The lend-lease program provided for military aid to any country whose defense was vital to the security of the United States. The plan thus gave Roosevelt the power to lend arms to Britain with the understanding that, after the war, America would be paid back in kind.
During World War II, the United States began to provide significant military supplies and other assistance to the Allies in September 1940, even though the United States did not enter the war until December 1941.
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