Executive Order 9066, promulgated on February 19, 1942, was the first and most important document in a series of military and government directives in the aftermath of the Japanese attack on the United States Pacific Fleet at Pearl Harbor, Hawaii, on December 7, 1941. That order from President Franklin D. Roosevelt led directly to the incarceration of 120,000 men, women, and children of Japanese ancestry residing in four western states in the spring of 1942. The order authorized the secretary of war to establish military zones on the West Coast from which enemy aliens could be removed as security risks—a label that was soon applied to the entire Japanese population residing on the West Coast.