From European war to world war

Relations between Japan and the United States had become steadily worse since Japan invaded the Chinese territory of Manchuria in 1931. In 1937, they followed up this success with an invasion of the rest of China. Japan was clearly determined to carve out an empire for itself in South-East Asia.

For Japan such expansion was essential to become the dominant power of the region. Japan's most serious problem was a shortage of vital raw materials like oil and rubber. The militarists who ran Japan decided that the best way to acquire these was to conquer the countries that had them.

These militarists, the commanders of the army, navy and air force, also knew that this strategy was bound to lead them into conflict with the United States, the dominant Pacific power. In July 1941 President Roosevelt demanded the withdrawal of Japanese forces from China and blocked the sale of American oil to Japan. Great Britain, equally concerned about Japan's threat to its colonies in the area, supported the stopping of oil sales to Japan. This oil embargo would have a devastating effect on Japan's military plans since the Japanese bought 80 per cent of their oil from the USA.

Neil Demarco: The era of the Second World War; Oxford University Press, 1993/2000, page 49