The correct answer is Americans were tired of war and the US should end it quickly.
At the Potsdam Conference, the three major Allied Powers met to discuss punishments for Germany. Along with this, they also discussed what they should do about Japan since they were still fighting the Allied in the Pacific Ocean. To end this war quickly, the three leaders agreed that Japan should submit to an unconditional surrender.
After Japan refused to the conditions outlined at the Potsdam Confernce, Truman felt that drastic measures must be used. He considered options like a land invasion. However, a D-day style invasion would most likely have caused 500,000 casualties (or more). This could also take months, possibly even a year to end. In order to save American lives and end the war sooner, Truman decided to use bombs on both Hiroshima and Nagasaki.
