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 nearly $700 billion at 2007 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. It totaled $7.8 billion, of which $6.8 billion came from the British and the Commonwealth. Apart from that, there were no repayments of supplies that arrived before the termination date, the terms of the agreement providing for their return or destruction. (Supplies after that date were sold to Britain at a discount, for £1,075 million, 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. In sharp contrast to the American loans to the Allies in World War I, there were no provisions for postwar repayments. Some historians consider it an attempt to bolster Britain and the other allies as a buffer to forestall American involvement in the war against Nazi Germany.