In 1945, the Big Three held two conferences – at Yalta (February) and Potsdam (July) – to try to sort out how they would organise the world after the war.   It was at these conferences that the tensions between the two sides became obvious.
     
Yalta (February 1945)

Held during the war, on the surface, the Yalta conference seemed successful.   The Allies agreed on a Protocol of Proceedings.  The decisions included:    

1	A decision that Russia would join the United Nations.
2	A decision that Germany would be divided into four ‘zones’, which Britain, France, the USA and the USSR would occupy after the war.
3	A decision that Nazi war-criminals would be brought to trial.
4	A decision that a Polish Provisional Government of National Unity would be set up 'pledged to the holding of free and unfettered elections as soon as possible'.
5	A decision to help the freed peoples of Europe set up democratic and self-governing countries by helping them to (a) maintain law and order; (b) carry out emergency relief measures; (c) set up governments; and (d) hold elections (this was called the 'Declaration of Liberated Europe').
6	A decision to set up a commission to look into reparations.

 Potsdam (July 1945)  

At Potsdam, the Allies met after the surrender of Germany (in May 1945) to decide the post-war peace – Potsdam was the Versailles of World War II.
    
America had a new president, Truman, who was determined to ‘get tough’ with the Russians.   Also, when he went to the Conference, Truman had just learned that America had tested the first atomic bomb.   It gave the Americans a huge military advantage over everyone else, but Truman did not tell Stalin - something that angered Stalin when the Americans used the atomic bomb at Hiroshima. On the other hand, in March 1945, Stalin had invited the non-Communist Polish leaders to meet him, and arrested them.  So, at Potsdam, the arguments came out into the open.  The Conference agreed the following Protocols:

1	A decision to set up the four ‘zones of occupation’ in Germany.   The Nazi Party, government and laws were to be destroyed, and 'German education shall be so controlled as completely to eliminate Nazi and militarist doctrines and to make possible the successful development of democratic ideas.
2	A decision to bring Nazi war-criminals to trial.
3	A decision to recognize the Polish Provisional Government of National Unity and hold 'free and unfettered elections as soon as possible'.
4	Russia was allowed to take reparations from the Soviet Zone, and also 10% of the industrial equipment of the western zones as reparations.   America and Britain could take reparations from their zones if they wished.

Truman presented this as a compromise but in fact the Allies had disagreed openly about:  
1.   the details of how to divide Germany.
2.   the size of reparations Germany ought to pay.
3.   Russian influence over the countries of Eastern Europe.