Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (), was a policy under which the United States supplied the United Kingdom, the Soviet Union, France, China, and other Allied nations with food, oil, and materiel between 1941 and 1945. The aid was given free of charge on the basis that such help was essential for the defense of the United States.
The Lend-Lease Act was signed into law on March 11, 1941, and ended on September 20, 1945. A total of 50.1billion(equivalentto in ) worth of supplies was shipped, or 17% of the total war expenditures of the U.S. In all, 31.4billionwenttotheUnitedKingdom,11.3 billion to the Soviet Union, 3.2billiontoFrance,1.6 billion to China, and the remaining 2.6billiontootherAllies.Roosevelt′stopforeignpolicyadvisorHarryHopkinshadeffectivecontroloverLend−Lease,makingsureitwasinalignmentwithRoosevelt′sforeignpolicygoals.Materieldeliveredundertheactwassuppliedatnocost,tobeuseduntilreturnedordestroyed.Inpractice,mostequipmentwasdestroyed,althoughsomehardware(suchasships)wasreturnedafterthewar.SuppliesthatarrivedaftertheterminationdateweresoldtotheUnitedKingdomatalargediscountfor£1.075billion,usinglong−termloansfromtheUnitedStates,whichwerefinallyrepaidin2006.Similarly,theSovietUnionrepaid722 million in 1971, with the remainder of the debt written off.
Reverse Lend-Lease to the United States totalled 7.8billion.Ofthis,6.8 billion came from the British and the Commonwealth. Canada also aided the United Kingdom and other Allies with the Billion Dollar Gift and Mutual Aid totalling 3.4billioninsuppliesandservices(equivalentto61 billion in 2020) .
Lend-Lease effectively ended the United States' pretense of neutrality which had been enshrined in the Neutrality Acts of the 1930s. It was a decisive step away from non-interventionist policy and toward open support for the Allies.