Following Germany's invasion of the USSR in June 1941, the United Kingdom and the Soviet Union became allies. Although a neutral nation, Reza Shah Pahlavi had brought Iran closer to Germany. This concerned the British who feared that the Abadan Oil Refinery, owned by the Anglo-Iranian Oil Company, might fall into German hands — the refinery produced eight million tons of oil in 1940 and was thus a crucial part of the Allied war effort. For the Soviets, Iran was a country of extreme strategic importance. The German "Wehrmacht" was steadily advancing through the Soviet Union and there were few ways for the Allies to get desperately needed American Lend-Lease supplies to the Soviets.