The attack on Pearl Harbor (or Hawaii Operation, as it was called by the Japanese Imperial General Headquarters)[6] was a surprise military strike conducted by the Japanese navy against the United States' naval base at Pearl Harbor, Hawaii, on the morning of Sunday, December 7, 1941, later resulting in the United States becoming militarily involved in World War II. It was intended as a preventive action to keep the U.S. Pacific Fleet from influencing the war Japan was planning to wage in Southeast Asia against Britain, the Netherlands, and the United States. The attack consisted of two aerial attack waves totaling 353[7] aircraft, launched from six Japanese aircraft carriers.