Hi there!
The Japanese soldiers and their leaders was refusing to give their fight. American soldiers and the Americans were worry because of that four year war. The Japanese thought they would win since they used to have a lot of military, I believe around 2 million stations.
Harry Truman which was the 33rd President of the United States, after the death of Franklin Roosevelt had a challenge. For Truman, the choice whether or not to use the atomic bomb was the most difficult decision of his life because he wanted the war to be end but Japanese was like let keep going.
Regardless, the United States remains the only nation in the world to have used a nuclear weapon on another nation.
-----------------------------------------------------------------------------------------
My advice to you is to read about word war and do some research, this will help you a lot.
I hope that help!