.S. laser research has continued with emphasis on weaponizing electrically powered laser technologies. An electrically powered laser avoids many of the logistical problems of supporting a chemically powered laser, not the least of which is lacking the need to supply large quantities of exotic and potentially hazardous chemicals. The lack of an additional vulnerable logistical trail is just one factor in the perceived robustness inherent to many electrically powered laser concepts.

Although the science backs up the potential for many gain mediums to produce megawatt power laser outputs, engineering challenges have so far kept power levels at kilowatt levels. One immediate problem is dealing with the power levels involved, and the generated waste heat. Inefficiencies in conversion of energy, electricity to light, result in the generation of waste heat. In 2010, companies were making bold claims of better than 30 percent efficiency,²³ meaning the destructive energy delivered by such a laser would be only around a third of the energy handled within the laser system itself. Now of course these energies would not be concentrated on a tiny point inside the laser, but a slow cook can be just as destructive as the weaponized effects on the target. As many of these current laser proposals are for close-in weapons systems (CIWS), the final line of defense against salvos of guided missile and lately against multiple inbound RAM threats, the lasing material may not have much time to cool down between shots. It is not surprising that among the technologies promising to be the key to a working defensive laser weapon are high-temperature ceramics.

Although benefiting from the lack of a physical lasing medium that may melt or boil away, the FEL must contend with being able to generate a high-energy electron beam capable of in turn generating an HEL output. At the time of writing, the U.S. Navy announced a major breakthrough in this area, leading toward megawatt power levels down the road for its FEL program.²⁴ Though the existing 14-kilowatt prototype does not have the power needed for a weapon, the navy's demonstration of high power level electron beam technology is notable in the troubled history of laser weaponization for being ahead of schedule.²⁵ Despite this hopeful news, it must also be remembered that even optimists estimate that at-sea testing for a 100-kilowatt system would be feasible around the year 2020,²⁶ and this is contingent on funding. It would still be some time after this initial at-sea demonstration that the megawatt system hinted in the press release could become feasible. Again, the problem is dealing with the input energy requirements needed to function.

Lately, about the only part of the energy problem for electrical lasers where a solution is readily available is power generation, though with caveats. Naval DEW mounts would only be additional items on the list of electricity-hungry applications, such as advance radars, instead of a special requirement for power generation. If a warship is able to generate onboard the electrical power needed to power a DEW then a fixed ground installation would be easily conceivable. Generating and storing the power needed for an airborne electrically powered laser is another area of concern; however, the gas turbines powering many of today's warships often trace their lineage back to commercial airliner power plants. Smaller mobile power sources are, however, still a problem; however, the interest in “green” technologies such as, again, electric transmission, but this time for cars and trucks, is presenting a range of energy options for vehicle-mounted direct energy weapons. An electrically powered SBL would certainly benefit from advances in “green” power, such as increased efficiency solar panels and lightweight power storage.

The low power levels achieved thus far by electrical laser technology has not stopped these technologies from reaching the battlefield. Highlighting recent progress on electrically powered solid state lasers is the battlefield deployment of ZEUS-HLONS (High-Mobility Multipurpose Wheeled Vehicle [HMMWV] laser ordnance neutralization system), a relatively off-the-shelf industrial laser mounted on an HMMWV light vehicle. ZEUS-HLONS is meant to burn through and ignite IEDs and land mines for a slow burn as opposed to setting off a detonation. Explosives used by militaries and industry generally only detonate under specific circumstances, often burning before they would detonate. Standoff range is useful to such roles as not all bombs are composed of such safe explosives, and an ignition may still result in a lower-order detonation. This program has seen use in Afghanistan and Iraq, two conflict zones where IEDs are a severe threat to U.S. and allied forces. Unlike in-flight rocket, artillery shell, and mortar threats, taking minutes to burn off IEDs and unexploded ordnance represents a viable strategy and improvement over the time needed for manual ordnance disposal. This and other concepts for using off-the-shelf lasers for niche applications are useful in building acceptance of lasers on the battlefield after so many years of confinement to laboratories and being laughed off as fiction.

The kilowatt-class laser being used as a bomb disposal tool also represents how the concept of the laser as a weapon has evolved with the threats of the day. In the 1980s, the Cold War was the preeminent security concern for the United States; HEL technology was shortlisted in the SDI program as a possible defense against Soviet ICBM attack. In the 1990s, the tactical ballistic missile threat posed by rogue states, such as Iraq under Saddam Hussein, drove HEL development. The ABL program originally started off in this period with the aim of countering the more localized threat posed by tactical ballistic missiles. Since 2001 and the start of the Global War on Terror, a major role being promoted for HEL development is in countering asymmetrical threats posed by subnational entities, such as IEDs and unguided RAM threats.

Although HEL weapons may be used offensively, they have over the decades been promoted mostly for defensive roles, and specifically for providing a shield against inbound munitions. Part of this is of course avoiding negative perceptions associated with developing what is basically an entirely new and untried kill mechanism. This is not just avoidance of criticism from pacifist communities, but also from existing weapons communities whose budgets and projects may be threatened by this futuristic technology. Of the recent U.S. DEW programs, only the airborne tactical laser is openly being promoted as only a research program to investigate the utility of a destructive laser weapon in support of forces on the ground,²⁷ offering both precision and novel effects to set it apart from existing capabilities.

Defensive weapons, specifically weapons that attack munitions mid-attack, on the other hand represent a relatively new capability. Existing antimissile capabilities are often likened to “hitting a bullet with a bullet,” in past a charge by critics to indicate futility at the effort, but now more of a boast from counter-missile system supporters as the concept has at least been made viable by modern computer technology. In this sense, lasers and other DEW-based antimissile systems would seem to be redundant; however, the same technology that has allowed missile defense interceptor missiles to be successful is also applicable to threat missiles. Also, new categories of threat have emerged from technology proliferation. Instead of attack by a single highly capable missile, low-cost electronics allow the construction of swarms of low cost, but still capable, munitions to overwhelm a defender. The asymmetrical threat environment now emerging presents several challenges that can be met by DEWs due to their potential for speed of attack, and potential for “limitless magazines.”

EM radiation propagates at the speed of light, 299,792,458 meters per second,²⁸ meaning an EM-energy-based weapon will hit its target for all practical purposes instantaneously. In the face of both stealthier and faster (supersonic and hypersonic) missile threats, there is a fear that physical missile interceptors will not have the capacity to maneuver to successfully intercept in the shrinking time window between detection and impact. Vertical launch systems have become something of a norm for interceptor missiles, in part due to their capacity to rapidly launch against multiple targets compared to reloadable missile launchers, the missiles being responsible for actually pointing itself toward the target once clearing the launch tube. The aforementioned Iron Dome system uses a deployable battery of vertical launch tubes. Vertical launch works in part because the interceptor has time and propulsion capacity to rapidly point itself toward the target before actually accelerating toward the target. This flight path from launcher to target involves a rather dramatic turn: the greater the rate at which a missile has to change direction, the greater the G-force involved. Future threats may not present enough time for such a maneuver, or physical technology may not be robust enough to conduct the necessary form of maneuver.

