In Asia, German successes encouraged Japan to call for oil supplies from the Dutch East Indies. Many Western countries reacted to the occupation of French Indochina by banning oil trading with Japan. Japan planned to take over European colonies in Asia to create a great defensive area in the Pacific so that it could get more resources. But before any future invasion, it first had to destroy the American Pacific Fleet in the Pacific Ocean. On December 7, 1941, it attacked Pearl Harbor as well as many harbors in several South East Asian countries. This event led the United States, United Kingdom, Australia, Western Allies and China to declare war on Japan, while the Soviet Union remained neutral. Most of the Axis nations reacted by declaring war on the United States.