For use in time of emergency, the government of the United States of America and the government of the Union of Soviet Socialist Republics established a direct communications link between the two governments. Although the idea and drafts of a possible hotline system had existed since 1954, the Cuban Missile Crisis of October 1962 provided a final, compelling impetus for the hot-line.
Signed at Geneva on June 20, 1963. Entered into force June 20, 1963.
The link was improved through on agreement signed and entered into force on September 30, 1971. It was again expanded and technologically improved with the Hot Line Expansion Agreement between United States and Soviet Union which was signed and which entered into force on July 17, 1984