Simple answer of which 90% of the pieces have already been placed.
1. The US had cut off oil supplies to Japan because of the attacks on Manchuria.
2. Oil supplies in Japan would only allow the Japan a 6month war with the US.
3. It was decided to eliminate the US naval presence in the Pacific area thereby rendering the millitary ability of the US to 0. (at that time planes could not traverse the pacific ocean, ships were required).
4. By eliminating the Naval ability of the US, Japan would be able to secure resources in SE asia to help sustain their war effort (a major point of this was the capture of the phillipines)
5. They had ill founded hope that the US would take 2 years to rebuild any significant Naval ability in the pacific. This proved to later be false when the US launched 18 new ships within 6months of Pearl. Not only this, they salvaged all but 1 ship (the arizona, believed to be too badly damaged with 8 hits) from the bottom of Pearl and had most if not all repaired within 6-12months.
This is also a good lesson in intelligence and listening to your millitary. The admiral that attacked the US at pearl had attended an American university for a period and is on record saying that Japan could not sustain a long war with the US, he had hoped to get the US to a cease fire within 6months. Possibly by securing SE asia and starting peace negotiations with US. Japan severly underestimated the industrial capacity of the american infastructure. Detriot switched within 2 months from making cars to tanks and aircraft. Boeing was created almost overnight.
Basically Japan was trying to elimate our ability to assist in the pacific theatre, up until the bombing the US had a neutral stance in the pacific but had been assisting China and the US was aware that we would be become involved eventually (probably with the attack on the phillipines and the Batan death march).
WWII was a war about resources, we elimated Japans resources and thereby eliminated most of their ability to fight. (Kamikazies were created because Japan often had the planes, the pilots, and only half the fuel required. In the end of the war they were cutting down every tree in Japan and making ethanol out of them to have fuel to power their war machine.