Although the rapid industrialization the Soviet Union experienced in the 1930s had the potential to enable the Soviet Air Forces to be effective against the Luftwaffe, Stalin's purges left the organization weakened. However, when Germany invaded in June 1941, the size of the Soviet Air Forces allowed it to absorb horrendous casualties and still maintain capability. Despite the near collapse of Soviet forces in 1941, they survived, as German forces outran their supply lines and the Americans and British provided Lend Lease assistance.