Before the Second World War, one of the smaller European nations, the Netherlands, possessed one of the richest colonies in the world, the Netherlands East Indies (NEI). The Fleet Disarmament Conference at Washington in 1921 had resulted in the Four-Power Treaty, whereby the United States, Great Britain, France and Japan had legitimized the possessions of each of the signatories. Each had separately guaranteed the integrity of the Dutch possessions in an identical note dated 6 February 1922, which gave the Dutch some measure of security. But in the 1930s it became clear that Japan had designs on the Netherlands East Indies.
In those inter-war years, the Dutch were in a quandary concerning their foreign policy, because the NEI security requirements in the Far East began to differ considerably from those of the mother country. The problem was caused by the traditional Dutch foreign policy of aloofness in Europe. After the loss of their Belgian territory, which became a separate kingdom in 1839, the Netherlands lost their status as a European Power, and maintained a strict distance from European political intrigues. This strict neutrality served the country well in August 1914. While the Great Powers savagely attacked each other, the Netherlands stayed out of harm's way and survived the First World War unscathed. As a result of this success, the foreign policy of strict neutrality became a sacrosanct article of faith for the Dutch political establishment in the crucial inter-war period. 
Dutch neutrality during World War One worked to the advantage of imperial Germany but did not imperil the position of Great Britain and France in Europe. However, the situation in the Far East became more complex during and after the war.  The NEI possessed raw materials which would be crucial were Japan to wage war against the USA. Crude oil was the most important strategic material for Japan, which purchased supplies from the United States and the NEI and also imported lesser quantities from British Borneo and Burma. Britain had built an outwardly impressive naval base at Singapore in order to protect her rich colony of Malaya and provide naval protection to India, Australia and New Zealand. A defensive alliance between Britain and the Netherlands would therefore have been logical, particularly after the two countries became allies in the war against Germany following the latter's invasion of Holland in May 1940. To the surprise of British policy-makers in both London and the Far East, however, that did not happen. They had expected a more co-operative attitude from their new-found ally in the Far East, as will be seen below, but Holland for the moment chose to adhere to its cherished neutrality.
This policy proved to be of no benefit at all to Dutch Far Eastern possessions, but it took the Dutch government quite some time to recognize the fact. Owing to strong internal as well as external pressures, the Dutch foreign policy of aloofness was gradually abandoned over the course of a single year, and the Dutch declared war on the Japanese directly after Pearl Harbor -- without having been attacked and without any security guarantee from Great Britain or the United States. This amazing change in a foreign policy that had prevailed for more than one hundred years is the subject of this article.
The Dutch Government and Its Colonial Administration
The Dutch Government was represented in the NFI by a Governor-General was responsible to the Minister of Colonies. The colonial administration was divided into a number of Departments (nine altogether), the heads of which were subordinate to the Governor-General. In May 1918 the NEI administration established a semi-parliamentary institution called the People's Council (Volksraad) which consisted of 60 members. Of these, 30 were indigenous, comprising half of the Volksraad, 25 were of Dutch nationality and five represented the Chinese and Arab populations in the NFI. …