Albania once possessed a stockpile of weapons of mass destruction. This stockpile of chemical weapons included of mustard agent, lewisite, adamsite, and chloroacetophenone. Albania was among the initial countries who signed the Chemical Weapons Convention (CWC) in 1993. The treaty, which came into force in 1997, requires the declaration of chemical stockpiles, and the destruction of all chemical weapons, delivery systems and production facilities. One of only six nations to declare a stockpile, Albania made its declaration in March 2003, after the discovery, in December 2002, of 600 bulk containers of chemicals in an abandoned bunker. The material was probably acquired by Communist leader Enver Hoxha in the mid-1970s from China although no documentation was found.