Nanshin-ron

Its focus was to procure resources from European Southeast Asian colonies, eliminate supply routes to China, and neutralize the Allied military presence in the Pacific.

[3] During the early Meiji period, Japan derived economic benefits from Japanese emigrants to Southeast Asia, among which there were prostitutes (Karayuki-san)[4] who worked in brothels in British Malaya,[5] Singapore,[6] the Philippines,[7] the Dutch East Indies[8] and French Indochina.

[10] The formal annexation and incorporation of the Bonin Islands and Taiwan into the Japanese Empire can be viewed as first steps in implementation of the "Southern Expansion Doctrine" in concrete terms.

The focus of the "Southern Expansion Doctrine" expanded to include the island groups (the South Seas Mandate), whose economic and military development came to be viewed as essential to Japan's security.

Meiji-period nationalistic researchers and writers pointed to Japan's relations with the Pacific region from the 17th-century red seal ship trading voyages, and Japanese immigration and settlement in Nihonmachi during the period before the Tokugawa shogunate's national seclusion policies.

The success of the Navy in the economic development of Taiwan and the South Seas Mandate through alliances among military officers, bureaucrats, capitalists, and right-wing and left-wing intellectuals contrasted sharply with Army failures in the Chinese mainland.

The Washington Naval Treaty had restricted the size of the Japanese Navy and also stipulated that new military bases and fortifications could not be established in overseas territories or colonies.

To evade monitoring by the Western powers, they were camouflaged as places to dry fishing nets or coconut, rice, or sugar-cane farms, and Nan'yō Kohatsu Kaisha (South Seas Development Company) in co-operation with the Japanese Navy, assumed responsibility for construction.

In 1931, the "Five Ministers Meeting" defined the Japanese objective of extending its influence in the Pacific but excluded areas such as the Philippines, the Dutch East Indies and Java, which might provoke other countries.

[16] The doctrine also formed part of the basis of the Greater East Asian Co-Prosperity Sphere, which was proclaimed by Japanese Prime Minister Konoe Fumimaro from July 1940.

In September 1940, Japan occupied northern French Indochina, and in November, the Pacific Islands Bureau (Nan'yō Kyoku) was established by the Foreign Ministry.