Before World War II, Guam was one of five American jurisdictions in the Pacific Ocean, along with Wake Island in Micronesia, American Samoa and Hawaii in Polynesia, and the Philippines. On December 8, 1941, hours after the attack on Pearl Harbor, Guam was captured by the Japanese, who occupied the island for two and a half years. During the occupation, Guamanians were subjected to forced labor, incarceration, torture and execution. American forces recaptured the island on July 21, 1944, which is commemorated as Liberation Day. Since the 1960s, Guam's economy has been supported primarily by tourism and the U.S. military, for which Guam is a major strategic asset.