Eighty years ago, this month, Soviet and Japanese forces clashed on an obscure river along the border between Mongolia and Manchuria (Manchukuo) called Khalkhin Gol. The battle was the climax of a six-year-long conflict between Japan and the Soviet Union.
The Soviet-Japanese war, 1932-1939, gets scant mention in accounts of World War II. Yet it had a profound effect on Japan’s strategic doctrine and paved the way for Tokyo’s decision to attack Great Britain and the United States.
Had Japan continued prosecuting its war with the Soviet Union, the war in the Pacific would have taken a dramatically different turn. Indeed, it probably would never have happened.
Japanese Strategic Doctrine, 1890-1945
Ever since Japan emerged as an East Asian power in the late 19th century, its strategic doctrine revolved around two contesting views. One group, mostly centered around the Japanese Imperial Army, proposed a Northern Expansion Doctrine or Northern Road (Hokushin-ron). A second group, mostly based in the Imperial Navy, advocated for a Southern Expansion Doctrine or Southern Road (Nanshin-ron).
The Northern Road group believed that Manchuria and Siberia should be the focus of Japan’s imperial ambitions and that Russia, and later the Soviet Union, was Japan’s greatest threat. The Southern Road Group believed that southeast Asia and the Pacific Islands should be the focus of Japanese expansion and that the United States was Japan’s principal enemy.
Significantly, the Northern Road was the initial focus of Japanese imperialism. Between 1890 and 1939, Japan fought two wars with China (1890, 1931); fought and defeated Czarist Russia in the Russo-Japanese War (1904); invaded and seized German colonies in China and the North Pacific (1914); and participated in the Allied intervention in Siberia during the Russian Civil War (1918).
In the process, it took possession of the Korean peninsula; Taiwan; Tsingtao; the Mariana, Caroline and Marshall Islands; and Manchuria. During the Russian Civil War, Tokyo even considered seizing all of eastern Siberia, east of Lake Baikal. During this period, Japanese strategic doctrine called for “defense in the south and advance in the north.” To that end, Tokyo aligned itself diplomatically with Great Britain and, to a lesser extent, the U.S.
The Imperial Defense Plan of 1936, the genesis of Japan’s “Greater East Asia Co-Prosperity Sphere,” tried to reconcile the conflicting doctrines by proposing to seize the natural resources of Siberia by attacking the Soviet Union via Manchuria, while also targeting the resource-rich colonies of the Dutch, British and French in southeast Asia, especially the petroleum fields of the Dutch East Indies (Indonesia).
The Japanese seizure of Manchuria, a region where Czarist Russia once had wide-ranging interests, led to growing tensions between Tokyo and Moscow. The Sino-Japanese war, an undeclared conflict, lasted from 1932 through 1939, and came to a dramatic climax at the Battle of Khalkhin Gol.
The Soviet-Japanese War, 1932-1939
Disputes over the demarcation of the border between Manchuria and Mongolia were the initial cause of the conflict. Japan believed the border ran along the Khalk river (Khalkhin Gol in Mongolian). The Soviets and the Mongols believed the border was 10 miles further east, at the village of Nomonhan. Between 1932 and 1939, both sides accused the other of hundreds of border incursions. The Soviets were also concerned that Japanese troops in Manchuria were within easy striking distance of the Trans-Siberian Railroad, its only reliable link to the Soviet Far East.
Starting in 1935, the cold war between Japan and the Soviet Union began to heat up dramatically. Between 1935 and 1939, there were a total of 108 incidents when both sides exchanged gunfire. Both parties steadily built up their military forces in the area, while relations between the two countries steadily worsened.
In July 1935, the Seventh Comintern Congress declared Japan to be a “fascist enemy” of the Soviet Union. The next year, in 1936, Japan and Nazi Germany signed the anti-Comintern pact, in which they agreed to consult on how to respond to “safeguard their common interests” should either be attacked by the USSR.
After Japan invaded China in July 1937, the USSR supplied the Chinese government with ammunition, military equipment and supplies, including 82 tanks; 1,300 pieces of artillery; 65,000 rifles and machine guns; 225 aircraft; and more than 1,500 trucks and tractors. Between 1937 and 1941, only the Soviet government provided substantial military aid to Chiang Kai-shek’s forces.
Moscow also provided 3,665 military advisers and volunteers as part of the Soviet Volunteer Group, along with loans totaling $250 million. By 1941, more than 1,200 planes had been sent to China. Roughly half the planes were flown by Soviet pilots, ostensibly volunteers, wearing Chinese military uniforms.
When the Soviet aid began, the Chinese air force consisted of 100 antiquated planes and were outnumbered 13 to 1 by the better trained and equipped Japanese.
Soviet volunteers conducted the only Chinese air raid of Japanese territory, on Feb. 23, 1938, when they attacked the main base of the Japanese air force on Taiwan. Between 1937 and 1941, Soviet pilots shot down 625 Japanese aircraft. The Soviet volunteer squadrons were withdrawn in 1941 when Japan and the Soviet Union signed a nonaggression pact. In desperation, China turned to the United States. The Roosevelt administration promptly authorized the creation of the First American Volunteer Group, known as the Flying Tigers.
