The attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service against the United States naval base at Pearl Harbor, Hawaii Territory, on the morning of December 7, 1941. The attack, also known as the Battle of Pearl Harbor, led to the United States' entry into World War II. The Japanese military leadership referred to the attack as the Hawaii Operation and Operation AI, and as Operation Z during its planning.
Japan intended the attack as a preventive action to keep the U.S. Pacific Fleet from interfering with its planned military actions in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States. Over the course of seven hours there were coordinated Japanese attacks on the U.S.-held Philippines, Guam and Wake Island and on the British Empire in Malaya, Singapore, and Hong Kong.
The attack commenced at 7:48 a.m. Hawaiian Time. The base was attacked by 353 Imperial Japanese aircraft in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged, with four sunk.