Because the invasion of China was an unexpected development, initiated in 1931 by Japan’s expeditionary forces in north China, the central Government, although supporting the military’s move, could devise only ad hoc explanations, justifying events as they occurred. The first to publish a general justification were non-government rightist ideologues, who worked closely with the younger military officers who were in charge of the operation. It was only nine years after the Manchurian Incident took place, when the whole series of events was a fait accompli, that the Government was able to present an ideological rationale. This took the form of a proclamation by Matsuoka Yōsuke (1880-1946), then Minister for Foreign Affairs in the Konoye Cabinet, on 2 August 1940.31
The range of the Greater East Asia Co-Prosperity Sphere had been determined by military necessity. There had been a series of position papers drawn up by the staff officers of the Navy and the Army, in cooperation with scholars, to defend the gains made by the military after 1931. The fountainhead of all these strategic experiments was the idea of an East Asian federation. This notion was conceived by Ishiwara Kanji (1889-1949), one of the staff officers of the expeditionary force responsible for the military action during and after the Manchurian Incident. Ishiwara believed that Japan would ultimately come into conflict with the imperialist powers of the West, including the Soviet Union, and, therefore, should avoid protracted war with China (although he himself was partly responsible for its initiation). His solution was to form an equal and friendly federation of Japan, China, and Manchukuo. Ishiwara was one of the chief architects of Manchukuo, but was expelled and excluded from all important positions in the Army when Tōjō came into power there
and gained control of the Army and the central Government, because Ishiwara’s ideas seemed seditious to Tōjō.