Bohr 's evidence came from an interpretation of a letter he received from a Soviet friend and scientist in Russia , which he showed to the British security services . He reasoned that the longer the United States and Britain hid their nuclear advancements , Russia would feel increasingly threatened and more inclined to speed up their effort to produce an atomic bomb of their own . With the help of U.S. Supreme Court justice Felix Frankfurter , Bohr met with the President of the United States , Franklin D. Roosevelt , who was initially sympathetic to his ideas about controlling nuclear weapons on 26 August 1944 ; but Churchill was adamantly opposed to informing the Soviet Union of such work . At the Second Quebec Conference in September 1944 , Roosevelt sided with Churchill , deciding that it would be upon the nation 's best interest to keep the atomic bomb project a secret . Moreover , they decided Bohr was potentially dangerous and specific security measures must be made in order to prevent him from leaking information to the rest of the world , Russia in particular
Second Quebec Conference
Second Quebec Conference
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