For a DEW-based defense to be competitive, it must be capable of rapidly and reliably producing a destructive effect. One DEW “turret” can only attack a salvo threat one target at a time, whereas many missile systems can conduct multiple simultaneous interceptions. Although this comparison seems to be to the detriment of DEW, the impression breaks down in the details: the number of multiple simultaneous intercepts is limited by the missile system's capacity to have multiple interceptors in flight at any one time. Fire-and-forget technologies do mitigate the fire-control burden, but increase the cost of the interceptors. Also, the time it takes for an interceptor missile to conduct an attack, and the time for a miss to be recognized, may not leave enough time for another interception to be attempted. Generally multiple interceptors would be launched simultaneously against one target to increase the probability of an intercept; this, however, has consequences again on the number of targets that can be attacked. If a DEW-based defense can destroy more targets during the flight time of a missile-based system attacking its theoretical maximum number of simultaneous targets, then the DEW-based system is superior in the rate of interception due to not needing multiple interceptors. Therefore, scaling up the power of the laser to where it can outperform legacy technologies becomes the primary technological barrier, as without a significant increase to how fast individual threats are destroyed, a DEW would be no better than physical interception systems.

One limitation that the missile battery and the chemical-powered lasers of the THEL and ABL programs share is that they only have a finite number of shots. The electrically powered laser on the other hand will fire as long as power is supplied to it, and as long as it remains intact. Electrical power is reasonably plentiful, but much research and development is needed to first generate a worthwhile laser output, and then having that laser operate reliably. Once these technological challenges are overcome, then an electrically powered laser weapon would have a practically unlimited magazine. A “limitless magazine,” plus a faster engagement rate, may not equate to an impenetrable shield, but it may be necessary to keep up with saturation threats.

As mentioned earlier, one potential metric of the effectiveness of a defense is the per-shot cost relative to the cost per shot of the attack (this measure, however, is often ignored due to the overriding value of the asset being protected); intuitively, an electrically powered laser defense could excel in per-shot cost effectiveness. Ignoring for the moment the cost of what is still expected to be a long research and development period, we could say that electrical power is plentiful in many situations right now and is expected to only become more plentiful due to other demands for generating capacity. Keeping a laser- or other DEW-based defense operating would be a matter of burning more fuel to run the generators.²⁹ Logistically, this would give an electrically powered direct energy weapon an advantage as necessary fuel and ammunition are one in the same.

Although the chemically powered laser is a technology that is much nearer to being a fielded capability in that it has demonstrated the power levels close to that needed for a weapon, it is not the form of laser technology that offers the full promise generally advocated by DEW supporters. Aside from the many problems experienced by the specific ABL and THEL programs, these two systems could also be considered interim capabilities, potentially starving funding from both the R&D needed to mature higher-payoff electrically powered systems and from refined methods of physical attack that are still effective in the short term. This also highlights again that the timeline for a deployed destructive laser weapon, outside of a few niche applications such as bomb disposal, will still likely be years, if not decades.

Indiscriminate Energy Weapons

In a way energy weapons have been available since World War II through the EM effects of a nuclear detonation. Depending on where the detonation takes place relative to the surface of the earth, different mechanisms for damage will be enhanced. A surface or underground detonation, expends some of the device's energy against the ground, limiting blast effects. A correctly situated airburst will magnify the blast effects as the shock wave of the explosion is reflected back on itself by the ground (this works for conventional explosives as well). At a high-enough altitude, the energy released by a nuclear detonation with interact with molecules in the upper layers of the earth's atmosphere, as well as the earth's magnetic field, to produce wide-ranging EM effects. Basically this final configuration for detonation turns the nuclear weapon into an indiscriminate energy weapon.

High-altitude nuclear events or explosions (HANEs), also known as high-altitude nuclear detonations (HANDs), have many destructive effects on computers and electronics. A portion of the energy released from a nuclear detonation is in the form of high-energy particles. These high-energy particles can get caught in the earth's magnetic field, just as natural high-energy particles do. In both cases these temporarily trapped particles form radiation belts, the Van Allen belts being the natural ones. When there is an overflow of particles, beyond enlarging and enhancing the natural Van Allen belts, extra radiation belts form in regions that usually do not have them. For satellites not designed for prolonged operation in the natural-radiation belts, repeated exposure to these unexpected zones of highly energetic particles will drastically cut down on component life and lead to very early satellite failure.³⁰ These artificial belts naturally lose particles over time, as they are not continuously replenished by sources such as the sun, but can take years to dissipate.

On earth, the energy released by the HANE will setup various line-of-sight and non-line-of-sight EM effects. This includes high-energy particles bombarding the sparse molecules of the upper atmosphere, the energy of which is then reradiated as EM energy. The EM energy unleashed by a nuclear detonation interacting with the earth's magnetic field results in geomagnetic effects. The high-energy EM pulse (EMP) of the detonation itself, and reradiated EM effects in the radio-frequency (RF) portion of the spectrum, can interact with electronics and electrical equipment, setting up unwanted signals and electrical currents that may burn out both large circuit breakers and the microscopic logic gates of modern electronics. Electrical infrastructure is vulnerable from the long transmission wires; EM interactions will setup currents and high voltages that may destroy critical electrical transformers. Scenarios have been given where a single, moderately sized, nuclear detonation is able to wipe out the electrical infrastructure of the entire continental United States.³¹

The damaging effects of a HANE are not theoretical. Solar weather can also result in similar effects as a HANE, including overwhelming the natural outflow of particles in Van Allen belts, which result in satellite damage. Severe solar activity can make the northern and southern lights visible at lower latitudes. The EM effects of natural solar activity has on occasion knocked out entire power grids, as it occurred in the province of Quebec, in Canada, during particularly active solar activity in 1989. These natural events both add to the knowledge base concerning EM weapons and serve as additional incentives to harden infrastructure—EM warfare is not a certainty, but severe solar weather, like earthquakes, are only a matter of time.

For the United States the most well-known demonstration of the damage a HANE could generate was by accident in the consequences of the 1962 Starfish Prime nuclear tests. The tests had a nuclear detonation of around 1.4 megaton yield, at a mere 400 kilometers altitude. This detonation had several unexpected results, including the generation of extra radiation belts that damaged several satellites over time and a larger-than-predicted EMP. This EMP is credited with knocking out traffic lights and causing other EM interference in Hawaii (roughly 1,500 kilometers away from the Johnson Island test site).

