To lessen the threat of an accidental nuclear war, the United States and the Soviet Union agree to establish a "hot line" communication system between the two nations. The agreement was a small step in reducing tensions between the United States and the USSR following the October 1962 Missile Crisis in Cuba, which had brought the two nations to the brink of nuclear war.
The need for nearly instantaneous and full-time communication between the U.S. and Soviet governments became apparent during the Cuban Missile Crisis of October 1962. The United States had discovered that the Soviets were building missile sites in Cuba capable of firing missiles with nuclear warheads. Eventually, the administration of President John F. Kennedy instituted a naval "quarantine" around Cuba to block the delivery of such missiles. Possible nuclear conflict was avoided only when Soviet leader Nikita Khrushchev agreed that his country would not install nuclear weapons in Cuba. In exchange, the United States vowed not to threaten the sovereignty of Cuba. Prior to the settlement, the world sat through several very tense days of waiting to see whether World War III would begin. In an attempt to reduce the tensions brought about by the October 1962 crisis, and hopefully avert any future misunderstandings that might trigger a nuclear conflict, the United States and the Soviet Union agreed in June 1963 to establish a "hot line." It would be a 24-hour-a-day communications link between Washington, D.C., and Moscow. President Kennedy declared, "This age of fast-moving events requires quick, dependable communication in time of emergency." The agreement was a "first step to help reduce the risk of war occurring by accident or miscalculation."
The system was put into place a few months after the agreement was signed. Beyond serving as a dramatic prop in movies such as Fail Safe (or a comedic prop in the film Dr. Strangelove), the communication line has--thankfully--never had to be used to avert a nuclear war.