Through the 20s and 30s, the Japanese began to expand and invade other countries. This eventually led to the U.S. freezing the trade with Japan because they took control of one of our allies.
Japanese take over Singapore
The U.S. created an embargo on trade with Japan after the Japanese occupied French Indo-China. This embargo caused Japan to lose about 88% percent of their oil importations.
The Japanese attacked Pearl Harbor on December 7th, 1941 and destroyed several of the U.S. battleships. Over 2,000 people were killed in the attack, and almost 1200 were killed one the U.S.S. Arizona.
The Japanese captured about 60,000 prisoners from Britain in February of 1942 when Japan took control of Singapore.
Roosevelt gave a speech soon after the Pearl Harbor surprise attack where he said that December 7th, 1941 will be "a date that will live in infamy." His speech also included a declaration of war against Japan which was quickly approved by congress.
On August 6th, 1945, the U.S. dropped an atomic bomb on the city of Hiroshima, after the Japanese generals refused to surrender. Japan still did not surrender, so another atomic bomb was dropped on the city of Nagasaki 3 days later.