Answer:
Americans found that Japan was trying to attack it and since Japan was on the Axis side, the US joined the Allies to defeat Hitler, Mussolini and Hirohito. They declared war on Japan after the attack on Pearl Harbour, which took the lives of over 2,000 Americans. Back at the US, people were outraged of what Japan had done. It had killed a lot of their people and the US wanted revenge. The US joined Britain and the Allies and inflicted a heavy defeat and got their revenge on Japan at 1945 with nukes.