The Nuclear Test Ban Treaty was the proudest accomplishment of President Kennedy's one thousand days in the White House. It prohibited nuclear testing in the atmosphere, in space or under the oceans. The treaty was signed by more than one hundred nations, Red China and France notably excepted. Such a treaty had been a goal of United States policy for five years. In mid-1963 a sudden change of heart by the Soviet Chairman Khrushchev made the treaty possible. Its ratification by the U.S. Senate was preceded by exhaustive hearings, lengthy debate and wide public discussion. The Secretary of Defense stated that the treaty would aid national defense but scientists and military leaders admitted it would involve serious risks. Most opinion on the treaty tended to discount the risks as being overshadowed by political gains which might result from further Russian-American cooperation. The critical question prior to the hearings was the position of the Chiefs of the military services, some of whom were skeptical of the treaty. Massive Russian atmospheric tests had broken the previous moratorium on testing, and they had not been equaled by American tests. Superior testing might have provided the Russians with superior knowledge of heavy and high altitude explosions and made possible the disabling of American weapons and communications in the air and under the ground. Senators who heard all the secret testimony before the Armed Services Committee tended to agree. Since the treaty could scarcely be ratified without the support of the military Chiefs, the President worked by various means to gain it. To do so it was necessary for him to accept a compromise worked out by Senator Jackson. He promised to reinstate a vigorous program of underground testing, which he had renounced in June, and to establish a standby facility for use in case the Russians broke the treaty as they had broken the previous moratorium. Conditional approval by the Joint Chiefs of Staff deprived opponents of a recognized authority for their stand, except for the notable testimony of Dr. Edward Teller. After ratification interest in the treaty and in nuclear problems, as well as in disarmament, subsided rapidly. Further gestures toward Russian-American cooperation resulted in dismal failure some weeks before the assassination of President Kennedy. While the treaty was hailed as a great psychological and symbolic triumph over the dangers of nuclear weapons, subsequent events have cast doubt upon its continuing value. France, and especially China, continued to test, but the treaty may have slowed the accumulation of radioactive fallout.