On March 2, 1962, in a national address, President John F. Kennedy announced that he had authorized the Atomic Energy Commission and the Department of Defense to conduct the first U.S. nuclear tests in three years. In 1958, the U.S., the U.S.S.R., and Great Britain had agreed to suspend nuclear testing for one year. After the year passed, a voluntary moratorium continued until it was broken by the Soviets in September 1961. On April 25, 1962, the U.S. resumed nuclear testing in the atmosphere with the explosion of a hydrogen bomb near Christmas Island in the Pacific. A series of additional tests followed during that summer. The next year, the superpowers signed the Moscow Agreement, which banned testing in the atmosphere, in space, and underwater. In later decades, the superpowers agreed to limit and then reduce their massive stockpiles of nuclear weapons with the SALT and START agreements.