Japan's attack on Pearl Harbor took place on December 7, 1941. The United States military suffered 19 ships damaged or sunk, and 2,403 people were killed. Its most significant consequence was the entrance of the United States into World War II. The US had previously been officially neutral and considered an isolationist country with its Neutrality Act but subsequently after the attack declared war on Japan the next day and entered the Pacific War. Then on December 11, 1941, four days after the Japanese attack, after the Italian declaration of war on the United States and the German declaration of war against the United States, which Hitler had orchestrated, the US was then at war with Germany and Italy. The US then became involved in the Battle of the Atlantic and the European theatre of war as well as with Japan.
Following the attack, the US interned 120,000 Japanese Americans, 11,000 German Americans, and 3,000 Italian Americans.