Japan's alliance with Nazi Germany and Fascist Italy in 1940 focused world attention on the Asian nation's military power and imperial ambition. The Japanese attack on Pearl Harbor on December 7, 1941 plunged the United States into war and planted the notion of Japanese treachery in the minds of Americans. The hysteria that enveloped the West Coast during the early months of the war, combined with long standing anti-Asian prejudices, set the stage for what was to come.

For both Japan and America, World War II had all of the ugly overtones of racial conflict. Although America was also at war with Germany and Italy, government officials did not recommend that German and Italian resident aliens (or American citizens of German or Italian ancestry) be rounded up as a group and confined for the duration of the war. While German or Italian enemies were often viewed as misguided victims of despotic leaders, Japanese people were referred to as "yellow vermin," "mad dogs," and "monkey men." Racist wartime propaganda further exacerbated fears of invasion and prejudice against people of Japanese decent.

Akiko K.: No Longer an Equal American (oral history transcript)

Members of the War Department argued for removal of the Issei and their Nisei children from areas regarded as vital to national security. National officials were influenced by politicians from West Coast districts, where opposition to Japanese Americans ran high.

"Their racial characteristics are such that we cannot understand or trust even the citizen Japanese." — Henry L. Stimson, Secretary of War, 1942

"I'm for catching every Japanese in America, Alaska, and Hawaii now and putting them in concentration camps....Damn them! Let's get rid of them now!" — Congressman John Rankin, Congressional Record, December 15, 1941

On the evening of December 7, 1941, FBI agents, and local and military police took 736 Japanese aliens into custody. By December 11, the number had grown to 1,370. This group included persons believed most likely to be spies or saboteurs: Shinto and Buddhist priests, newspapermen, community leaders, Japanese language teachers, and subscribers to suspect publications. Enemy Alien Hearing Boards were established to judge the loyalty of these individuals. All remained in detention during the slow course of the hearing process.