The Senate and House of Representatives approved the war declaration almost unanimously - the pacifist Congresswoman Jeannette Rankin of Montana became the first member of Congress to vote no on both the declaration of war on Germany during World War I and the declaration of war on Japan. Finally, at 4pm, Roosevelt signed the declaration of war on Japan.
Whereas the Imperial Government of Japan has committed unprovoked acts of war against the Government and the people of the United States of America:
Therefore be it Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the state of war between the United States and the Imperial Government of Japan which has thus been thrust upon the United States is hereby formally declared; and the President is hereby authorized and directed to employ the entire naval and military forces of the United States and the resources of the Government to carry on war against the Imperial Government of Japan; and, to bring the conflict to a successful termination, all of the resources of the country are hereby pledged by the Congress of the United States.
Approved, December 8, 1941, 4:10 p.m. E.S.T.»
Three days later, December 11, Japan's allies, Germany and Italy, both declared war on the United States. The U.S. Congress responded immediately by declaring war on them.