Soviet Foreign Policy, the Nazi-Soviet Pact, and the Great Patriotic War

The Communist International (Comintern) served as an instrument of Soviet foreign policy. In 1935 it adopted the "Popular Front" tactic in response to the advance of fascism across Europe, and the USSR backed the popular front governments of France and Spain during the decade. The Soviet Union joined the League of Nations in 1934 and intervened in the Spanish Civil War (1936-1939) through advisers, weapons, and the International Brigades, even as foreign communists inside the USSR itself faced repression and purges during the Great Terror. Tensions with Japan flared in the Far East, notably in the Khasan and Khalkhin Gol incidents of 1938-1939. Negotiations for a collective security alliance with France and Britain collapsed in 1939, amid mutual distrust between the USSR and the Western powers that deepened after the Munich Agreement of 1938, prompting a strategic pivot toward negotiation with Nazi Germany; Vyacheslav Molotov became Commissar for Foreign Affairs that same year.