Question

why America entered world war 2?​

Answer 1

Although the war began with Nazi Germany's attack on Poland in September 1939, the United States did not enter the war until after the Japanese bombed the American fleet in Pearl Harbor, Hawaii, on December 7, 1941.

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Answer 2

America entered world war 2  in response to what was claimed to be a series of provocations by the U.S.A government.