December 7, 1941: Japan attacks the American naval base at Pearl Harbor, Hawaii and also American military facilities in the Philippines, Guam, and Midway Island.

December 8, 1941: The United States declares war on Japan.

December 8, 1941: The Attorney General of the United States announces that the Federal Bureau of Investigation is detaining a select group of Japanese aliens who are regarded as “dangerous to the peace and security” of the nation. He states that only a small number of Japanese aliens would be arrested and warned against a tendency to consider all Japanese aliens in the United States as enemies. By December 11, 1941, 1200 Japanese aliens had been arrested.

December 8, 1941: The government closes the land borders of the United States to all enemy aliens and to all people of Japanese ancestry, whether alien or citizen.

December 11. 1941: The Army creates the Western Defense Command, which is given the responsibility of defending the Pacific Coast of the United States.

December 30, 1941: The Attorney General of the United States authorizes raids without a search warrant on the homes of people of Japanese descent provided that at least one resident is a Japanese alien.

December 1941 and following: Reports and rumors circulate regarding alleged sabotage by people of Japanese descent at Pearl Harbor and alleged Japanese submarine activity off the Pacific Coast.