1) Japan had ambitions of expanding its empire across Asia to gain resources and influence. By 1941, its war with China had depleted resources and the US embargo threatened Japan further.
2) Facing economic collapse, Japanese military leaders decided to attack US, British, and Dutch territories in Asia and the Pacific to seize oil and resources.
3) On December 7, 1941, Japan launched a devastating surprise attack on the US Pacific fleet at Pearl Harbor, crippling the American battleships and drawing the US into World War II.