On March 11, 1941, FDR signed the Lend-Lease Bill. From the article:
"Lend-Lease Act
Proposed in late 1940 and passed in March 1941, the Lend-Lease Act was the principal means for providing U.S. military aid to foreign nations during World War II. It authorized the president to transfer arms or any other defense materials for which Congress appropriated money to “the government of any country whose defense the President deems vital to the defense of the United States.” By allowing the transfer of supplies without compensation to Britain, China, the Soviet Union and other countries, the act permitted the United States to support its war interests without being overextended in battle.
The Lend-Lease Act of March 11, 1941, was the principal means for providing U.S. military aid to foreign nations during World War II. The act authorized the president to transfer arms or any other defense materials for which Congress appropriated money to “the government of any country whose defense the President deems vital to the defense of the United States.” Britain, the Soviet Union, China, Brazil, and many other countries received weapons under this law.
By allowing the president to transfer war matériel to a beleaguered Britain–and without payment as required by the Neutrality Act of 1939–the act enabled the British to keep fighting until events led America into the conflict. It also skirted the thorny problems of war debts that had followed World War I.
Lend-Lease brought the United States one step closer to entry into the war. Isolationists, such as Republican senator Robert Taft, opposed it. Taft correctly noted that the bill would 'give the President power to carry on a kind of undeclared war all over the world, in which America would do everything except actually put soldiers in the front-line trenches where the fighting is.'"