Named by someone who clearly hated Maryland, the High Energy Laser Mobile Demonstrator (HEL MD) hit 90 incoming mortar rounds and UAVs with a 10 kW laser in November and early December during tests at White Sands Missile Range in New Mexico. HEL MD has been in development since 2011 (though the laser and truck separately have been in the works for years), and this successful demonstration suggests laser warfare may be getting closer to reality.
Military lasers are the latest evolution in "not getting killed" technology. Defense and offense in war tend to be cyclical--for a while, weapons are very good getting through to their targets, but then someone invents better armor, which works until a new weapon is made. Since the advent of gunpowder, really, offensive weapons have outmatched defenses. It's simply easier and cheaper to fire many relatively inexpensive explosives at a target than it is to fire pricey guided missiles to stop attacks in midair. Israel's Iron Dome system, probably the best known missile-intercepting system right now, regularly fires $40,000 missiles to stop $1,000 rockets.
Lasers may level the playing field a bit. They move at the speed of light, which means they can hit an airborne object almost as soon as that object is detected. Mortar shells, cheaper even than the $1,000 rockets, are still more expensive than the approximately $1 it costs to destroy them with a laser. The U.S. Navy plans to test a similar laser, mounted on the USS Ponce, in 2014, which could be useful against swarming boat attacks or incoming missiles.
The HEL MD fired a 10 kW laser at several targets, successfully "engaging" mortar shells and drones. In the future, it should be able to engage cruise missiles, rockets, and artillery. While the use of "engaging" indicates that the laser isn't quite ready to destroy targets, the targeting tools attached to the laser are the real success story, as they managed accurately aim the laser at moving targets.
Future plans for the HEL MD include tests with a 50 kW laser and then a 100 kW laser. If these are successful, and the laser proves feasible, it's possible that enemies trying to fire explosives at American troops in the future will find their attacks halted in midair.