The Americans were angry at the Japanese for their invasions of first Manchuria (1931), then China (1937), and later French Indochina (1940). After the Japanese moved into Indochina, President Roosevelt ordered a trade embargo on American scrap steel and oil, on which the Japanese military depended. But the American people felt that Asia was far away, and a large majority of voters did not want to go to war to stop Japan. The surprise attack on the Pacific fleet at Pearl Harbor on December 7, 1941 changed this, outraging the whole U.S. nation and convincing it that it must stop the Japanese army and navy.
