The
attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service on the American naval base at Pearl Harbor in Honolulu, Hawaii, the United States, just before 8:00
 a.m. on Sunday, December 7, 1941. At the time, the United States was a neutral country in World War II. The attack on Hawaii and other U.S. territories led the United States to formally enter World War II on the side of the Allies the day following the attack, on December 8, 1941. The Japanese military leadership referred to the attack as the
Hawaii Operation and
Operation AI, and as
Operation Z during its planning.