Soviet-Japanese border conflict

Soviet–Japanese border conflicts
Part of the interwar period
Khalkhin Gol, 1939. Soviet BT-7 tanks on the offensive.
Date 1932–1939 Location Mongolia, Primorsky Krai, Manchuria Result Soviet and Mongolian victory Soviet–Japanese Neutrality Pact
Belligerents
Union of Soviet Socialist Republics Mongolian People's Republic	Empire of Japan  Manchukuo
Commanders and leaders
Georgy Zhukov Grigory Shtern Vasili Blyukher Khorloogiin Choibalsan	Kenkichi Ueda Yoshijirō Umezu Michitaro Komatsubara
Casualties and losses
32,000 killed, wounded, or captured 350 tanks lost 140 armored cars lost 211 aircraft lost ~1,000 killed, wounded, or captured	20,000 killed, wounded, or captured 43 tanks lost several tankettes lost 162 aircraft lost ~3,000 killed, wounded, or captured

The Soviet–Japanese border conflicts (also known as 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 respective client states of Mongolia and Manchukuo. Lasting from 1932 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 conflicts were resolved in a series of engagements at Khalkin-Gol, where the Soviets and Mongolians 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.

Following the Japanese invasion of Manchuria in 1931, violations of the vaguely defined Manchukuo-Mongolia-USSR border were frequent. Most of these were misunderstandings, but some were intentional acts of espionage. According to the IJA, between 1932 and 1934, 152 border disputes occurred, largely because the Soviets found it necessary to gather intelligence inside Manchuria. For their part, the Soviets blamed the Japanese for 15 cases of border violation, 6 air intrusions, and 20 episodes of "spy smuggling" in 1933 alone. Hundreds more violations were reported by both sides throughout the following years. To make matters worse, Soviet-Japanese diplomacy and trust had declined even further in these years, with the Japanese being openly called "fascist enemies" at the Seventh Comintern Congress in July 1935.

In early 1935, the first shooting affray took place. From then until April 1939, the Imperial Japanese Army recorded 108 such incidents.

On 8 January 1935, the first armed clash, the Halhamiao incident (哈爾哈廟事件, Haruhabyō jiken), occurred on the border between Mongolia and Manchukuo. Several dozen Mongolian cavalry trespassed in Manchuria near some disputed fishing grounds, and engaged an 11-man Manchukuo army patrol unit near the Buddhist temple at Halhamiao, which was led by a Japanese military advisor. The Manchukuo Army incurred slight casualties, suffering 6 wounded and 2 dead, including the Japanese officer. The Mongols suffered no casualties, and withdrew when the Japanese sent a punitive expedition to reclaim the disputed area. Two motorized cavalry companies, a machine gun company, and a tankette platoon were sent and occupied the point for three weeks without resistance.

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