The League of Nations was an organization formed by Britain, France, Japan and other imperialist powers after World War I for the re-division of the world through bargaining and temporary adjustments of conflicting interests. In 1931 the Japanese imperialists occupied China's Northeast and in 1933 Japan withdrew from the League of Nations in order to be able to extend her aggression more freely. In the same year the German fascists came to power, and later they, too, withdrew from the League of Nations to facilitate their preparations for a war of aggression. It was in 1934, when the threat of a fascist war of aggression was growing, that the Soviet Union joined the League of Nations; in this way the possibility arose of this imperialist organization for the re-division of the world being turned into one that might serve the cause of world peace. Italy withdrew from the League of Nations after her invasion of Abyssinia in 1935.
The Treaty of Mutual Assistance Between the Union of Soviet Socialist Republics and France and the Treaty of Mutual Assistance Between the Union of Soviet Socialist Republics and the Czechoslovak Republic were concluded in 1935.
The British bourgeois politician Lloyd George, who had been Prime Minister during World War I, declared in Parliament in November 1938 when Britain, France, Germany and Italy were going to negotiate, that peace could not be won by rejecting Soviet participation in the negotiations.
On September 1, 1939, the Germans invaded Poland and occupied most of her territory. On the 17th the reactionary Polish government fled abroad. On the same day, the Soviet Union dispatched its troops to eastern Poland in order to recover its own lost territories, emancipate the oppressed Ukrainian and Byelorussian peoples and check the eastward drive of the German fascist troops.
The Nomonhan truce agreement was concluded in Moscow in September 1939. In May 1939 the Japanese and the puppet "Manchukuo" troops had jointly attacked the troops of the Soviet Union and the People's Republic of Mongolia at Nomonhan, on the border between Mongolia and "Manchukuo", and were completely defeated by the Soviet and Mongolian forces in a heroic war of self-defence. The Japanese then sued for peace. The truce agreement provided for an immediate cease-fire and the formation of a commission of four, with two representatives from each side, to demarcate the frontier between the Mongolian People's Republic and the puppet state of "Manchukuo" at places where the conflict had taken place.
The Changkufeng truce agreement was concluded in Moscow on August 11, 1938. At the end of July and the beginning of August 1938, the Japanese had committed acts of provocation against the Soviet troops in the Changkufeng district on the border between China, Korea and the Soviet Union and had been vigorously repulsed. The Japanese sued for peace. The truce agreement provided for an immediate cease-fire and the formation of a commission of four, with two representatives from the Soviet side and two from the Japanese-"Manchukuo" side, to investigate the boundary lines and make a final settlement.