The manufacture of depleted uranium (DU) ammunition is a prototypical Cold War arms race story. The Pentagon reported in the 1970s that the Soviet military had developed armor plating for Warsaw Pact tanks that NATO ammunition couldn't penetrate, and began searching for material to make harder bullets, bombs, and shells. After testing various metals, ordnance researchers settled on depleted uranium, a low-level radioactive waste left over from making nuclear fuel and bombs. DU ammunition, which scorches through metal targets, is now supplied to arsenals in the U.S. and abroad which also continue to store “conventional” ammunition. DU shells, when fired, leave a radioactive trail of toxic dust that still lies in parts of Kuwait and Iraq where they were first fired in combat during the 1991 Gulf War. Prohibited from use in training anywhere overseas, it is restricted certain installations in the United States. Citing serious health risks, the Pentagon requires moon-suit type protective gear when approaching anything hit with DU ordnance.