It's my understanding that the Germans, British, French, and Baltic peoples fought well to destroy the Soviet Union, while aid was given by the U.S.. Why did these combined forces not succeed?
You might be interested in the answer I wrote (using a former account, now deleted) to the question How come the Reds won the Russian civil war while the Whites had foreign support of Britain, France and USA? Although in later years the Soviets portrayed the Allied intervention as a capitalist plot to crush Bolshevism, in reality the Allied intervention was a half-hearted effort whose original goals had nothing to do with internal Russian politics.