It must be remembered that the power, telecommunications, and other electronics that were disrupted and in some cases damaged, were from the 1960s and are generally regarded as being somewhat more robust than today's computer devices. Modern computer circuits are minuscule in comparison, and operate on a fraction of the power. Static electricity from a careless technician is enough to destroy a modern computer chip. Also, it must be remembered that in the 1960s practically no aspect of day-to-day life was reliant on computers, whereas today a strong argument is made that Western civilization is computer dependent. Indeed, the United States of the 1960s was not quite as dependent on electricity as it is today. Therefore, although nuclear weapons and delivery technology has become more potent, Western society has become more vulnerable outside of expensively shielded and hardened military equipment.

Although none of these effects, except perhaps the blinding light of a nuclear detonation, are directly harmful to people, a wide-area EMP attack perpetrated against the United States would in the long term lead to significant loss of life. The disruption to medical services due to loss of power, communication, and potentially direct failure of life-support equipment, would be an indirect casualty mechanism causing significant loss of life within minutes to days. The loss of power to utilities would lead to water shortages in many locations, leading to further casualties over a period of days and weeks. Disruption to food production and transportation could eventually lead to mass starvation in only a few months. The disruption to fuel supply and transportation would also leave many trapped in the dead cities of this worst-case scenario. Globally there would be economic repercussions as the largest economy is suddenly removed from the grid. Simultaneous and permanent failure to many critical elements of the North American power grid could take years to repair and would be a cripplingly expensive recovery.

A HANE attack would of course have military repercussions. In orbit, satellites would begin to fail, including many critical to the military space-force enhancement, limiting options for a conventional response. This would be true if the detonation was situated to avoid damaging terrestrial infrastructure. The loss of a conventional military option, at least one supported by space systems as has been the preference since the 1991 Gulf War, raises the problem of what to do next. The HANE attack being perpetrated by another nuclear power gets mixed in with nuclear deterrence and the controversy over whether a limited nuclear attack between nuclear-armed powers was possible without escalation. According to the 2004 Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, post-Cold War Russia and China have considered the idea of using the EMP effects from a limited nuclear strike to “paralyze” the United States.³²

The U.S. nuclear forces are meant to be hardened against the effects of a general nuclear war, and despite the end of the Cold War, and the de-emphasis of the nuclear mission by both the Bush³³ and Obama administrations, the United States still maintains all three elements of the nuclear triad of bombers, ICBMs, and a fleet of ballistic missile submarines. Tactical nuclear war, or the limited use of nuclear weapons, is problematic, in that it may escalate to all-out nuclear war. All-out nuclear war leads to the still-applicable Cold War concept of mutually assured destruction (MAD), wherein enough retaliatory forces exist such that one power could not ensure the loss of the other's ability to deliver a crippling retaliatory attack.

Proliferation, however, has meant that the technology needed for a HANE attack has spread to others who may not fit into the model of nuclear-armed great powers deterring each other with reasonable effectiveness. The concept of rogue states, nations led by leaders who regularly flaunt international norms, includes the possibility that nuclear deterrence may not work against these regimes. Indeed there are fears that proliferation may eventually deliver nuclear weapons into the hands of terrorists, subnational entities that exist outside of the international system of nation states. Put simply, nuclear deterrence would not work against terrorists in that they would not have anything worth using a nuclear attack to retaliate against.

One possible scenario is the nuclear anti-satellite (ASAT) employed by a newly armed nuclear state, wherein a HAND would not be able to disrupt life directly in the United States, but instead destroy the satellite infrastructure needed to intervene militarily in a regional conflict. This scenario is applicable to an emerging nuclear-armed nation, one that does not have the ability to threaten the United States itself, but simply wishes to prevent the United States from acting in its vicinity. The loss of military space-force-enhancement assets would hamstring conventional forces. If the disruption was great enough, the only way to proceed with conventional warfare would be to accept high casualties and collateral damage. Nuclear retaliation would bring its own moral and ethical problems. A newly armed rogue nuclear state would have few, if any, nuclear weapons remaining after its nuclear ASAT bid to prevent U.S. intervention. Moreover, it has limited its use of nuclear weapons to only prevent the deployment of global U.S. power. Would the loss of critical, but largely unmanned, infrastructure to intervene in a foreign conflict warrant a nuclear response? Related to this would be the loss of commercial and other nonmilitary space infrastructure, much of it necessary for the modern world to exist. Would destroying a foundation of the Western way of life, but again without massive direct loss of life or an immediate threat to the homeland, warrant nuclear retaliation? Is proportional response sacrosanct, or would this warrant a nuclear strike to deter future rogue states? This troubling scenario the author has in previous works referred to as a possible way to “effectively get away with using a tactical nuclear weapon,”³⁴ or in other terms, the nuclear ASAT is the tactical nuclear weapon of the information age.

High-Power Microwave (HPM) and Radio Frequency

The preferred method of warfare in the West, and the United States in particular, is one of precision. Aside from the laser, there is interest in direct energy weapons that attack electronics through RF, but not of the indiscriminate nature presented by a HANE. Some of this is in dedicated programs to build RF weapons, similar to the concept of the radio “death ray” noted at the beginning of this chapter. Other capabilities are falling out of the high transmission power levels inherent in many radar-sensor suites. In light of the fact that some early radar research had roots in trying to create a DEW, it is somewhat ironic that radar sensing, RF jamming, and finally RF attack are converging in some multipurpose radar arrays being marketed today.

Historically, radar and radio transmitters have been known to unintentionally disrupt aircraft systems. Shades of this are seen on every commercial flight as the cabin crew warn passengers to turn off mobile telephones and other electronics. All aircraft are shielded to some degree from EM interference (EMI); however, in operational use, shielding may become damaged, or may encounter a signal source it was not meant to protect from. Conversely emission standards for electronic equipment are meant to prevent internal generation of damaging signals; however, again devices may on their own malfunction in this regard. Among the many difficulties and costs of systems integration are getting fully functional electronic devices to work together inside cramped avionics and electronics bays. Finally, there are existing electronic warfare (EW) systems, some of which can radiate enough energy to damage radar components.³⁵

Radar, radar warning, and communications antenna are naturally vulnerable points with respect to EMI as these are intentional and necessary openings for EM energy to pass through. Radar and communication jamming simply overwhelm a particular system with RF noise, degrading its ability to receive anything intelligible. For electrical engineers on military projects, the problem is how to have these openings without compromising the EMI resistance overall. Again, all this contributes to the high cost of weapons platforms today. Shielding itself can be overcome with enough energy.

The world of EW has, since its beginnings, been shrouded in secrecy. For many, EW is an arcane and unseen battle between black boxes. Although the results are quite important, they are generally invisible, adding an additional layer of obscurity. On the other hand, the use of RF and microwaves in a destructive mechanism against more than signal reception has been investigated since at least the 1930s, with no tangible results, leading to a degree of skepticism over this line of research leading anywhere. A laser weapon is something the general public and policy makers at least have some concept of from fiction. EW is both intentionally hidden away and unintentionally misunderstood by the public at large and possibly by many policy makers.

