Depleted Uranium
Sorry Lindy, but use of depleted uranium weapons is not regarded as a violation of international law. The material is pretty much innocuous. Because so many people misunderstand the nature of radioactive materials, there's is more hype about DU weapons than is deserved.
The material is used in warheads because it is very hard and able to break through reinforced structures. But the material itself had not been documented to be a serious threat to human health.