Answer: One of the reasons the Japanese controlled its occupied territories was because of the recent trade embargo from the United States.
Explanation: without oil, they would be forced to cease their fighting or give in to the United States demands, if it could quickly conquer the British and Dutch colonies in Southeast Asia and gain complete control of the oil, rubber, and other raw materials it needed, then it could defend its interests in China and Indochina against the europeans, who at this time were currently fighting germany, and were very well at the moment occupied in Europe.
the second reason, based on context was to build a perimeter stretching into the central pacific, hoping to call in reinforcements when the Americans try invading the homeland, or attempt to island hop (this eventually did succeed and their initial plan failed)
hopefully this helped.