In the very near term, a single-shot EM weapon is feasible. Since the mid1990s, Australian defense analyst and electrical engineer Dr. Carlo Kopp has been discussing the potential to build such a weapon involving an explosively driven power system coupled to the proper transmitter.³⁶ Although not commonplace, there is nothing that is part of science fiction about converting a fraction of the mechanical energy released by high explosives into electrical energy. A high-explosive detonation has a timeline, by definition a burn rate higher than its speed of sound, which means plenty of time for this energy to be harnessed via electromechanical apparatus. Indeed there are a range of technologies, including the explosively pumped flux-compression generator, described by Dr. Kopp as a “mature technology” in the 1990s, and magnetohydrodynamics (MHD) technologies.³⁷ The latter has also been applied in less-destructive forms of electrical-power generations, having being used to extract additional electricity from waste heat in existing thermal power stations. Here again the technology may sound fictitious, but it already exists and is in use internationally.

Although perfectly fine for an EM warhead, the idea of using cartridges filled with explosives and electronics, like the chemical-supply reality of existing HEL demonstrators, does not fulfill the “limitless magazine” promise of DEWs. Again, for many installations the power supply of a warship is considered necessary for initial deployments of RF and HPM-beam weapons. Naval interest in RF and HPM is due to this type of EM energy's potential to cut through atmospheric conditions, such as fog, found during maritime operations. Indeed real and persistent criticism of laser technology is the ease at which it may be blocked by dust and other environmental factors, let alone intentional attempts at disrupting the conditions needed for beam propagation.

RF and HPM weapons are beginning to emerge into the public eye. In 2008, the U.S. air force tendered for equipment to test the feasibility of airborne HPMs that would be able to interfere with, and possibly destroy, targeted electronics.³⁸ This was all done in the public, as opposed to some very secret “black” program such as early stealth work. Aside from being a multishot system, and having a very modest budget of about $40 million,³⁹ the counter-electronics HPM advanced missile project (CHAMP) is aiming at being flown on an unmanned aerial vehicle (UAV). Boeing was awarded the contract in 2009, with a press release noting that this will be the first time an HPM weapon has been integrated with aircraft.⁴⁰

In perhaps another sign that RF and HPM may be about to emerge as a viable defense technology, Raytheon is marketing the Vigilant Eagle system for protecting airliners from the threat of man-portable air-defense (MAN-PAD) missile systems. Terrorists have already demonstrated both the ease at which MANPAD systems may be acquired, and an ability to bring them within range of civilian runways.⁴¹ Basically Vigilant Eagle is a ground-based system for rapidly detecting, and attacking with EM energy, portable and easily smuggled antiaircraft missiles. The EM energy projected by Vigilant Eagle is meant to interfere with the electronics of a MANPAD and other short-range air-defense (SHORAD) missile. Precision over the beam and its effects would be absolutely essential for this system to avoid itself becoming a risk to civil aviation.

These two examples of recent EM weapons work are short-range systems; CHAMP is UAV mounted to get it near targets without risking an aircrew, and Vigilant Eagle is meant to provide local defense against very short-range missiles. In general, RF and microwave beams do spread out more than lasers do, though not as much as incoherent light (in or near the visible portion of the spectrum). Radio waves and microwaves are on the larger end of the EM scale; therefore, these technologies have fundamental limits on how far they can be focused. That being said, RF and microwaves are largely immune to being blocked by atmospheric conditions (for instance radar can “see” through fog, while your eyes working on visible light cannot). Also RF and microwaves can penetrate through materials that are mostly opaque to other parts of the EM spectrum. Indeed that is the point of an RF or microwave weapon—to penetrate not just into a target, but into the electronics that make it a high-technology threat. Finally, being relatively shorter range compared to the theoretical focus limit of a laser (which in atmosphere systems still have far to go before reaching) is still a militarily useful distance at several hundreds of meters.⁴²

This emphasis on targeting the “black boxes” of a target does, however, raise the problem of battle-damage assessment. Unlike an HEL, which is meant to provide a visible effect of an exploding missile or shell, destroying the ability of electronics to function correctly does not leave much in the way of immediate signs. A successfully attacked computer system, to most conceivable methods of remote observation, looks identical to a computer system that is simply turned off. Part of EW is detecting that one has been attacked, which opens up the opportunity to simply “play possum” and turn off the attacked, but still working, system in anticipation of surprising the attacker. For a system such as Vigilant Eagle there is the additional problem that a successfully attacked missile may still impact the airliner being protected. Unless the electronic interference causes the threat missile to violently go off course or prematurely detonate there is no way to know if the threat was neutralized. Indeed, if the missile's electronics are simply burned out, the missile may still be flying toward the unaware airliner with a chance of hitting it.

The problem of battle-damage assessment is linked to the question of where electronic attack fits on the battlefield. Is it a means of support—to increase the odds for a traditional weapons’ platform to attack with traditional “kinetic”⁴³ munitions? Or are the energy levels involved in an RF and HPM weapon sufficient that these systems can be used directly as the only means of attack? In an era of tight budgets, the next natural question is how much can be spent investigating the promise of RF and HPM weapons? Which is of course countered by the question: what is the price for not increasing the budget to include RF and HPM weapons?

The other side of RF and HPM weapons research is the vulnerability of the U.S. military and Western society in general to such electronic attacks. A benchmark for today's hi-tech society is the sheer proliferation of computer chips and wireless networking; both elements are connected to an earlier foundation of modernity, the electrification of society. As mentioned earlier, both Russia and the People's Republic of China have in recent doctrines considered the option of using nuclear weapons to achieve the effect of shutting down modern life in the United States. For near peers, the smaller area of effect from EMP warheads based on nonnuclear technology would avoid many of the problems of the “limited nuclear war” concept. Also by being nonnuclear, such systems would face few barriers to open proliferation in the world's arms markets. Nonconventional-warfare technology, such as GPS jamming equipment, meant to nullify the bulk of U.S. guided weapons is available for sale, and has even seen combat use against the United States.⁴⁴

Less-than-Lethal Weapons and the Potential for DEW to Save Lives

On one end of DEW research is the problem of delivering sufficient energy to rapidly destroy, whereas on the other end the problem is delivering limited amounts of energy to achieve coercive effects but otherwise remaining harmless to the target. In general these systems face controversy not over feasibility, but over the potential for misuse. Directed energy, used in a less-than-lethal manner, is a new capability, with many unknowns as far as doctrine, capabilities, and risks are concerned. Limited understanding of these systems has led to many misconceptions about the technology.

