Nanshin-ron

The Southern Expansion Doctrine (南進論, Nanshin-ron^?) was a political doctrine in the Empire of Japan which stated that Southeast Asia and the Pacific Islands were Japan's sphere of interest and that the potential value to the Japanese Empire for economic and territorial expansion in those areas was greater than elsewhere.

This political doctrine was diametrically opposite that of the "Northern Expansion Doctrine" (北進論, Hokushin-ron^?) largely supported by the Imperial Japanese Army, which stated the same except with regards to Manchuria and Siberia. After the military setbacks at Nomonhan on Mongolian front, the Second Sino-Japanese War, and negative Western attitudes towards Japanese expansionist tendencies, Southern Expansion Doctrine superseded to procure colonial resources in South East Asia and neutralize the threat posed by Western military forces in the Pacific. The Army favored a "counterclockwise strike" while the Navy favored a "clockwise strike".

The “Southern Expansion Doctrine” was initially vaguely defined. It possibly originated during the final years of the Edo period, when the leaders of the Meiji Restoration determined that Japan needed to pursue a course of imperialism in emulation of the European nations in order to attain equality in status with the west. As the European powers were laying claim to territories ever closer to the Japanese home islands, the “Southern Expansion Doctrine” occupied an increasingly important place in Japanese policy and diplomacy from the early Meiji period.

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Wikipedia