Soon after arriving at the Potsdam Conference in July 1945, U.S. President Harry S. Truman received word that the scientists of the Manhattan Project had successfully detonated the world’s first nuclear device in a remote corner of the New Mexico desert.
On July 24, eight days after the Trinity test, Truman approached Soviet Premier Joseph Stalin, who along with Truman and British Prime Minister Winston Churchill (soon to be succeeded by Clement Attlee) made up the “Big Three” Allied leaders gathered at Potsdam to determine the post-World War II future of Germany.
According to Truman, he “casually mentioned” to Stalin that the United States had “a new weapon of unusual destructive force,” but Stalin didn’t seem especially interested. “All he said was that he was glad to hear it and hoped we would make ‘good use of it against the Japanese,’” Truman later wrote in his memoir, Year of Decisions.