NATO is coming under increasing pressure to investigate possible health risks associated with the use of depleted-uranium ammunition. A number of "Balkans Syndrome" cases have raised fears that the munitions exposed soldiers and civilians to unsuspected danger. Thus far, the threat is more imagined that real. There is no evidence of a link between the use of DU munitions and sickness in service personnel. Nonetheless, a full investigation is required. Questions already swirl around the use of force; there is no need to add to the controversies.

Depleted-uranium ammunition is, as the name suggests, made from the material leftover when natural uranium is enriched to make nuclear fuel or a nuclear warhead. Because the metal is 1.7 times denser than lead, it makes an effective armor-penetrating, tank-busting weapon. (For the same reason, it is sometimes used to reinforce armor.) It vaporizes on contact, which means it will ignite fuel or other flammable objects. It is also mildly radioactive.

DU weapons debuted in the Persian Gulf War in 1991. Military planners were so impressed with their lethality that they called the munitions "silver bullets" in subsequent reports; eight countries added the weapon to their arsenals. The United States used 320 tons of DU weapons in the Gulf War, NATO fired 10,000 rounds of DU shells in Bosnia in 1994-95, and another 31,000 rounds in the Kosovo conflict in 1999. In total, about 12 tons were used in Balkan conflicts.