History: Japan's Attack on Pearl Harbor: the Japanese Perspective

The Western perspective often frames the Japanese attack on Pearl Harbour as a mistake which brought USA into World War. But from the Japanese strategic perspectives, it was seen as a rational, defensive necessity. 

By mid-1941, Japan was in a terminal situation. The U.S. oil embargo on Japan had cut off 94% of their supply. Their economy and military were literally on a countdown to collapse. They could either withdraw from China (which the military saw as a total national humiliation/surrender) or seize the oil fields in the Dutch East Indies.

They knew that if they moved on the Dutch East Indies, the U.S. would intervene from the Philippines. Pearl Harbor was a spoiling attack designed to knock out the only fleet that could stop them from securing the resources they needed to survive.

If Japan had simply invaded Southeast Asia without hitting Pearl Harbor, the U.S. likely would have declared war anyway, but with its entire fleet intact and ready to strike from day one. By hitting Pearl Harbor, Japan bought themselves about 6 to 12 months of absolute freedom in the Pacific. In that window, they conquered Malaya, Singapore, the Philippines, and the Dutch East Indies. 

Without the Pearl Harbour strike, the Japanese Empire might have collapsed in 1943 instead of 1945. In short, Pearl Harbor wasn't a "mistake" by Japan; it was a desperate move by a nation that felt it was already being strangled to death by American diplomacy (oil embargo).