The term “less-than-lethal” replaces an earlier term “non-lethal,” when describing the same thing. Although a seemingly more friendly term, “non-lethal” gave rise to the incorrect impression that systems under this label had no lethal potential. Used incorrectly, many less-than-lethal technologies do have the potential to cause loss of life—rubber bullets and batons (clubs) can and do kill. Less direct, but just as deadly, would be the case of mass panic triggered by the use of a less-than-lethal weapon. In such mass-panic incidents there would be great potential for trampling and asphyxiation as direct casualty mechanisms. Of course lethal weapons could also lead to the same circumstances, which brings up the question of whether a technology can be made culpable when assigning blame in the aftermath, and if blame is assignable whether it was more a problem with the doctrine, and those implementing it, rather than the equipment.

Lack of understanding over the capabilities and limitations of a tool contributes to it being used incorrectly. Amnesty International, in a 2008 report on the use of “stun weapons” in the United States affirmed the organization's support for the development of less-than-lethal weapons technologies, as encouraged by international standards,⁴⁵ but was very concerned over the potential for misuse, and the safety of such devices. Among the issues raised was that the use of “conducted energy devices” (CEDs), or more commonly “Tasers,” named after the most well-known brand, that have gone beyond being an alternative to lethal force, and had a lower threshold for deployment. It should be noted that the scope of the report was concerning the use of CEDs by law enforcement in the United States, a nation with significant oversight and limits on law enforcement, as well as other avenues for legal recourse for those who feel they have been wronged by the authorities.

Criticism that less-than-lethal weapons technology has a greater potential for “overuse” is related to the idea that less-than-lethal coercive force is perceived as having less “gravity” than lethal force. At the same time, the remote nature of many less-than-lethal technologies, a selling point for directed energy systems, does not equate this form of coercive force with close-in physical forms such as use of batons and truncheons.

To a degree, the “harmless” nature of less-than-lethal weapons technology in general has been oversold, resulting in a backlash when real-world results do not match the clean and bloodless claims. Although there has been criticism of CED employment, there is also the fact that these devices have been used quite frequently as an effective substitute for lethal force, saving lives in the process. Again, it should be stressed that less-than-lethal capabilities are a relatively new development for law enforcement. It is unfortunate, but doctrine and policy often spring from the aftermath of accidents and misuse. Not every real-world contingency can be foreseen. With all matters of coercive force, is it the tool itself or how it is used and who is using it that should be the primary subject of critical examination.

For some in the military the concept of less-than-lethal force is an alien concept, leading to difficult questions on the role of military force in operations other than war. As an instrument of foreign policy, the militaries of the United States and other Western nations, whether rightly or wrongly, are being employed in operations other than war. In the 21st century, civilian and military leaders have stressed the need to win “hearts and minds,” if they were to achieve long-term victory. The United States has as of late found itself embroiled in multiple military operations other than war, where there is a need for civilian crowd control, as well as regular situations where distinguishing threat from innocents is difficult. Without less-than-lethal options, lethal firepower is often the only recourse, leading to locally tragic outcomes, as well as contributing to hostilities that would be counterproductive to the overall mission. However, in a war zone over self-restraint could result in one's own death and overall could also lead potentially to defeat. Traditional military weapons are meant to be lethal; meaning the avoidance of lethal force often translates into standing by while possibly allowing an enemy to attack. Military less-than-lethal weapons are envisioned as a third option: to employ coercive force to neutralize a potential threat but without necessarily killing the potential threat.

In the face of all the technical and political opposition to less-than-lethal DEWs, capabilities are slowly making their way into operational service. Though it was not used operationally, the U.S. Active Denial System (ADS) did make its way, briefly, into the war zone of Afghanistan in 2010.⁴⁶ ADS operates on the millimeter wave part of the EM spectrum, more associated with relatively safe radar and RF communications than the microwave-based cooking appliance found in most U.S. kitchens. Active millimeter wave technology is also used in some airport security scanners,⁴⁷ meaning U.S. frequent flyers may see more exposure to this part of the EM spectrum than anyone targeted by ADS in a warzone.

The broadcasts made by ADS are meant to penetrate less than half a millimeter into human skin, officially given as “1/64th of an inch”⁴⁸ to produce an “intolerable heating sensation.”⁴⁹ This effect is meant to cause targeted individuals, or groups, to remove themselves from the beam. ADS avoids applying physical force or contact on the target, setting it apart from other less-than-lethal technologies, including water cannons.

ADS has faced controversy on many fronts. On one side there are those who have been arguing for immediate deployment since the moment ADS hardware was available. Often support for an accelerated ADS program is made alongside claims that it could have prevented some of the collateral loss of civilian life during U.S. operations at the time in Iraq and Afghanistan.⁵⁰ On the other side are those who oppose it due to its potential as an instrument of torture. An “intolerable heating sensation” combined with no avenue for escape could be construed as a form of torture in some opinions, including in cases where the lack of escape was purely accidental.

Proliferation could lead to this technology falling into the hands of regimes that would have less concern over causing pain and suffering, accidental or otherwise. The ability to cause discomfort, and possibly pain, without physiological effect is troubling as it is potentially torture without evidence. During the writing of this chapter, several popular uprisings in favor of democratic reform were occurring across North Africa and the Middle East, and less-advanced forms of crowd-control technology were employed by the regimes then in power with varying levels of success. During these confrontations there were many fatalities. Although it is uncertain if relatively benign forms of crowd control, such as ADS, are of interest to undemocratic regimes, they already have access to existing crowd-control technologies and do not seem quite as concerned over the injury potential of what they have on hand; the availability of such technology to them would be somewhat troubling to general U.S. and Western policy in support of democracy globally.

The particular application of millimeter wave energy employed by ADS is very new, meaning there is worry about its effects. ADS operates at 95

GHz,⁵¹ which does technically mean it is operating in the broad range of the spectrum classified as microwaves,⁵² which range from 1 to 300 GHz. Specifically, it fits into the International Telecommunication Union (ITU) classification for extremely high frequency (EHF), which is also a band commonly used for satellite communication, as well as WiMAX Internet access. NATO's system for RF classification would put ADS in the M-band, whereas the IEEE would call it a W-band system. EHF is also two bands higher than UHF radio and TV broadcasts of the past. Microwave ovens operate at less than 5 GHz, and in some cases at wavelengths technically below the microwave portion of the spectrum. Unfortunately these fine details have not prevented ADS from being confused with cooking technology.

Although all of the wavelengths involved are nonionizing forms of radiation, the photons involved do not have enough energy to knock electrons from atoms (thus making them very chemically reactive), there are persistent claims made about the damaging effects of RF communications (cell phones, wireless networking, radio) in the face of science consistently disproving such claims. On the EM spectrum, ionizing radiation, such as UV that is linked to cancers of the skin, is on the other side of the visible light from micro and radio waves. For that matter, heat (infrared radiation) is between microwaves and visible light.

