What reasons did the Japanese have for attacking Pearl Harbor? (easy points)?

Japan wanted Pacific domination. The US Pacific fleet stood in their way. Said fleet was stationed at Pearl Harbor. Decimating the fleet would make Pacific domination easier.

Yamamoto was an intelligent, patriotic man. He actually spoke out against going to war against the US. When he understood that he would not be able to discourage the Japanese government from its course of war he made sure his nation would have the best opportunity. Pearl Harbor was a plan o eliminate the US Navy so it could not interfere with a rapid capturing of Pacific bases.

Once these bases were captured, it was planned to develop a ring or protection upon which the US would expend men and resources before suing for peace allowing Japan to keep most of its captured empire.

Yamamoto had studied in the US and understood better than most that America wasn't a 'lazy' country (something people still think of the US today).

Because of his stance against the war he spent a lot of time with the ships of the fleet, surrounding himself with people he could trust. The Army didn't like him, and if he had been stationed on land, he might have been forced to step aside, or maybe even killed for his views.

You might want to find his translated letters he wrote for an even greater understanding of the man.

Japan's decision to attack Pearl Harbor had been made in the deeply misguided hope that a sudden knockout blow against the American Pacific Fleet would make it impossible for the United States to intervene against Japan in Asia. Instead, the attack enraged the American people and galvanized them into action.

From Shmoop History/World War II

The Japanese thought the US was the only possible threat to their gaining power so they struck pearl harbor

http://search.yahoo.com/search?p=Japanese+attack+P...

they wanted to eliminate the pacific fleet, but they failed