<P> The day after the attack , President Franklin D. Roosevelt addressed a joint session of the 77th United States Congress . Roosevelt called December 7 `` a date which will live in infamy '' . Congress declared war on the Empire of Japan amid outrage at the attack , the deaths of thousands of Americans , and the late delivery of the note from the Japanese government breaking off relations with the U.S. government . Pacifist Representative Jeannette Rankin , a Republican from Montana , cast the only dissenting vote . Roosevelt signed the declaration of war later the same day . Continuing to intensify its military mobilization , the U.S. government finished converting to a war economy , a process begun by provision of weapons and supplies to the Soviet Union and the British Empire . Japanese Americans from the West Coast were sent to internment camps for the duration of the war . </P>
what was the us reaction to pearl harbor
Congress declared war on the Empire of Japan