 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.
