Hindsight is always 20/20.
There are those who say that providing Lend Lease to the Soviets after Hitler invaded Russia was the worst thing we could have done, that it would have been preferable to let the Nazis and the Communists devour each other somewhere between Leningrad and Vladivostok.
Moscow’s Communist subversion of the West and their obtaining America’s atomic technology via the Rosenbergs, which enabled the Soviets’ post-War aggression would seem to validate the view that aiding them was a strategic mistake.
Quite frankly, if Communism had collapsed in the old Soviet Union following the Nazi invasion of 1941, it becomes questionable if Mao tse Tung would have risen to power in China, which would have resulted in no Communist puppet regimes in Korea OR Vietnam. Without aid from the West, Stalin would have been hanging from a lamp post, he was at best one of the stupidest (although violent) individuals to ever lead a nation. (example: even in the hours prior to the German invasion of Russia, Stalin directed that train loads of iron ore and other minerals continue to be shipped to German as part of the Molotov-Ribbentrop agreement, despite hard evidence that an invasion was imminent)
A reasonable student of history would conclude that Communism was the baby rattlesnake in the baby’s crib. The failure to kill the little rattler resulted in untold global tragedy.