On December 7, 1941, the Japanese launched a surprise attack on the U.S. naval base at Pearl Harbor in Hawaii. The attack consisted of two waves of aircraft that inflicted heavy damage, sinking four U.S. battleships and damaging many other ships and aircraft. The attack killed over 2,400 Americans and drew the United States into World War II. The bombing of Pearl Harbor was planned by Japanese admirals as a preemptive strike to neutralize the U.S. Pacific fleet and enable Japan's military expansion across Asia and the Pacific.