9 April 1940, the spreading of the flames of war into Holland became nearer to being realised. Therefore the Naval General Staff (Gunrei-bu), headed by Admi- ral Prince Fushimi Hiroyasu, on 20 April 1940 formulated the 'Policy towards the Dutch East Indies in the Event of a Violation of the Neutrality of the Nether- lands Proper'. It was considered that sooner or later Holland's neutrality would be violated by Britain, France and Germany, in which case a vacuum would be created, both politically and militarily, in the Dutch East Indies, and moreover that only three countries, Japan, Britain and America, could possibly fill that vacuum. It is known that, therefore, fearing that Japan's economic relations with the Dutch East Indies would come under pressure if Britain or America were to fill that vacuum, the question of despatching naval squadrons, if necessary, un- der the pretext of 'the protection of residents' was examined. 5
Descent into War
The success of the German Western offensive after 10 May 1940 had an impact on the Japanese Armed Forces, as on the rest of the world. They started to think that Germany might win quick victories in the war in Western Europe, and they were apprehensive that, in the event of a consequent peace conference, Germany might extend her influence into the Dutch East Indies, French Indo- China, and Japan's mandated territories in the South Pacific (former German territories). Some of the young officers urged that Japan should make use of this golden opportunity to occupy the Dutch East Indies and secure her position of self-sufficiency. However, these arguments were rejected, as an occupation of the Indies would at some stage lead to a Japanese - American war for which no preparations had been made and moreover in which the prospects for victory were poor. The initial motive for the conclusion of the Tripartite Pact with Italy and Germany was the desire to make Germany recognise Japan's sphere of influ- ence in East Asia, including the Dutch East Indies. Germany wanted by means of the Tripartite Pact to deter America from joining the war against her, but Ja- pan signed the Pact because of a misjudgment over the result of the war in West- ern Europe.
Any army anywhere makes strategic plans for use in the case of emergen- cies, and the Japanese Armed Forces were no exception. The first time that the Annual Operation Plans of the Japanese Armed Forces contained plans for the occupation of the Dutch East Indies was in 1941. It was decided that Army divi- sions would occupy Java and southern Sumatra, an important area for natural resources, while the Navy would occupy Dutch Borneo and the Celebes. Further, the Annual Operation Plans for 1941 included provisions for war against Amer- ica, Britain and Holland, in which event, it was planned to deploy strategic troops in advance in bases in the southern part of French Indo-China and Thai- land.6 It must not be overlooked that this plan was the background to the station- ing of Japanese troops in southern French Indo-China (the Saigon area).