Directed energy weapons (DEWs), sometimes called E-weapons, include any type of weapon that forgoes use of a projectile in attacking the target. These include lasers, plasma, and various types of particle beams. Frequently, these types of weapons are constructed to be nonlethal. For example, the Active Denial System, which has recently been deployed to Iraq, uses a nonlethal microwave laser.
Because it is the most thoroughly tested and seriously deployed directed energy weapon today, let's examine the Active Denial System. This vehicle-mounted system uses a microwave laser at 95 GHz to penetrate human skin at a depth of less than 1/64th of an inch. The result is an extremely painful burning sensation that causes the target to move away from the team as quickly as possible. The range is up to 1 km (0.62 mile). In contrast to a conventional microwave oven, which operates at 2.4 GHz, this weapon is more energetic but has less penetration depth.
Despite its nonlethality, the use of directed energy weapons brings up ethics questions. What if, for whatever reason, the target is unable to move out of the path of the beam? The use of directed energy for crowd dispersal in riot situations is particular worrisome. However, no matter how you look at it, a nonlethal microwave beam is clearly preferable to a life-ending bullet, the current standard for peacekeeping worldwide.
Directed energy has also been considered for use as an anti-missile system to protect critical infrastructure. This falls under the research project called THEL (Tactical High Energy Laser), an US$89 million project that has successfully shot down 25 Katyusha rockets during test runs. The system has not yet been deployed in a military context, but might one day form the basis of an effective missile intercept system.
Another application of directed energy is in the form of a laser designed to dazzle rather than attack the opponent. The large but handheld PHASR system has been developed for this purpose. It projects a series of bright laser lights specifically designed to overstimulate the brain and cause disorientation. An ethics concern has been raised for the use of this weapon against people with epilepsy.