The Lend-Lease program achieved a significant contribution to the Allied war effort during World War II by providing military aid and supplies to countries fighting against the Axis powers, mainly the United Kingdom, China, and later the Soviet Union. Initiated in 1941, the program allowed the U.S. to supply weapons, vehicles, food, and other resources without immediate payment, which bolstered the military capacity of the Allies while keeping the U.S. economy active. By fostering alliances and enhancing logistical support, Lend-Lease played a pivotal role in sustaining the Allies until the U.S. formally entered the war after the attack on Pearl Harbor in December 1941.