Remember the old joke about "what if they gave a war and nobody came?" It's not quite as dramatic, but the Pentagon has invested $120 million dollars over the last fifteen years in an "Active Denial System" that nobody wants to use.

The military claims that its so-called "pain ray," which causes a sharp burning sensation, is completely harmless. The radiation penetrates less than half a millemeter into the skin and is a different wavelength from that used in a microwave oven. They would like to see the device employed in place of guns for crowd control and counter-insurgency.

"You want to win the hearts and minds," Colonel Tracy Tafolla of the Pentagon's Joint Nonlethal Weapons Directorate told al Jazeera. "You don't want to kill the people that you're trying to protect."

Unfortunately -- from the military's point of view -- the device has significant limitations. It takes sixteen hours to boot up and loses effectiveness in the rain or snow. But its greatest drawback may be the potential for negative propaganda

"In 2010, it actually was deployed to Afghanistan," Spencer Ackerman of explained. "And then, very, very quickly, General McChrystal, when he was the commander there, sent it back. He was concerned about the propaganda effects, that the Taliban there would be able to say the U.S. is zapping or microwaving Afghans."

In an attempt to win the hearts and minds of the American media, the Pentagon invited a bunch of journalists to the Marine Corps Base in Quantico, Virginia a few weeks ago to feel the effects of the pain ray for themselves. But except for some entertaining jumps and yelps, it is not clear that anything was accomplished by the exercise.

This video was uploaded to YouTube by AlJazeeraEnglish on April 22, 2012.