Nuclear weapons of the United Kingdom

The United Kingdom became the third country (after the United States and the Soviet Union) to develop and, in 1952, test nuclear weapons. The UK is one of nine nuclear-armed states, and one of five recognized by the Treaty on the Non-Proliferation of Nuclear Weapons. As of 2025, the UK possesses a stockpile of approximately 225 warheads, with 120 deployed on its only delivery system, the Trident programme's submarine-launched ballistic missiles. Additionally, United States B61 nuclear bombs have potentially been stored at RAF Lakenheath since 2025. In 2025, the UK announced plans to procure 12 F-35A aircraft capable of delivering B61s.

Trident consists of four Vanguard-classsubmarines, based at HMNB Clyde in Scotland. Each is armed with up to sixteen Trident II missiles, each carrying warheads in up to eight multiple independently targetable re-entry vehicles. Since 1969, the Royal Navy has operated the continuous at-sea deterrent: at least one nuclear-armed ballistic missile submarine always on patrol. Under the Polaris Sales Agreement, the US supplied the UK with Polaris missiles and nuclear submarine technology, in exchange for the general commitment of these missiles to NATO. In 1982, an amendment allowed the purchase of Trident II missiles, and since 1998, Trident has been the only British nuclear weapons system. The UK is the only nuclear-armed country to use exclusively sea-launched nuclear weapons.

UK nuclear command and control launch authority rests with the Prime Minister, or if unreachable a designated deputy, while it is possible the Chief of the Defence Staff holds a veto. In the event of a decapitation strike, handwritten letters of last resort from the Prime Minister are used to instruct submarine crews. UK nuclear weapons have no permissive action links or corresponding launch codes, thus submarine crews may independently launch a nuclear attack.

The UK initiated the world's first nuclear weapons programme, Tube Alloys, in 1941 during the Second World War. At the 1943 Quebec Conference, it was merged with the American Manhattan Project, but collaboration ended in 1946. The UK began an independent programme, High Explosive Research, testing its first nuclear weapon in 1952. In total the UK conducted 45 nuclear tests, 12 in Australia, 9 in the Pacific, and 24 at the Nevada Test Site, with its last in 1991. The UK and France are the only two nuclear-armed countries that have ratified the Comprehensive Nuclear-Test-Ban Treaty.

The British hydrogen bomb programme's success with its Operation Grapple Pacific nuclear testing led to the 1958 US–UK Mutual Defence Agreement. This nuclear Special Relationship has involved the exchange of classified scientific data, warhead designs, and fissile materials. UK warheads are designed and manufactured by the Atomic Weapons Establishment. During the Cold War, the Royal Air Force operated the V bomber fleet for strategic weapons, followed by aircraft in tactical nuclear roles using WE.177 bombs. The RAF also planned to operate the cancelled Blue Streakintermediate-range ballistic missile (IRBM). The RAF also briefly operated Thor IRBMs under US custody, while both the RAF and the British Army of the Rhine operated US-custody tactical bombs, missiles, depth charges and artillery. US Air Force nuclear weapons were stationed in the UK between 1954 and 2008, and from 2025.