Prior to the Hiroshima bombing, all that the US had told the USSR about the atom bomb was that they had developed a "new weapon of unusual destructive force" (T

Prior to the Hiroshima bombing, all that the US had told the USSR about the atom bomb was that they had developed a "new weapon of unusual destructive force" (Truman to Stalin at the Potsdam conference.) As it happens, Stalin knew all about it through espionage, but as the US government was unaware of this, we cannot deduce, from what Stalin had been told by the US government, that the US government's position was that using atom bombs against Japan would have no influence on Stalin's thinking. Furthermore, we have evidence, from the diaries and correspondence of Truman, Stimson and others, that they were concerned about Stalin's territorial intentions, and expressed the hope that the US's demonstration of the atom bomb would curb them. Whether that led to at least a tacit secondary goal, of checking the USSR by leaving no doubt about the US's willingness to use atomic weapons in circumstances it deemed necessary, is an open question debated by historians to this day.