Malden Island, sometimes called Independence Island in the 19th century, is a low, arid, uninhabited atoll in the central Pacific Ocean, about 39 km2 (15 sq mi) in area. It is one of the Line Islands belonging to the Republic of Kiribati. The lagoon is entirely enclosed by land, though it is connected to the sea by underground channels, and is quite salty.
A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon, utilizing nuclear fusion. The most destructive weapons ever created, their yields typically exceed first-generation nuclear weapons by twenty times, with far lower mass and volume requirements. Characteristics of fusion reactions can make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material. Its multi-stage design is distinct from the usage of fusion in simpler boosted fission weapons. The first full-scale thermonuclear test was carried out by the United States in 1952, and the concept has since been employed by at least the five NPT-recognized nuclear-weapon states: the United States, Russia, the United Kingdom, China, and France.
Operation Grapple was a set of four series of British nuclear weapons tests of early atomic bombs and hydrogen bombs carried out in 1957 and 1958 at Malden Island and Kiritimati in the Gilbert and Ellice Islands in the Pacific Ocean as part of the British hydrogen bomb programme. Nine nuclear explosions were initiated, culminating in the United Kingdom becoming the third recognised possessor of thermonuclear weapons, and the restoration of the nuclear Special Relationship with the United States in the form of the 1958 US–UK Mutual Defence Agreement.