The weapon, mounted on a Humvee vehicle, projects a "focused, speed-of-light millimeter wave energy beam to induce an intolerable heating sensation,'' according to a U.S. Air Force fact sheet. The energy penetrates less than 1/64 of an inch into the skin and the sensation ceases when the target moves out of the beam.

The weapon could be used for crowd control and is effective beyond the range of bullets fired by small arms, Karcher said. The effective range of an AK-47 assault rifle is as far as 273 yards, while an M16A2 rifle has a range of 400 meters.