Violet Club was a nuclear weapon deployed by the United Kingdom during the cold war. It was Britain's first operational "high yield" weapon, and was intended to provide an emergency capability until a thermonuclear weapon could be developed from the 1956-1958 Operation Grapple thermonuclear tests conducted on Kiritimati (Christmas Island). In 1953, shortly after the Americans tested a thermonuclear weapon in 1952, followed by the Soviets with Joe 4, and before the UK government took a decision in July 1954 to develop a thermonuclear weapon, the Atomic Weapons Research Establishment at Aldermaston was asked about the possibilities for a very large pure fission bomb with a yield of one megaton.