Stalin was concerned that the Western powers would force the creation of a single capitalist Germany, by joining their zones together and overpowering the East.
As a result, the first major crisis of the Cold War was over the future of Germany.
The USA, Britain and France knew that Germany would have to be supported economically if communism was to be resisted.
The allies wanted a strong, democratic Germany acting as a buffer against the communist states of Eastern Europe.
In contrast, Stalin wanted to: weaken Germany as a punishment for the war; help rebuild the USSR by stealing German industrial technology; make communism seem more attractive to the Germans.
These conflicting policies soon led to a crisis in international relations.