 In 1939 , following the 1938 Munich Agreement and Hitler 's subsequent invasion of Czechoslovakia , Stalin believed that Britain and France would not be reliable allies against German expansion so instead sought to conciliate Nazi Germany . In May 1939 Maxim Litvinov , the People 's Commissar for Foreign Affairs , was dismissed ; Molotov was appointed to succeed him . Molotov was succeeded in his post as Premier by Stalin . 
