The United States fought the Axis alliance in World War II. The Axis alliance consisted of Germany, Italy, Japan, Hungary, Romania and Bulgaria. These countries fought against the United States and the other members of the Allied forces.
The main countries that formed the Allied forces during World War II were the United Kingdom, the United States, France and the Soviet Union. Some of the other Allied nations included Australia, Canada, Belgium and China. World War II began in 1939 but the United States did not enter the war until the bombings in Pearl Harbor on December 7, 1941. On September 2, 1945 the war officially ended when the Axis powers surrendered.