One of the first major treaties designed to limit the spread of nuclear weapons goes into effect as the Soviet Union ratifies an agreement banning nuclear weapons from outer space. The United States, Great Britain, and several dozen other nations had already signed and/or ratified the treaty.
With the advent of the so-called "space race" between the United States and the Soviet Union, which had begun in 1957 when the Russians successfully launched the Sputnik satellite, some began to fear that outer space might be the next frontier for the expansion of nuclear weapons. To forestall that eventuality, an effort directed by the United Nations came to fruition in January 1967 when the United States, Great Britain, the Soviet Union, and dozens of other nations signed off on a treaty banning nuclear weapons from outer space. The agreement also banned nations from using the moon, other planets, or any other "celestial bodies" as military outposts or bases.
The agreement was yet another step toward limiting nuclear weapons. In 1959, dozens of nations, including the United States and the Soviet Union, had agreed to ban nuclear weapons from Antarctica. In July 1963, the Limited Test Ban Treaty was signed, banning open-air and underwater nuclear tests. With the action taken in May 1967, outer space was also officially declared off-limits for nuclear weapons.