部分的核実験禁止条約
The signing of the Partial Nuclear Test Ban Treaty in 1963 and the Outer Space Treaty in 1967 prevented future exploration of the concept of detonating a nuclear device on the Moon. By this time, both the United States and the Soviet Union had performed several high-altitude nuclear explosions, including those of Operation Hardtack I, Operation Argus, Operation Dominic I and II, and The K Project.