neutral during World War II war materiel Allies Empire of Japan attack on Pearl Harbor Axis powers intern Europe first invaded occupied by Japan liberation Four Policemen relatively unscathed Philippines Japan Union Soviet Union World War II Britain World War I military
At first neutral during World War II, the United States began supplying war materiel to the Allies in March 1941. A total of $50.1 billion (equivalent to $719 billion in 2021) worth of supplies was shipped in 1941–1945, or 17% of the total war expenditures of the U.S. On December 7, 1941, the Empire of Japan launched a surprise attack on Pearl Harbor, prompting the United States to militarily join the Allies against the Axis powers, and in the following year, to intern about 120000 Japanese and Japanese Americans. The U.S. pursued a "Europe first" defense policy, with the Philippines being invaded and occupied by Japan until the country's liberation by the U.S.-led forces in 1944–1945. During the war, the United States was one of the "Four Policemen" who met to plan the postwar world, along with Britain, the Soviet Union, and China. The United States emerged relatively unscathed from the war, and with even greater economic and military influence.
