South Africa's dismantled arsenal

South Africa is the only country to have built nuclear weapons and then dismantled them entirely. The apartheid government assembled six gun-type uranium devices between 1979 and 1989 — a seventh was under construction — at the Circle facility near Pretoria, with highly-enriched uranium from the Valindaba plant. The deterrence concept was never to fight with the weapons but to reveal them if the state faced existential threat, compelling Western intervention.

In 1989 the government ordered the program terminated: the devices were dismantled, the HEU melted down and returned to civilian safeguards, and the production lines destroyed. South Africa acceded to the NPT in 1991, and President de Klerk disclosed the former program publicly on 24 March 1993. In August 1994 the IAEA confirmed that six complete devices and one partly built device had been dismantled — to date the only IAEA-verified dismantlement of an indigenous arsenal.

South Africa went on to champion the African Nuclear-Weapon-Free Zone (Treaty of Pelindaba, in force 2009) and was among the first signatories of the Treaty on the Prohibition of Nuclear Weapons.

Pretoria remains the disarmament system's exhibit A: an early TPNW ratifier, a leading voice in the treaty's meetings, and the standing rebuttal to the claim that verified rollback is impossible. It has, however, kept an estimated 220 kg of weapons-grade uranium from the old program at Pelindaba (2015 reporting), declining US-backed efforts to remove or blend it down.