Hand-in-hand with the promotion of Popular Fronts, Maxim Litvinov, the Soviet Commissar for Foreign Affairs between 1930 and 1939, aimed at closer alliances with Western governments, and placed ever greater emphasis on collective security. The new policy led to the Soviet Union joining the League of Nations in 1934 and the subsequent non-aggression pacts with France and Czechoslovakia. In the League the Soviets were active in demanding action against imperialist aggression, a particular danger to them after the 1931 Japanese invasion of Manchuria, which eventually resulted in the Soviet-Japanese Battle of Khalkhin Gol.