Under the security alliance with the United States, Japan has served as a bulwark against an expansion of the Soviet communist bloc and China's hegemonic ambitions since the end of World War II.

In August 1945, Japan surrendered in the war following heavy casualties, including from U.S. air raids across the country and the U.S. atomic bombings of the Japanese cities of Hiroshima and Nagasaki.

The Allied powers considered dividing Japan. But the United States, wary of the potential rise of the Soviet Union, wanted Japan to recover quickly as a capitalist country. Washington used Japan as a base for containing communism during the Cold War.