UK Develops Nuclear Weapons

Date: May 12, 1948 • Location: London, United Kingdom

The United Kingdom publicly announced that it was independently developing nuclear weapons, after the US Atomic Energy Act of 1946 ended cooperation on the matter.

High Explosive Research (HER) was the British project to develop atomic bombs independently after the Second World War. This decision was taken by a cabinet sub-committee on 8 January 1947, in response to apprehension of an American return to isolationism, fears that Britain might lose its great power status, and the actions by the United States to withdraw unilaterally from sharing of nuclear technology under the 1943 Quebec Agreement. The decision was publicly announced in the House of Commons on 12 May 1948.