Truman didn’t attend Yalta. That was FDR. If Ike and others opposed use of the bomb, they were wrong. If you have a weapon that can end the war, you use it... period. You don’t sacrifice hundreds of thousands of American lives on an invasion of the Japanese mainland.
Not only that, it saved the Soviets (who already took Sakhalin), from entering the fray, which certainly would have resulted in a divided post-war Japan, just like Germany and Korea, and a good chance of a Korea-like Civil War, which no doubt, the US would have been involved in.
Thanks for the correction,meant Potsdam.