The Battle of Khalkhin Gol
Japanese-Soviet hostilities reached a climax between May and September 1939, in the Battle of Khalkhin Gol on the Mongolian-Manchurian frontier. The conflict began with a series of border skirmishes in May and June and would ultimately involve more than one hundred thousand men.
The battle occurred at a time when Europe was moving inexorably toward war amid a flurry of diplomatic activity between the British and French governments, Nazi Germany and the Soviet Union. Both the British and French governments, on the one hand, and the Soviets, on the other, were looking to negotiate a nonaggression pact with Germany. On Aug. 23, 1939, the world was stunned by the announcement of the Molotov-Ribbentrop Pact, a nonaggression treaty between Germany and the Soviet Union.
As Stalin was negotiating the details of the German-Soviet Pact, he was also pouring additional troops into eastern Mongolia. In 1938, a 42-year-old corps commander who had distinguished himself during the Russian Civil War named Georgy Zhukov had been put in command of the First Soviet Mongolian Army Group.
By the summer of 1939, Japanese strength was estimated at around 80,000 soldiers, 180 tanks and 450 aircraft. Soviet strength had reached approximately 50,000 soldiers, supported by 498 tanks and armored vehicles and 581 fighters and bombers.
In July 1939, Japanese forces moved across the frontier with Mongolia and, inflicting heavy losses on Soviet and Mongolian troops, occupied the disputed border region.
On Aug. 20, 1939, upon the signing of the German-Soviet Nonaggression Pact, Zhukov launched an attack on Japanese forces in Mongolia. Using his artillery and infantry to pin Japanese forces in place, Zhukov sent his tanks to attack on both flanks of the Japanese position. The attack encircled the Japanese Sixth Army and ultimately crushed it. Roughly 75 percent of the Japanese frontline troops were killed in action. The fighting ended on Sept. 16.
The next day, Soviet troops invaded Poland.
The Soviet military and diplomatic offensive stunned Japan. The conflict was occurring on the heels of the Great Purge, carried out between 1936 and 1938, which had decimated much of the senior leadership of the Soviet military. The Japanese consequently had a low opinion of Soviet commanders. The nonaggression pact left Japan diplomatically isolated from its German ally. Faced with the prospect of dealing with the Soviet Union on its own, Japan moved quickly to de-escalate the conflict.
The Battle of Khalkhin Gol was the largest tank battle hitherto fought. Zhukov’s battle tactics and his use of armor at Khalkhin Gol presaged the blitzkrieg tactics that the Wehrmacht unleashed in Poland. For his success, Zhukov was declared a Hero of the Soviet Union, the first of four. The next year, he was made a general in the Soviet Army.
The defeat at Khalkhin Gol discredited the proponents of the Northern Road Strategy in the Japanese Imperial Army and tipped the balance to the proponents of the Southern Road Strategy and the Imperial Japanese Navy.
Aftermath: The Soviet-Japanese Nonaggression Pact of 1941
On April 13, 1941, Japan and the Soviet Union signed a nonaggression pact. They also agreed to respect the territorial integrity of Mongolia and Manchukuo (Manchuria). At the time the agreement was signed, Japan was certainly aware that Germany was preparing to invade the Soviet Union. By signing the pact, Japan was able to ensure that the Soviet Union would not threaten Manchukuo, freeing itself to pursue the Southern Road Strategy.
When German forces invaded the Soviet Union on June 22, 1941, Tokyo opted not to renew hostilities with the USSR, despite Berlin’s urging to invade. Instead, three months later, Japanese forces invaded French Indochina.
The Roosevelt administration responded by placing an embargo on exports of scrap iron and petroleum, among other things, to Japan. Deprived of critical raw materials, Tokyo set in motion plans to seize European colonies in Southeast Asia and to strike against the one force it believed could stymie Japanese ambitions: the U.S. Navy.
Japan did keep its options open, especially in light of German’s initial successes on the Eastern Front. In July 1942, Gen. Tomoyuki Yamashita, the Tiger of Malaya, was dispatched to Manchuria, ostensibly to organize Japanese troops there for a potential invasion of Siberia. By then, however, Japan was irrevocably committed to the Southern Road Strategy.
Had the Japanese been victorious at Midway and had the German 6th Army succeeded in taking Stalingrad, it’s possible that Japan might have invaded Siberia.
Japan’s decision not to invade the Soviet Union allowed Stalin to transfer 18 divisions, 1,700 tanks and 1,500 aircraft — some of which included the veterans of Khalkhin Gol — to the Eastern Front during the critical Battle of Moscow in December 1941.
Zhukov’s Siberian divisions helped turn the tide, stopping the German advance within sight of Moscow, and participated in the subsequent Soviet counterattack. It’s unlikely that the Soviet Union could have withstood a two-front war against both Germany and Japan in 1941.
Had Japan opted to venture north instead of looking south, it’s also likely that the U.S. would have continued to supply Japan with the critical war materials, especially scrap iron and petroleum, on which Japan was dependent.
In the end, the most likely alternative history of the Pacific war is not one in which Japan emerged victorious, but one in which a Pacific War was never fought. Had Japan opted to follow the Northern Road Strategy, the history of WWII and America’s role in it would have taken a very different trajectory.