Direct energy weapons are a dream come true for military tacticians. Instantaneous and precise, these weapons shoot beams of electromagnetic energy, a nearly inexhaustible power source. Like Star Trek's phasers, they can be throttled up or down to a "stun" setting ro a more lethal "kill."
So why are these weapons not being used in the battle in Iraq? Logistical problems have conspired to keep them off the battlefield. Despite Promise, Energy-Beam Weapons Still Missing from Action (MIT Technology Review, July 13, 2005)