Military activity is a source of uranium, especially at nuclear or munitions testing sites. Depleted uranium (DU) is a byproduct of uranium enrichment that is used for defensive armor plating and armor-piercing projectiles. Uranium contamination has been found at testing sites in the UK, in Kazakhstan, and in several countries as a result of DU munitions used in the Gulf War and the Yugoslav wars. During a three-week period of conflict in 2003 in Iraq, 1,000 to 2,000 tonnes of DU munitions were used.
Combustion and impact of DU munitions can produce aerosols that disperse uranium metal into the air and water where it can be inhaled or ingested by humans. A United Nations Environment Programme (UNEP) study has expressed concerns about groundwater contamination from these munitions. Studies of DU aerosol exposure suggest that uranium particles would quickly settle out of the air, and thus should not affect populations more than a few kilometres from target areas.