The US military has given the first public display of what it says is a revolutionary heat-ray weapon to repel enemies or disperse hostile crowds.
Called the Active Denial System, it projects an invisible high energy beam that produces a sudden burning feeling, but is said to be harmless.
Military officials believe the gun could be used as a non-lethal way of making enemies surrender their weapons.
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The prototype weapon - called Silent Guardian - was demonstrated at the Moody Air Force Base in Georgia.
A beam was fired from a large rectangular dish mounted on a Humvee vehicle.
The beam has a reach of up to 500 metres (550 yards), much further than existing non-lethal weapons like rubber bullets.
It can penetrate clothes, suddenly heating up the skin of anyone in its path to 50C.
But it penetrates the skin only to a tiny depth - enough to cause discomfort but no lasting harm, according to the military.
A Reuters journalist who volunteered to be shot with the beam described the sensation as similar to a blast from a very hot oven - too painful to bear without diving for cover.
http://news.bbc.co.uk/2/hi/americas/6297149.stm