In December 1941, the Imperial Japan attacked Pearl Harbor in Hawaii. Shortly afterwards in February 1942, President Franklin Roosevelt signed Executive Order 9066. The order forced approximately 120,000 Americans of Japanese descent ("Nisei") and Japanese-born residents ("Issei") in California, Oregon, Washington, and Alaska on the West Coast of the United States to leave their homes. About 5,000 left the off-limits area during the "voluntary evacuation" period, and avoided internment. The remaining 110,000 were soon removed from their homes by Army and National Guard troops.