This satellite dish looking thing adorning the top of the Humvee to the left is the Active Denial System (ADS), more colloquially known as the US Military Pain Beam.
the ADS is a vehicle mounted, less than lethal, directed energy weapon. It has the intended purpose of being used for riot control. It attains said control through the use of a stream of electromagnetic radiation at 95 gigahertz to impart energy to the water molecules in the human skin. If that sounds familiar, it's because your microwave does the exact same thing, only at 2.45 GHz, not 95 GHz, and to a TV dinner, not a human being. It's the same principle, though. The high energy level of the water molecules imparts the sensation of extreme burning, without the permanent damage or bad smell. And with a range of nearly 700 meters, it keeps the operator out of the range of thrown rocks and clubs, the staple weapons of rioters.
In over 10,000 tests of the ADs on humans, there have only been two incidences of serious injury. Both were second degree burns, hardly fatal, or life changing.
This weapons system provides the possibility for less than lethal force to be applied at distances which render the situation controllable. Most less than lethal weapons employed by the military or police force has a range on 25 meters or less. The Self Propelled sponge grenade has the longest range, at 50 meters. The ADS's range is 14 times that.
The ADS has proven itself to be more effective than CS gas in crowd dispersal, because CS has a tendency to incapacitate people and leave them on site, whereas the ADS causes people to flee reflexively. This weapons system would make its money in situations where there previously was no middle ground between lethal force and no force. A prime example would be the Sep 12th, 2004 riots in Baghdad were civilians attempted to loot a damaged Bradley Fighting Vehicle. An Army helicopter ordered the civilians to disperse with his bullhorn, and when they continued to swarm the vehicle, the helicopters dispersed the crowd with the next step up in their arsenal, a 30 mm chain gun. 13 people were killed, including a Palestinian reporter. The ADS could have dispersed the crowd without the need for bloodshed.
The Pain Beam is up for approval to be deployed in country to units. It has already been rejected once before, due to the political controversy over the Abu Gharib abuse scandal. Politicians fear that the ADS will be used maliciously, to burn and torture prisoners. Anyone who's watched Reservoir Dogs knows that torture doesn't require a high tech weapons system, just a razor, gasoline, and a matchbook. And while politicians fear the political backlash of deploying the weapons system in Iraq, I think that this system is far more humane than CS Gas, and certainly more humane than a bullet.