1990

The United Nations General Assembly declares 1990s as the Third Disarmament Decade.

June 1
President George Bush and President Mikhail S. Gorbachev sign new protocols to the Threshold Test Ban Treaty and Underground Nuclear Explosions for Peaceful Purposes Treaty which provide for advance notification and onsite inspection of tests above 35 kilotons.

September
Brazilian President Fernando Collor de Mello symbolically closes a nuclear test site.

September 25
U.S. ratifies the Threshold Test Ban Treaty. The Treaty prohibits underground nuclear weapon tests with a yield exceeding 150 kilotons (more than 10 times the yield of the Hiroshima bomb). [see July 3, 1975]

September 27
The last Pershing II missiles leave West Germany.

October
Brazilian President Fernando Collor de Mello formally exposes Brazil's atomic weapons plan.

November 16
The Stockholm Declaration on Preventing Accidental Nuclear War is released.

November 29
Argentine President Carlos Saul Menem and Brazilian President Fernando Collor de Mello sign the Declaration on the Common Nuclear Policy at Foz de Iguazu, Brazil. The Declaration formally renounces nuclear weapons and establishes a framework for the implementation of a bilateral nuclear accounting and inspection arrangement with full IAEA safeguards.

December 4
The United Nations General Assembly adopts the Establishment of a Nuclear-Weapons-Free Zone in the Middle East resolution.

December 11
The Threshold Test Ban Treaty enters into force.