Now it is true that ADS is not entirely harmless, it does officially have a “1/10 of 1% chance of injury.”⁵³ Of the hundreds of test subjects who have been exposed to ADS, a handful have sustained minor burns, usually not requiring medical attention. So far the worse injury has been described as blistering.⁵⁴ One case of blistering requiring some medical treatment, and occurred due to accidental overexposure⁵⁵ out of what is still prototype software and hardware. In context, other less-than-lethal coercive technologies are also far from harmless, with consequences of exposure that include permanent maiming and death. Also, an effective less-than-lethal weapon does not include a requirement for complete lack of harm. However, despite the potential of this system, it has thus far been limited to being used on volunteers from the military, as well as members of the media, and those associated with the defense industry. It is of note that the military ADS program may not be the first operational use of this technology—contractor Raytheon is offering a scaled-down version to law enforcement and other domestic agencies for crowd control and infrastructure protection applications.⁵⁶

Prior to ADS, there was great interest in using sound waves as a form of crowd control. Sound waves, as noted in the beginning of this chapter, are a form of energy. Technology such as long-range acoustic device (LRAD) by the LRAD Corporation is able to project sound in a very narrow cone to comparatively long distances, for a sound system. It is marketed as a communications device with an impressive ability to deliver a message to a specific target. LRAD technology, like any powerful speaker system, is capable of causing discomfort. Recently it has been employed by shipping to drive off pirates attacking shipping near Somalia.

Beyond simply projecting a very loud and uncomfortable noise, there has been long-term interest in using infrasonic sound, sound waves below that which humans can hear, to cause discomfort, disorientation and other coercive physiological effects.⁵⁷ So far much of this research has been inconclusive.⁵⁸ Another factor to consider is that the degree to which sound produces a physiological response differs for individuals. An effective weapon is one that produces reliable results, such as an “intolerable heating sensation.” There are devices that produce a frequency of sound audible by a large percentage of teenagers, but inaudible to adults due to physiological changes with age. These systems are marketed to retailers in a bid to prevent teens from loitering around store fronts where it might be available, though these have come under some criticism due to their indiscriminate targeting of youth regardless of their behavior.⁵⁹

As a less-than-lethal DEW, optical dazzlers have seen much more operational use. These types of systems include low-power lasers used both to get people's attention, in the context of warning them to slow down for a checkpoint, and to induce temporary vision impairment in tactical situations. For intentional tactical uses, laser dazzlers are useful in that they avoid accidental exposure due to their high degree of directionality—only someone on the axis of a laser beam will be affected by it.

Now wording is important on this subject, as there are treaty obligations restricting the capability of military dazzler lasers. The United States, as a party to the 1980 Convention on Certain Conventional Weapons (CCW), is obligated to avoid weapons that are specifically intended to cause permanent visual impairment.⁶⁰ Specifically it is Protocol IV, Protocol on Blinding Laser Weapons of the CCW that limits the United States and other signatories from laser devices used in warfare, which are specifically used for permanent blinding. Essentially this means that between optical dazzlers and HELs there is wide range of energy levels and exposure mechanics that must be avoided as long as the treaty remains in force for the United States. Operationally this manifests itself in a combination of intentionally low power levels, electronic safeties (including systems to judge how much power is being delivered and systems for recognizing human eyes being in the line of sight), and training of operators.

This protocol does not restrict the use of weapons that may cause permanent blinding as a collateral or accidental effect, only systems where the desired effect is permanent blinding of human eyesight. Laser devices may still be used to damage optical-sensor equipment, opening potential loopholes for using optical-jamming equipment, which are not covered, as these devices are not specifically antipersonnel in nature. The proliferation of optical and heat-seeking missile threats has led to calls for civilian airliners to be equipped with countermeasures, including laser-based jamming systems that destroy a missiles ability to “see” the airliner. This means that potentially civilian airliners would be equipped with these devices, with potential for causing eye damage to those on the ground if they ever had to be used.

HEL weapons may, as a side effect, cause optical discomfort and injury from many of the atmospheric effects that inhibit propagation of laser energy to the target. Energy not delivered to the target has to go somewhere, and may be scattered in an unwanted manner. Air molecules may also absorb sufficient laser energy to briefly become incandescent. HEL weapons are not alone in their potential to cause collateral eye damage—some chemical reactions that may have potential as explosives generate damaging amounts of light, as do nuclear detonations. Again, these are collateral effects and therefore not covered by the CCW.

It is alleged that being a signatory to the CCW has not stopped other nations from procuring antipersonnel laser weapons capable of causing permanent blinding. Norinco, a Chinese company with a large portfolio of products, including many military goods, was for a brief time in the late 1990s marketing the ZM-87 Portable Laser Disturber,⁶¹ a system some sources have cited as being sold with blinding as one of its antipersonnel capabilities, in addition to the less-controversial counter-optical sensor and temporary dazzling functions. In one article concerning laser illumination of U.S. helicopters by North Korean forces, the ZM-87, as one possible laser system possessed by the North Korea, is described as being capable of causing eye damage under some circumstances.⁶²

Another aspect of using lasers to temporarily confuse sensors and human eyesight is the problem of accidental exposure. The proliferation of lasers has, however, led to a rapidly growing database on unintentional, nuisance, and malicious laser exposures. Every year there are hundreds of these incidents reported. This has included the illumination of commercial aircraft, with the result of impairment to the vision of the pilots.⁶³ It should also be stressed that these aircraft are at low altitude carrying out takeoffs and approaches for landing, meaning not only are these laser illuminations interfering with the safe operation of aircraft, they are doing so while aircraft have the greatest potential to hit the ground. Sometimes the laser illumination was found to be accidental, such as from light shows. At other times individuals have been prosecuted for illegal use of laser devices. Lasers able to project intense beams over long distances, such as relatively new battery-powered green light lasers, are freely available for under $100 in the United States, adding to concerns that the military may be far behind the general public in using lasers to interfere with vehicle operators.

Related to the use of lasers as a means to temporarily or permanently degrade human eyesight is the use of lasers as an ASAT weapon. The sensors aboard optical reconnaissance satellites are like the optical sensors on a missile, susceptible to temporary and permanent damage from exposure to relatively low-power laser illumination. During the Bill Clinton presidency a U.S. laser was used to illuminate a U.S. satellite as part of tests to assess satellite vulnerability, and sparked fears over U.S. intentions to deploy a laser ASAT capability.⁶⁴ Recently the Chinese have been accused of using a satellite-blinding capability against U.S. satellites, but like the previous example this may have just been another laser sensor test though one has to wonder why China chose to illuminate a foreign satellite if the test was intended to be of a benign nature.⁶⁵

The CCW also does not prohibit the use of lasers with an intended lethal antipersonnel role. If the hundreds of kilowatts of laser energy delivered by ATL are capable of antimaterial effects, then surely it should be enough energy delivered to have some kind of lethal antipersonnel effect. In the antipersonnel role, a laser would have the potential advantages of range over other precision antipersonnel methods such as sniper rifles, which have to contend with gravity, air and wind resistance, and are limited in the end by ballistic technology. Being a new technology, there is also a potential for “novel” effects against a human target. At the same time, some of these novel effects could lead to criticism as opponents of such technology could make a claim that these effects would constitute a breach of international standards and norms. More than one article has indicated that there is a reluctance to discuss the potential lethal antipersonnel uses of DEW, despite there being no actual inhibitions (norms and treaty obligations) against it.⁶⁶ Like the counter-missile role, the speed of lethal effect would be important to determining whether a laser system would meet obligations on the avoidance of excessive injury.

