Potsdam and relations between the West and the USSR

A. What was decided at the Potsdam conference?
The allied leaders arranged for July 1945 in the Berlin suburb of Potsdam, a conference. There weren’t taken any decision, due to the fact the distrust between Stalin and Truman, so they had different disagreements, over what to do with Germany, over reparations and also over Soviet policy in Eastern Europe.

B. Why did the wartime unity of the Allies break down between 1945 and 1947?
The wartime unity of the Allies broke down because there was tension and suspicion between the USA’s president, Truman, and the USSR leader, Stalin. Because of these, in the Potsdam Conference, they did not come to an agreement in some major aspects: what to do with Germany, reparations and Soviet policy in eastern Europe.
Furthermore, in the months after the Potsdam Conference Stalin achieved the control of eastern Europe. Poland, Hungary, Romania Bulgaria and Albania had all Communist governments that were loyal to Stalin. Churchill described the borders between them and the West as an “iron curtain”. With Communist governments in all eastern Europe, Stalin tightened his control, eliminating opposition. In 1947, he set up the Cominform to organize and control all the Communist Parties, replacing independent leaders with people who were loyal to him.

C. "The Truman Doctrine generated much more tension than the Berlin Blockade" How far is that statement true?
Different things increased the Cold War tension, such as the Truman Doctrine: giving money to countries that were going to turn into Communism, to stop that movement. Or the Berlin Blockade, with USSR taking control of Germany. But what event produced more tension?
On the one hand, the Truman Doctrine added tension to the Cold War because USA was sending equipment and advice to any country which was, in the American view, threatened by a Communist takeover. They did this as a way of containing Communism.
On the other hand, the Berlin Blockade added much more tension to the Cold War, because as people living in the Soviet zone wanted to leave that zone, and Stalin, who had the control of Germany´s capital, closed all the railways and any possible way of going away from that zone, and that hurted a lot of countries and people.
To conclude, I think the Berlin Blockade added more tension to the Cold War that the Truman Doctrine because that involved more countries.