But the U.S. demanded that it withdraw from both China and Manchuria in exchange for a reestablishment of trade for oil. Japan's other major source of oil had been the Netherlands, but the Dutch followed the American's oil embargo in August of 1941. The Japanese resolved to take control of Dutch East India's oil fields. If it did so, it knew war with America was inevitable. "The oil stock Japan had was only for a year and half, and time was running out…if the war was unavoidable and they chose to fight, the longer they would wait the lesser the chance for victory would be because of the limited oil stock, which would be spent even during the peacetime" (Arima 2003). To speed up the course of the war, and to buy time for its oil supply, on December 7th in 1941, the Japanese launched a surprise attack on Pearl Harbor, the U.S. military base located in Hawaii.

Pearl Harbor was chosen because of its strategic importance in a future Pacific War: the Japanese hoped that by bombing Pearl Harbor, the ability of the United States to establish...

The Japanese knew that the U.S. had one of the world's most sophisticated naval fleets. It also knew that a sneak attack, without any diplomatic hints of it occurring was Japan's only hope for success: "By late November 1941, with peace negotiations clearly approaching an end, informed U.S. officials (and they were well-informed, they believed, through an ability to read Japan's diplomatic codes) fully expected a Japanese attack into the Indies, Malaya and probably the Philippines. Completely unanticipated was the prospect that Japan would attack east, as well" ("Pearl Harbor Raid," Naval History, 2010).
Works Cited

Arima, Yuichi. "The Way to Pearl Harbor: U.S. Vs. Japan." ICE Case Studies. Number 118,

December 2003. April 14, 2010.

http://www1.american.edu/ted/ice/japan-oil.htm

"Pearl Harbor Raid, 7 December 1941." Naval History. April 14, 2010.

http://www.history.navy.mil/photos/events/wwii-pac/pearlhbr/pearlhbr.htm