In November 1943 a conference of the Big Three (Joseph Stalin, Franklin Delano Roosevelt, Winston Churchill) was held in Tehran.

Among the matters that were agreed there was the division of influence in the Balkans and the incorporation into the USSR of Poland’s eastern territories, which had already been occupied as a result of Soviet aggression in 1939. The political division and shape of post-war Europe were ultimately confirmed during the Yalta Conference in February 1945. As a result of these agreements the countries of Central and Eastern Europe remained under the political influence of the USSR until the year 1989.