was a political doctrine of the Empire of Japan before World War II that stated that Manchuria and Siberia were Japan's sphere of interest and that the potential value to Japan for economic and territorial expansion in those areas was greater than elsewhere. Its supporters were sometimes called the Strike North Group.
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It was superseded by the diametrically-opposite rival policy, , which regarded Southeast Asia and the Pacific Islands as Japan's political and economic sphere of influence and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.
Origins
From the 1890s First Sino-Japanese War, Hokushin-ron came to dominate Japanese foreign policy. It guided both the Japanese invasion of Taiwan (1895) and the Japan–Korea Treaty of 1910, which annexed Korea to Japan. 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. A February 1907 Imperial National Defence guideline envisioned two strategies: Nanshu Hokushin Ron (南守北進, defence in the South and advance in the North) and Hokushu Nanshin Ron (北守南進, defence in the North and advance in the South). There was intense discourse within Japan on the two diverging theories. After World War I, Japanese troops were deployed as part of the Siberian Intervention during the Allied intervention in the Russian Civil War, with the hope that Japan could be freed from any future Russian threat by detaching Siberia and forming an independent buffer state. The Japanese troops remained until 1922, which encouraged discussion by Japanese strategic planners of the idea of permanent Japanese occupation of Siberia east of Lake Baikal.
Invasion of Manchuria
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. Insubordination by rogue Japanese military personnel in the Kwantung Army in 1931 led to the Mukden Incident and provided a pretext for the Japanese invasion of Manchuria. As the Kwantung Army had 12,000 men available for the invasion of Manchuria, it needed reinforcements. War Minister Sadao Araki was a solid supporter of the Hokushin-ron and of a proposed attack on the Soviet Far East and Siberia. He arranged for Chōsen Army forces to be moved from Korea north into Manchuria without permission from Tokyo in support of the Kwantung Army. 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. When the new cabinet was formed, Araki, as War Minister, was the real power in Japan. A puppet state was formed in Northeast China and Inner Mongolia, named Manchukuo, and was governed under a form of constitutional monarchy.
Factionalism within the military
Hokushin-ron was largely supported by the Imperial Japanese Army. General Kenkichi Ueda was a strong believer in the Hokushin-ron policy since he believed that Japan's main enemy was communism and that Japan's destiny lay in conquest of the natural resources of the sparely-populated Northern Asian mainland. General Yukio Kasahara was also a major proponent of the Hokushin-ron philosophy and felt strongly that the Soviet Union posed both a major threat and a major opportunity for Japan.
However, rival cliques of officers in the Army claimed to represent the "true will" of the Emperor. 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.