Ironically, the use of DEW as simply a longer-range precision target engagement capability has the potential to save lives under the same rationale that defines the legitimate military role of snipers. In a way, DEW is the ultimate application of the precision-warfare paradigm, the ability to not just reliably bring specific pieces to equipment under attack from a standoff range, but the ability to target specific components, and troubling individuals. This last class of targets, specific individuals of concern, people who are enemy leadership and facilitators, such as terrorist bomb makers and financiers, takes DEW research into the controversial topic of targeted killing. This is a grey area in international behavior, and touches on the fluid delimitation between legitimate military activity and espionage. Some specific individuals are clearly military targets, such as uniformed commanders in times of war. However, others are not so clear; although a bomb maker killed in the act of constructing an IED would be the legitimate elimination of a clear and present threat, the terrorist financier is for many less of one.

A large-enough engagement range would allow a U.S. DEW platform to be hovering in international airspace, while the target may be residing well within an uncooperative nation. This is an operational concept that raises its own complications, including issues of sovereignty—uncooperative nations could include cases where time or other operation constraints did not allow for permission for the strike to be obtained. There is precedent for this type of action—as retaliation against terrorist outrages in the 1990s, the Clinton administration authorized cruise-missile strikes on targets with terrorist connections. More recently the United States has been using armed UAVs (see next chapter) to target terrorists in the Middle East and tribal regions of Pakistan that seem relatively uncontrolled by the Pakistani government, but has come under criticism that the small munitions employed still cause excessive collateral damage. A DEW-based strike weapon would offer an unparalleled level of precision, the ability to pick out only the guilty parties from a crowd. It must, however, be coupled with real-time targeting, though instead of a limitation this could be another advantage to this concept. Cruise missiles take time to strike—a laser or other form of EM energy utilized as the kill mechanism of a DEW would act almost instantly—meaning a targeting system with sufficient resolution to positively ID a human size target would also give immediate postattack analysis of its results.

It is presently clear that near-term deployment of higher-energy DEW capabilities is unlikely. Chemical HELs such as the ABL and THEL have conceptual difficulties, among them the need for a chemical reactants supply. Purely electrical HELs are a less-mature technology that is still years before reaching the power levels demonstrated by the troubled ABL and THEL programs. Problem-free development is practically unheard of in the creation any complex systems of systems. DEW development has faced additional challenges from both a checkered history, and perceived “newness.” The lack of operation experience feeds both the overselling of capabilities and paranoia over its seemingly controversial aspects. These factors work against acceptance of DEW as a useful military technology outside of a few niche applications. However, it is these niche applications that may very well prove the robustness and other operational qualities needed in a weapon system.

Notes

1. IEEE Global History Network, “Theodore H. Maiman,” http://www.ieeeghn.org/wiki/index.php/Theodore_H._Maiman.

2. Doug Beason, The E-Bomb (Cambridge, Massachusetts: Da Capo Press, 2005), 59.

3. “Charles H. Townes—Biography,” Nobelprize.org, June 1, 2012, http://www.nobelprize.org/nobel_prizes/physics/laureates/1964/townes-bio.html.

4. Rudiger Paschotta, “Beam Quality,” in Encyclopedia for Photonics and Laser Technology, October 2008. http://www.rp-photonics.com/beam_quality.html.

5. Doug Beason, The E-Bomb (Cambridge, Massachusetts: Da Capo Press, 2005), 64.

6. Find press release, preferably USN for January 2011 breakthrough/contracts/work on FEL.

7. Note that GPS guidance is cheaper, but less accurate due to inaccuracies inherent to GPS. For both the skill of the operator must also be taken into account.

8. Note that the first DARPA challenge resulted in no winners as no competitor was able to complete the course, the second did have several vehicles successfully navigate the desert, and the final one had vehicles successfully navigating an urban scenario.

9. Acknowledge possible incidents of intentional blinding by lasers, such as the Chinese ZM-87 portable laser disturber, and incident where Russian forces were suspected of using a blinding laser against NATO peacekeepers in Kosovo.

10. Missile Defense Agency, “Airborne Laser Test Bed Successful in Lethal Intercept Experiment,” February 11, 2010, http://www.mda.mil/news/10news0002.html.

11. Department of Defense, “DoD News Briefing with Secretary Gates from the Pentagon,” April 6, 2009, http://www.defense.gov/transcripts/transcript.aspx?transcriptid=4396.

12. Ibid.

13. Federation of American Scientists, “Airborne Laser,” http://www.fas.org/spp/starwars/program/abl.htm.

14. William J. Broad, “U.S. and Israel Shelved Laser as a Defense,” New York Times, July 30, 2006, http://www.nytimes.com/2006/07/30/world/middleeast/30laser.html?_r=1.

15. Northrop Grumman, “Northrop Grumman Laser ‘Firsts’,” http://www.as.northropgrumman.com/by_capability/directedenergy/laserfirsts/index.html.

16. Defense Science Board, Report of Defense Science Board Task Force on Directed Energy Weapons, December 2007, http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA476320

17. Ibid.

18. Department of Defense. Report of Defense Science Board Task Force on High Energy Laser Weapon Systems Application, June 2001, http://www.acq.osd.mil/dsb/reports/rephel.pdf.

19. Defense Science Board, Report of Defense Science Board Task Force on Directed Energy Weapons, December 2007, http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA476320.

20. Global Security, “Mobile Tactical High Energy Laser,” http://www.globalsecurity.org/space/systems/mthel.htm.

21. Moore's Law specifically postulates that the number of transistors found in common (mass produced) integrated circuits (ICs) doubles every two years. Eventually physics will prevent transistor-based logic circuits from getting any smaller, though smaller transistors are not the only method to double numbers on an integrated circuit (bigger ICs, multilayered ICs, etc.).

22. Amos Harel and Avi Issacharoff, “Top Official: Israel Gave No Guarantees In Exchange for Gaza Truce,” Haaretz, March 14, 2012, http://www.haaretz.com/print-edition/news/top-official-israel-gave-no-guarantees-in-exchange-for-gazatruce-1.418328.

23. Northrop Grumman, “Northrop Grumman Chosen to Increase Efficiency for Next-Generation Military Laser Technology,” September 28, 2010, http://www.irconnect.com/noc/press/pages/news_releases.html?d=202483.

