Mongolia in World War II

Outer Mongolia — officially the Mongolian People's Republic — was ruled (1930s to 1952) by the communist government of Khorloogiin Choibalsan during the period of World War II and had close links with the Soviet Union.

[4] These agreements were directed at Japan, which had occupied Manchuria and advanced into Inner Mongolia,[2] and had as their object the protection of the Soviet Trans-Siberian Railway.

[3] On 13 August 1937, as part of their effort to support China in its war with Japan, the Soviets decided to station troops along Mongolia's southern and southeastern frontiers.

[5] In his address to the Third Session of the Supreme Soviet on 31 May 1939, Foreign Commissar Vyacheslav Molotov declared that "we shall defend the frontiers of the Mongolian People's Republic just as resolutely as our own border.

"[4] Mongolia was heavily involved in the Soviet–Japanese border conflicts, most notably the four-month-long Battles of Khalkhin Gol (May–September 1939).