At the Yalta Conference in February 1945 , Stalin was able to present his western allies , Franklin Roosevelt and Winston Churchill , with a '' fait accompli '' in Poland . His armed forces were in occupation of the country , and his agents , the communists , were in control of its administration . The USSR was in the process of incorporating the lands in eastern Poland which it had invaded and occupied between 1939 and 1941
Yalta Conference
Yalta Conference
Polish People's Republic