24. United States Navy, “Office of Naval Research Achieves Milestone with Free Electron Laser Program,” January 19, 2011, http://www.onr.navy.mil/Media-Center/Press-Releases/2011/Free-Electron-Laser-Milestone.aspx.

25. Ibid.

26. Ibid.

27. Boeing, “Boeing Advanced Tactical Laser Defeats Ground Target in Flight Test,” September 1, 2009, http://boeing.mediaroom.com/index.php?s=43&item=817.

28. National Institute of Standards and Technology, “CODATA Value: Speed of Light in Vacuum,” http://physics.nist.gov/cgi-bin/cuu/Value?c.

29. Nuclear warship power plants would of course remove this requirement.

30. Commission to Assess United States National Security Space Management and Organization. Report of the Commission to Assess United States National Security Space Management and Organization, January 11, 2001. http://www.space.gov/docs/fullreport.pdf.

31. U.S. EMP Commission. Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Volume 1: Executive Report, 2004, http://www.empcommission.org/docs/empc_exec_rpt.pdf.

32. Ibid.

33. Department of Defense, “Findings of the Nuclear Posture Review,” January 9, 2002, http://www.defenselink.mil/news/Jan2002/g020109-D-6570C.html.

34. Wilson W. S. Wong and James Fergusson, Military Space Power (Santa Barbara: Praeger, 2010), 97.

35. David Fulghum, “For Now JSF Will Not Embrace Electronic Attack,” Aviation Week, January 23, 2012, http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_01_23_2012_p24–415796.xml.

36. Carlo Kopp, “The Electromagnetic Bomb—A Weapon of Electrical Mass Destruction,” Air & Space Power Journal, 1996, http://www.airpower.maxwell.af.mil/airchronicles/cc/apjemp.html.

37. Ibid.

38. Department of the Air Force, Counter-Electronics High Power Microwave Advanced Missile Project (CHAMP) Joint Capability Technology Demonstration (JCTD), October 18, 2008, https://www.fbo.gov/index?s=opportunity&mode=form&id=e2daa9dccf59c9887810286dc9909d54&tab=core&_cview=1.

39. Ibid.

40. Boeing, “Boeing Awarded Contract to Develop Counter-Electronics HPM Aerial Demonstrator,” May 15, 2009 http://boeing.mediaroom.com/index.php?s=43&item=656.

41. In November of 2002 two shoulder-fired missiles were fired at an airliner taking off from Mombasa, Kenya. Neither missile hit the airliner, which proceeded to Israel.

42. Doug Beason, The E-Bomb (Cambridge, Massachusetts: Da Capo Press, 2005), 57.

43. The usage of the word “kinetic” here refers to destructive, as opposed to “energy of motion,” which is the physics definition that shows up elsewhere in this book.

44. Jim Garamone, American Forces Press Service, “CENTCOM Charts Operation Iraqi Freedom Progress,” March 25, 2003, http://www.defense.gov/news/newsarticle.aspx?id=29230.

45. ‘Less than Lethal’? The Use of Stun Weapons in US Law Enforcement, 2008, http://www.amnesty.org/en/library/info/AMR51/010/2008/en.

46. Noah Shachtman, “U.S. Testing Pain Ray in Afghanistan (Updated Again),” Wired, June 19, 2010, http://www.wired.com/dangerroom/2010/06/u-s-testing-painray-in-afghanistan/.

47. Passive millimeter wave sensors actually work off of the energy radiated by all objects, including people.

48. Department of Defense Non-Lethal Weapons Program, “Active Denial System Fact Sheet,” http://jnlwp.defense.gov/pressroom/adt.html.

49. Ibid.

50. Sharon Weinberger, “No Pain Ray Weapon for Iraq (Updated and Bumped),”

Wired, August 30, 2007, http://www.wired.com/dangerroom/2007/08/no-pain-ray-for/.

51. Department of Defense Non-Lethal Weapons Program, “Active Denial System Fact Sheet,” http://jnlwp.defense.gov/pressroom/adt.html.

52. David Hambling, “Microwave Weapon Will Rain Pain from the Sky,” New Scientist, July 23, 2009, http://www.newscientist.com/article/mg20327185.600-microwave-weapon-will-rain-pain-from-the-sky.html.

53. Department of Defense Non-Lethal Weapons Program, “Active Denial System Fact Sheet,” http://jnlwp.defense.gov/pressroom/adt.html.

54. John M. Kenny, et al., A Narrative Summary and Independent Assessment of the Active Denial System, The Human Effects Advisory Panel, February 2011 http://jnlwp.defense.gov/pdf/heap.pdf.

55. Ibid.

56. Raytheon, “Silent Guardian” online sales brochure, http://www.raytheon.com/capabilities/products/stellent/groups/public/documents/content/cms04_017939.pdf.

57. Alvin Toffler and Heidi Toffler, War and Anti-War (New York: Little, Brown and Company, 1993), 129–30.

58. Ian Sample, “Pentagon considers ear-blasting anti-hijack gun,” New Scientist, November 14, 2001, http://www.newscientist.com/article/dn1564.

59. British Broadcasting Corporation, “Calls to Ban ‘Anti-Teen’ Device,” February 12, 2008, http://news.bbc.co.uk/2Zhi/uk_news/7240180.stm.

60. Convention on Certain Conventional Weapons, 1980, http://treaties.un.org/Pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XXVI-2&chapter=26&lang=en.

61. Jane's Information Group, “Laser weapons (China), Defensive weapons,” http://www.janes.com/articles/Janes-Strategic-Weapon-Systems/Laser-weapons-China.html.

62. Franklin Fisher, “U.S. Says Apache Copters Were Targeted by Laser Weapons Near Korean DMZ,” Stars and Stripes, May 14, 2003, http://www.stripes.com/news/u-s-says-apache-copters-were-targeted-by-laser-weapons-near-korean-dmz-1.9753.

63. Federal Aviation Administration, “The Effects of Laser Illumination on Operational and Visual Performance of Pilots during Final Approach,” June 2004, http://www.faa.gov/library/reports/medical/oamtechreports/2000s/media/0409.pdf.

64. Arms Control Association, “U.S. Test-Fires ‘MIRACL’ at Satellite Reigniting ASAT Weapons Debate,” Arms Control Today, October 1997, http://www.armscontrol.org/act/1997_10/miracloct.

65. Warren Ferster and Colin Clark, “NRO Confirms Chinese Laser Test Illuminated U.S. Spacecraft,” Space News, October 3, 2006, http://www.spacenews.com/archive/archive06/chinalaser_1002.html.

66. David Hambling, “US Boasts of Laser Weapon's ‘Plausible Deniability’,” New Scientist, August 12, 2008, http://www.newscientist.com/article/dn14520-us-boasts-of-laser-weapons-plausible-deniability.html.