Partial Nuclear Test Ban Treaty

The Partial Nuclear Test Ban Treaty, formally the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, forbids every test detonation of a nuclear weapon except those carried out underground. It is also known as the Limited Test Ban Treaty. Negotiators first aimed at a complete ban, but doubts about detecting underground tests and Soviet objections to intrusive verification made them settle for a partial one. Public alarm over fallout from thermonuclear tests, and the hope of slowing proliferation and the arms race, drove the effort. The Soviet Union, the United Kingdom and the United States signed it in Moscow on 5 August 1963, and it took effect on 10 October 1963; a further 123 states have since become parties and ten have signed without ratifying. It did not stop proliferation, but it set a lasting norm against non-underground testing, and for ratifying parties it was later succeeded by the Comprehensive Nuclear-Test-Ban Treaty.