page_title: Nuclear weapons and the United Kingdom
section_title: US nuclear weapons
hierarchical_section_title: Nuclear weapons and the United Kingdom / History / US nuclear weapons
caption_attribution_description: Douglas GAM-87 Skybolt air-launched ballistic missile (prototype or engineering model of cancelled missile program). Photo taken at the RAF Museum Cosford, Shropshire, England.
context_page_description: In 1952 the United Kingdom became the third country to develop and test nuclear weapons, and is one of the five nuclear-weapon states under the Treaty on the Non-Proliferation of Nuclear Weapons.
  The UK initiated a nuclear weapons programme, codenamed Tube Alloys, during the Second World War. At the Quebec Conference in August 1943, it was merged with the American Manhattan Project. The British contribution to the Manhattan Project saw British scientists participate in most of its work. The British government considered nuclear weapons to be a joint discovery, but the American Atomic Energy Act of 1946 restricted other countries, including the UK, from access to information about nuclear weapons. Fearing the loss of Britain's great power status, the UK resumed its own project, now codenamed High Explosive Research. On 3 October 1952, it detonated an atomic bomb in the Monte Bello Islands of Western Australia in Operation Hurricane. Eleven more British nuclear weapons tests in Australia were carried out over the following decade, including seven British nuclear tests at Maralinga in 1956 and 1957.
context_section_description: Production of British nuclear weapons was slow and Britain had only ten atomic bombs on hand in 1955 and just fourteen in 1956. At the three-power Bermuda Conference with Eisenhower in December 1953, Churchill, suggested that the United States allow Britain to have access to American nuclear weapons to make up the shortfall. The provision on American weapons was called Project E. The agreement was confirmed by Eisenhower and Macmillan, who was now the Prime Minister, during their March 1957 meeting in Bermuda, and a formal Memorandum of Understanding (MOU) was signed on 21 May 1957.
  Four squadrons of English Electric Canberra bombers based in Germany were equipped with US Mark 7 nuclear bombs stored at RAF Germany bases. There were also four squadrons of nuclear-armed Canberras based in the UK, which were capable of carrying either the Mark 7 or Red Beard. They too were assigned to the SACEUR in October 1960. The planned V-bomber force was reduced to 144 aircraft, and it was intended to equip half of them with Project E weapons, so 72 Mark 5 nuclear bombs were supplied for the V-bombers. When the MDA came into force, the US agreed to supply the V-bombers with megaton weapons in place of the Mark 5, in the form of Mark 15 and Mark 39 nuclear bombs.
  Under the Project E MOU, US personnel had custody of the weapons. This meant they performed all the tasks related to their storage, maintenance and readiness. The bombs were stored in Secure Storage Areas (SSAs) on the same bases as the bombers which British staff were not permitted to enter. It was therefore impossible to store British and Americans bombs together in the same SSA. US custody also created operational problems. The procedure for handing over the bombs added an extra ten minutes to the bombers' reaction time, and the requirement that US personnel had guardianship of the weapons at all times meant that neither they nor the bombers could be relocated to dispersal airfields as the RAF desired. The operational restrictions imposed by Project E "effectively handed the US government a veto over the use of half of Britain's nuclear deterrent".
  The Air Council decided on 7 July 1960 that Project E weapons would be phased out by December 1962, by which time it was anticipated that there would be sufficient British megaton weapons to equip the entire strategic bomber force. Project E weapons were replaced by British Yellow Sun bombs. Problems encountered in the development Red Beard bomb meant that the replacement of kiloton weapons took longer. The Air Ministry decided to replace the Canberras with Valiants as the long-range Vulcan and Victor V bombers became available. A Valiant squadron at RAF Marham was assigned to SACEUR on 1 January 1961, followed by two more in July. The UK-based Canberra squadrons were then disbanded. Each of the 24 Valiants was equipped with two Project E Mark 28 nuclear bombs. These were replaced by the newer Mark 43 nuclear bombs in early 1963. The Valiants were withdrawn from service in 1965.
  Project E nuclear warheads were also used on the sixty Thor Intermediate Range Ballistic Missiles (IRBMs) that were operated by the RAF from 1959 to 1963 under Project Emily. During the Cuban Missile Crisis, the RAF's bombers and Thor missiles targeted 16 cities, 44 airfields, 10 air defence control centres and 20 IRBM sites. The RAF high command never warmed to missiles, and always ranked them secondary to the V bomber force. The missile bases were separate from the rest of the RAF and its personnel considered outside the mainstream. Project Emily gave the RAF considerable experience in missile operations, but the 1960 cancellation Blue Streak in favour of the American Skybolt, an air-launched ballistic missile, rendered this expertise of dubious value. An Air Council meeting on 31 May 1962 decided that Project Emily should be terminated by the end of 1963, and the last Thor squadrons were inactivated on 23 August 1963.
  The availability of US weapons and designs under the MDA led to the cancellation of several research projects. Indigo Hammer and the smal
caption: Skybolt missile
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