During World War II, the United States was a member of the Allies. Axis. European Theater. Pacific Theater

During World War II, the United States of America was a member of the Allies in the Pacific Theater. Although this area was their primary place of fighting, the eventually joined the European theater as well and fought hard and difficult battles there.

Allies, which was name of the countries fighting against the Axis powers during World War II. During the war, the Allies used the term "United Nations". This return after the war was used for naming the international organization, which aims at ensuring peace and security in the world. First members of Allies were UK, France and Poland. (European Theater and Pacific Theater are not organization but two major maxi areas where action of WW2 took place, USA fought in both)