Following the attack on Pearl Harbor, the American government felt the need to intern all individuals of Japanese ancestry or ethnicity under the cloak of national security. President Franklin Delano Roosevelt himself authorized this:
President Franklin Delano Roosevelt authorized the internment with Executive Order 9066, issued February 19, 1942, which allowed local military commanders to designate "military areas" as "exclusion zones," from which "any or all persons may be excluded." This power was used to declare that all people of Japanese ancestry were excluded from the entire Pacific coast, including all of California and most of Oregon and Washington, except for those in internment camps.
Roosevelt's Executive Order 9066 indicated many particular elements about how internment was to be handled and how Japanese individuals were to be treated by the U.S. Government. His order allowed the military to declare "exclusion zones" where citizen or non-citizen deemed to be a threat could be placed. In one of the first "enemy combatant" moves by the government, Roosevelt was able to embolden the executive branch and its extensions to ensure that anyone of Japanese or Korean ancestry be detained in these facilities. In doing so, Roosevelt was able to tap into public sentiment that targeted individuals whose ancestral nations were allied against the United States. In the process he was able to galvanize more public support for the aims of the war effort.