The main opponents in World War II were the. The United States entered the war on the side of the after the bombing of by in

The main opponents in World War II were the Allied (Great Britain, France, the Soviet Union and the United States) and the Axis (Germany, Italy and Japan). The United States entered the war on the allied side after the bombing of Pearl Harbor by Japan.

Explanation:

World War II was a conflict that involved most of the nations of the world, including all the great powers, organized into two military alliances: the Allies and the Axis. The war involved about 100 million military and was the cause of the death of between 50 to 60 million people, mostly civilians, 3% of the world population of the time; It became the most deadly conflict in human history and the first (and for now only) in which nuclear weapons were used.

Until 1941 the United States did not enter World War II, because its inhabitants saw it as a European war and did not see it right that the country enter the war. However, there was a fact that made the country finally decide to take up arms and enter the conflict at the side of the allies: the attack on Pearl Harbor. The attack on Pearl Harbor was a surprise military offensive by the Imperial Japanese Navy against the United States naval base in Pearl Harbor, Hawaii on the morning of Sunday, December 7, 1941.

The entry of the United States has been the main factor for the victory of the Allies. The Americans had a strong and organized army and a huge military capacity. The first victory of the United States during World War II occurred at the Battle of Midway in 1942, defeating the Japanese Navy.

In 1945, US troops ended the war by using a nuclear weapon, the atomic bomb, for the first time in history. The United States bombed the cities of Hiroshima and Nagasaki, leaving a vast human and natural destruction with nuclear radioactivity, sealing a new stage in the history of mankind.

1: I'm assuming you mean for the U. S. which would be Germany and Japan.

2: After the bombing of Pearl Harbor in Hawaii by Japan, the U. S then joined the Allied forces.