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National Museum of Nuclear Science & History

Hyde Park Aide-Mémoire

The short agreement between President Franklin Roosevelt and British Prime Minister Winston Churchill, dubbed the Hyde Park Aide-Mémoire, was an attempt to ensure nuclear weapons would remain only in the U.S. and Great Britain’s possession. Written in 1944, the agreement also reveals the plans of the two leaders to use the bomb against Japan, as well as Churchill’s immense distrust of Niels Bohr.  

Document Type:
Churchill's Copy of the Hyde Park Aide-Mémoire

1. The suggestion that the world should be informed regarding tube alloys, with a view to an international agreement regarding its control and use, is not accepted. The matter should continue to be regarded as of the utmost secrecy; but when a “bomb” is finally available, it might perhaps, after mature consideration, be used against the Japanese, who should be warned that this bombardment will be repeated until they surrender.

2. Full collaboration between the United States and the British Government should continue after the defeat of Japan unless and until terminated by joint agreement.

3. Enquiries should be made regarding the activities of Professor Bohr and steps taken to ensure that he is responsible for no leakage of information particularly to the Russians.