As tensions grew between the U.S. and the. U.S.S.R, by the end of wwii, because of the separation of Germany, and wether Poland should choose their own government and Germany's reparations. (Reparations are compensation for war damage, so if another country has wronged another country, they'll most likely pay reparations in the form of money, or serious aid...) With that, the Soviets wanted to keep Germany a crippled nation became they wanted revenge for Germany invading them twice in the span of 30 years.