It depends on what you mean by "enter" if you want a literal event that prompted a declaration of war by the United States then it was the raid on Pearl Harbor by the Empire of Japan. However, the US had been lending tacit support in the form of material aide (lend lease program) as well as other gestures to the allies for some time before that.
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The US entered WW2 with the bombing of Pearl Harbor by Japan. As soon as we declared war on Japan Germany delcared war on the US. The Germans had an agreement with Japan.
yes it was vital 4 the US 2 enter World War 2 because we needed their help 2 win the war. It turns out tht because of them we won the war.
1941
pearl harbor
No
1941
World War 2
Pearl Harbor
08 Dec 1941
1909 to 1944 The US entered World War 2 in December of 1941.
on decmber 8 1941
World War 2 : Japan.
Japan attacked the US Fleet at Pearl Harbor.