Why just the American perspective? Americans are idiots, and almost certainly clueless on the matter. The reason for Japan's aggression was driven almost completely by a fear of Japan of becoming a colony of one of the great powers. Colonialism was rampant in Asia, and Japan was very worried they would be another takeover. The US had colonies...Guam, Wake Island, the Philippines, and, at the time...Hawaii (it was not yet a state). Britain has the largest amount of colonies in the Asia...Malaysia, Singapore, Burma, Borneo, and Hong Kong. France had major colonies in Asia...French Indochina (which included Vietnam, Cambodia, Laos and Cambodia). The Netherlands had colonies in Asia...most notably modern day Indonesia. Portugal had colonies in Asia...Macau and East Timor. Japan was literally surrounded by colonies, which meant they were surrounded by empires that were focused on adding colonies. Japan saw that fact that French and England could use their colonies as bases to blockade and attack Japan as a major threat. Japan decided the best defense was to make sure they could be resource independent, in the case of war with France or Britain...or, even the US. For decades, Japan was actually bullied and exploited by both France and Britain...being forced to sign numerous unfavorable treaties. Then, in the late 30's, the opium wars was finally concluded, with Britain conquering much of China, and carving it up into spheres of influence. This one event was the spark that caused the "awakening" in Japan. Japan felt it was now just a matter of time before "they were next." Japan launched the "Meiji restoration," which completely overhauled the military, society and technology...designed to change Japan from an isolationist country to one focused on becoming one that could match the great colonizing powers. They very much adopted the belief that the world was divided into two predators (imperial powers) and prey (the colonized). Japan decided they were going to become one of the imperial powers, to avoid being one of the colonized. So...contrary to the answer you'll get from Americans, Japan was not like the Nazis...seeking "living space." They weren't seeing "world domination." They needed resources to become strong enough to stave off becoming a colony. Their "aggression" was actually defensive...they became the aggressive force they were because the great colonial powers gave them no choice. They attacked America because after Japan attacked Indochina (to neutralize the threat from France), Roosevelt cut off all trade to Japan. Japan was getting 80% of its oil from the US...cutting off that oil would destroy Japan.