The Battles of Khalkhyn Gol (; ; Japanese Romaji Nomon-Han Jiken; ; ) were the decisive engagements of the undeclared Soviet–Japanese border conflicts fought among the Soviet Union, Mongolia and the Empire of Japan in 1939. The conflict was named after the river Khalkhyn Gol, which passes through the battlefield. In Japan, the decisive battle of the conflict is known as the after a nearby village on the border between Mongolia and Manchuria. The battles resulted in the defeat of the Japanese Sixth Army.