Japan did not surrernder. When Truman dropped the bomb the word was put out that the US had scores of atomic weapons. We actually had about 3 or 4. But Japan was convinced that we had enough atomic bombs to destroy their entire population. Some Japanese commanders did not believe we had that many and wanted to keep fighting.
What Israel has not learned is a statement attributed to Joe Stalin.. Stalin said, "In war 25 deaths is a tragedy; 25,000 deaths is a statistic."
The Red Army crashing across the Manchurian border also convinced them the game was up.