The Treaty on the Prohibition of the Emplacement of Nuclear Weapons and Other Weapons of Mass Destruction on the Seabed and the Ocean Floor and in the Subsoil Thereof is signed in Washington, Moscow, and London.

South Africa joins the Peaceful Nuclear Explosions Program and begins its weapons program in a search for nuclear plowshares technology. 

The first Poseidon submarine-launched ballistic missile (SLBM) are introduced by the United States. 

The Agreement on Measures to Reduce the Risk of Outbreak of Nuclear War Between the U.S. and USSR is signed in Washington and enters into force. Under the Agreement, both states pledge to take measures each considers necessary to safeguard against accidental use of nuclear weapons, to make arrangements for immediate notification should a risk of nuclear war arise from such incidents, and to provide advanced notification of any planned missile launches beyond the state’s territory. The Hot Line Modernization Agreement between the U.S. and the USSR to improve the Hot Line is also signed and enters into force. [see June 20, 1963]