[en] In 1999 the Balkan's conflict lead NATO war planes to leave 10x10³ kg of depleted uranium (DU) in the environment of Kosovo and neighbouring states (UNEP, 2001). DU behaves in the same manner in the environment as natural uranium and it can be traced with isotopic analysis due to the fact that DU has the isotopic composition of 0.2% ²³⁵ U and 99.8% 2³⁸ U as opposed to natural uranium which has 0.7% 2³⁵ U and 99.3% 2³⁸ U. DU is a waste product of the nuclear industry which enrich nuclear fuel by 2³⁵ U. Large stock piles of DU therefore exist in countries that produce nuclear energy and/or nuclear weapons. The DU is given to the weapons industry for free (or cheap) and has been a popular choice for armour penetrating arsenal due to the high density of uranium (19 g cm^-3 ) and therefore its high penetrating power. Indeed the arsenal used in Kosovo consisted of DU penetrators that were shot from A-10 aeroplanes. They weigh roughly 300 g and have the shape of a fat 9 cm long pencil. (author)