In the early hours of December 7, 1941 Japan launched a major surprise carrier-based air strike on Pearl Harbor without explicit warning, which crippled the U.S. Pacific Fleet, leaving eight American battleships out of action, 188 American aircraft destroyed, and over two thousand American citizens dead. From there they continued on to Guam, the Philippines, and Wake Island. The Americans, not yet officially involved in the war, were caught flat footed, giving Japan initial success though they were able to hold back the Imperial forces at Wake Island for almost a month.