It was ultimately to speed up Japan’s route to surrender during WW2. They wanted to end the war as soon as possible and by threatening, and eventually going about bombing the country, they thought it would make Japan surrender quicker. It was also thought that by bombing Japan, it would drastically reduce the deaths of many American soldiers that partook in that war. But instead, by bombing Hiroshima and Nagasaki, America killed more than 100,000 innocent Japanese civilians in order to save their own people. America also wanted to impress the Soviet Union (Russia) at the time as SU were preparing to join WW2 against Japan, so by impressing them, they had a chance at forming an alliance with SU. Another point is that America had these great bombs that they wanted to test and so specifically testing them in Hiroshima and Nagasaki was a good call for them due to the flat terrain. This allowed America to see just how powerful and destructive their atomic bombs were, proving just how effective it was instead of testing on uneven terrains as they would not have worked as best as they could have.