Perception in international relations has long been studied in political science, but historians have not paid suffi cient attention to it so far. Meanwhile, looking at known events through its prism allows us to draw new conclusions about their origins. The prehistory of World War II and its key episode — the failure of attempts to deter Hitler’s aggression in Europe through the joint eff orts of France and the Soviet Union — can serve as a fruitful field for testing this approach. For the military and political elites of France, the USSR was dangerous due to its unpredictability, but an internally fragile. This presumption leveled all the successes of the Soviet leadership in modernizing the country and the armed forces in the eyes of the French. The increased military danger in Europe after 1933 prompted Paris merely to offer Moscow the role of an ordinary participant in the system of collective security, which was based on the experience of World War I and designed as a new model for the development of international relations and minimization of conflicts between countries. The Soviet government viewed France as a leading imperialist power that prioritized anti-Soviet goals, but had a situational interest in limiting German expansion. At the same time, Moscow believed that Soviet-French cooperation could be effective only as an equal strategic alliance aimed at deterring a potential aggressor. This approach was rejected by French diplomacy, which followed the policy of appeasement. It was a source of a deep crisis in bilateral relations at the time of the 1938 Munich agreements. The collapse of appeasement in early 1939 led to a sharp turn by the French government to strategic planning for a possible war and created a window of opportunity for an agreement with the USSR. However, the inertia of old prejudices deprived the tripartite Anglo-French-Soviet negotiations in the spring and summer of 1939 of their practical content and opened the way for a Soviet-German agreement