Famous Soviet historian examines the Stalinist concept of foreign policy of the USSR in 1939-1941, its implementation and concrete results. Based on previously unknown and little-studied sources, he gives new assessments of such historical facts as the conclusion of the Soviet-German non-aggression treaty and the signing of secret protocols, events in Poland, the Baltic states and Bessarabia, the Soviet-Finnish war, Molotov's negotiations with Hitler in November 1940 in Berlin, crime in Katyn, etc.