Hokushin-ron

It enjoyed wide support within the Imperial Japanese Army during the interwar period but was abandoned in 1939 after military defeat on the Mongolian front at the Battles of Khalkhin Gol (known in Japan as the Nomonhan incident) and the signing of Soviet–Japanese Neutrality Pact in 1941.

It was superseded by the diametrically-opposite rival policy, Nanshin-ron (南進論, "Southern Expansion Doctrine" or "Southern Road"), which regarded Southeast Asia and the Pacific Islands as Japan's political and economic sphere of influence and aimed to acquire the resources of European colonies and to neutralize the threat of Western military forces in the Pacific.

[1] After the Russo-Japanese War (1904-1905) Field Marshal Prince Yamagata Aritomo, a political and military ideological architect of Hokushin-ron, traced the lines of a defensive strategy against Russia.

[1] An essential step in the Hokushin-ron proposal was for Japan to seize control of Manchuria to obtain an extensive de facto land border with the Soviet Union.

The plot to seize Manchuria proceeded as planned, and when presented by the fait accompli, all that Prime Minister Reijirō Wakatsuki could do was weakly protest and resign with his cabinet.

The radical ultranationalist Imperial Way Faction (Kōdōha) had many young activists who were strongly supportive of the Hokushin-ron strategy and a preemptive strike against the Soviet Union.

They were opposed by the more moderate conservative Control Faction (Tōseiha), which favored a more cautious defence expansion and sought to impose greater discipline over the Army and war with China as a strategic imperative.

[4] Relations between the Japanese Army and Navy were never cordial and were often marked by deep hostility, a situation whose origin can be traced back to the Meiji period.

[6] The Kōdōha faction, which favoured Hokushin-ron, was dominant in the Army during Araki's tenure as Minister of War from 1931 to 1934 and occupied most significant staff positions.

The Imperial Defence Plan, formulated in June 1936, incorporated a balance of both Hokushin-ron and Nanshin-ron by requiring both the Army and the Navy to take a peaceful and unprovocative approach to their "enemies".

Aggressive actions initiated by Japanese staff and field officers on the Soviet border with Manchukuo and Mongolia led to the disastrous Battles of Khalkhin Gol (1939), which resulted in heavy casualties for Kwantung Army and severely challenged its much-vaunted reputation.