The article is dedicated to the 110th anniversary of the birth of Andrei Andreevich Gromyko, the Soviet foreign minister in 1957-1985, who started his diplomatic career in 1939. In the focus of the study is the ongoing deterioration in the sphere of strategic stability and arms control, escalation of tensions in the current international relations. The author explores the experience of the détente period in the 1970s de facto leading to the temporary end of the Cold War and reasons for its resumption. Principles and methods of the Soviet diplomacy are analyzed; its key features are defined: balance of interests, principles and pragmatism; equal levels of security; strategic parity, reciprocity, realism, the view of diplomacy as science and art. The article provides the historical context of the Helsinki Process and shows that the USSR’s foreign policy pursued the idea of a new quality of international relations, including the category of trust. This approach envisaged that the détente was leading to close cooperation with the West within a new modus vivendi, a new system of checks and balances while not eliminating antagonism between two different political and socioeconomic philosophies of the world development. On this basis the notion of peaceful coexistence between socialism and capitalism was not considered to be an obstacle for international relations to acquire new quality, which was to consign the Cold War to the past. The conclusion is drawn that the Soviet leadership treated the détente as an end of the Cold War and as a new period of relations between the USSR and the West, based on mutual compromises and understanding.