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.
Однако ранее как США, так и СССР провели несколько высотных ядерных взрывов, в том числе операции Hardtack I, Argus, Dominic, а также The K Project.