Why did the potsdam conference further increase tensions between the united states and the soviet union

There were two, I think. They can be simply stated but the details were not easily handled. 
1. The defeat of Japan
2. How Germany and particularly Berlin was to be handled. It was agreed that it would be divided 4 ways: Russian, American, British and French. Japan was a particularly difficult problem. America did not want Russia to be in on Japanese defeat. It is one of the main reasons Truman used the Atomic Bomb.