The Soviet–Japanese border conflicts (also known was the Soviet-Japanese Border War) was a series of battles and skirmishes between the forces of the Union of Soviet Socialist Republics and the Empire of Japan, as well as their puppet states of Mongolia and Manchukuo. Lasting from 1935 to 1939, most of the conflicts were small border skirmishes until May 1939, with the notable exception of the Battle of Lake Khasan. The Border War was resolved in a series of engagements at Khalkin-Gol, where the Soviets inflicted a decisive defeat on the Japanese. This resulted in the Soviet-Japanese Neutrality Pact. It should not be confused with the conflict in August 1945 when the Soviet Union declared war in support of the other Allies of World War II and launched the Manchurian Strategic Offensive Operation.