The Limited Test Ban Treaty (LTBT) is a treaty prohibiting all test detonations of nuclear weapons except underground. It was developed both to slow the arms race (nuclear testing was, at the time, necessary for continued developments in nuclear weapons), and to stop the excessive release of nuclear fallout into the planet's atmosphere. The Treaty was signed and ratified by the governments of the Soviet Union, the United Kingdom, and the United States during the autumn of 1963.