When the the US enter wold war 2?

The United States entered World War II on December 7, 1941, following the surprise attack by Japan on Pearl Harbor, Hawaii. This attack led to a declaration of war against Japan on December 8, 1941. Subsequently, Germany and Italy declared war on the U.S. on December 11, 1941, prompting the U.S. to enter the conflict on both the Pacific and European fronts.