The Problems where that the soviet and nazi where both radical and andawful countries. But the soviets weren't the ones trying to takeover the world , since germany in 1941 invaded. soviet union joined the allies. After WWII and especially after the united states dropped the nuclear bombs in japan which made the soviet union interested in creating their own nuclear weapons which they did. Since the soviets and the us had nuclear weapons their political views where hostile towards each other but post WWII europe. Hope This Helps?
