Screening in English.
On the morning of December 7, Japanese carrier-based planes executed a devastating surprise attack against the U.S. Pacific Fleet at Pearl Harbor, Hawaii. Twenty-one ships were destroyed or temporarily disabled; 323 aircraft were destroyed or damaged; 2,388 soldiers, sailors, and civilians were killed. However, the U.S. aircraft carriers that would play such a critical role in the ensuing naval war in the Pacific were at sea and not anchored at Pearl Harbor.
American opinion, still divided about the war in Europe, was unified overnight by what President Roosevelt called “a date that will live in infamy.” On December 8, Congress declared a state of war with Japan; three days later Germany and Italy declared war on the United States.
Soon after the United States entered the war, the United States, Britain, and the Soviet Union (at war with Germany since June 22, 1941) decided that their primary military effort was to be focused in Europe. Read more in the article The United States in WWII.