"It’s amazing how quickly our Russian allies turned into our Cold War enemies at the end of WWII."
The 'our Russian allies' part sounds a bit strange. Are you aware that the Soviet Union started the war on the Hitler side? What's amazing is that in modern Russia most people don't believe it.
Germany invaded Russia in June 1941. The US entered the war in December 1941. From the US perspective, the Russians were never anything but allies in the war.