In a landmark agreement, three Cold War behemoths put aside their differences, as the United States, the United Kingdom, and the Soviet Union signed the Partial Nuclear Test Ban Treaty, outlawing nuclear tests in the atmosphere, outer space, and underwater. This groundbreaking accord marked a significant step towards reducing the risk of nuclear war, signaling a thaw in the Cold War's icy grip. The treaty's signing was a major diplomatic victory for the Kennedy administration, as it effectively restricted the development of new nuclear weapons, fostering a sense of détente among the signatory nations.