Lend-Lease (Public Law 77-11) was the name of the program under which the United States of America supplied the United Kingdom, the Soviet Union, China, France and other Allied nations with vast amounts of war material between 1941 and 1945 in return for, in the case of Britain, military bases in Newfoundland, Bermuda, and the British West Indies. It began in March 1941, over 18 months after the outbreak of the war in September 1939. It was called An Act Further to Promote the Defense of the United States. This act also ended the pretense of the neutrality of the United States. Hitler recognized this and consequently had his submarines attack US ships such as the SS Robin Moor, an unarmed merchant steamship destroyed by a German U-boat? on 21 May, 1941 outside of the war zone.
A total of $50.1 billion (equivalent to $759 billion at 2008 prices) worth of supplies were shipped: $31.4 billion to Britain, $11.3 billion to the Soviet Union, $3.2 billion to France and $1.6 billion to China. Reverse Lend Lease comprised services (like rent on air bases) that went to the U.S. totaled $7.8 billion, of which $6.8 billion came from the British and the Commonwealth. The terms of the agreement provided that the material was to be used until time for their return or destruction. (Supplies after the termination date were sold to Britain at a discount, for £1.075 billion, using long-term loans from the U.S.) Canada operated a similar program that sent $4.7 billion in supplies to Britain and Soviet Union.
This program is seen as a decisive step away from American non-interventionism since the end of World War I and towards international involvement. The Americans demanded that this rent be settled, and it took until 2006 for the UK government to settle its debt to the USA.