Great Britain in the Pacific
As American sanctions against the Japanese began to bite, Japan, recognizing that the fall of France meant England could ill afford another war in the Pacific, demanded that the British close the Burma Road. The Burma Road was a critical link for the Chinese which they needed to transport badly needed supplies necessary to their ongoing resistance to the Japanese. Supplies and war materials were landed at Rangoon, and sent by rail to Lashio, one terminus of the road.
This flexing of international muscle by the Japanese occurred in July 1940, a period when the British were strained almost to the breaking point following the collapse of France. Unable to fight the Japanese without the certainty of American support, the British gave in and closed the road. The Burma Road remained closed for three months. During this period the Japanese signed the Tripartite Pact with Italy and Germany, creating the Axis, agreeing that each member would come to the aid of the other if they were attacked by another nation.
The following spring the Japanese entered into a neutrality agreement and non-aggression pact with the Soviet Union, despite the traditional enmity which existed between the two nations. The Soviets had signed a non-aggression pact with the Germans in 1939 and Hitler had not yet invaded the Soviet Union, although by the spring of 1941 preparations for that event were well underway. With Britain effectively neutralized by the war in Europe and with their backs secure from the Russian menace, the Japanese now entered into negotiations with the United States from a position of strength.
Both Washington and Tokyo wanted to avoid a war in the Pacific, at least for the time being. Japan wanted a free rein to extend their Empire. Japan wanted full hegemony over what it called its Greater East Asia Co-prosperity Sphere. This meant occupation of other nations which were placed under the rule of the Emperor. To the United States such conquest was intolerable. The Japanese then demanded that the Vichy government of France allow them to build airfields and bases in Indochina or they would take the French colony by force. Vichy yielded.
When Japanese aggression spread into Indochina FDR cut off all oil exports to the Japanese and as has been seen, froze their assets in the United States. The oil rich colonies of the East Indies were thus targets for Japanese conquest. Had they simply attacked the Dutch and British colonial holdings without first attacking the American fleet at Pearl Harbor it probably wouldn’t have enabled FDR to get a declaration of war through Congress. The US would not have gone to war with Japan to help Great Britain and the Netherlands retain their colonies. The Japanese miscalculated the American response to Pearl Harbor, a risk which they had to take because of their perceived lack of oil.