The article dwells to the changes at the international relations in Europe, caused by the Nazis coming to power, their military-diplomatic preparation and the beginning of World War II. In the context of the signing of Germany, Japan and Italy Anti-Comintern Pact main goal of Soviet diplomacy was “a policy of collective security”, based on the alliance with France and Czechoslovakia. However, Soviet efforts to prevent a new war in the bud, as the article shows, were unsuccessful because of the Anglo-French appeasement with respect to Germany's eastern neighbors (the Munich Agreement of 1938) and the sabotage of specific measures to combat Berlin (Anglo-Franco-Soviet negotiations in the summer of 1939). In such circumstances, according to the authors, the Soviet Union was forced to sign the Soviet-German non-aggression pact in 1939 and the secret protocol to it, as well as the neutrality pact with Japan in April 1941.