The Japanese attacked Pearl Harbor primarily to neutralize the U.S. Pacific Fleet, which they saw as the biggest obstacle to their expansionist ambitions in Asia and the Pacific. Japan lacked natural resources like oil, rubber, and iron essential for their war and industrial efforts. Economic sanctions and embargoes imposed by the U.S. and other Western nations, especially cutting off oil supplies, threatened Japan's military and economic survival. The attack was aimed at delivering a pre-emptive strike to cripple the U.S. naval power at Pearl Harbor, hoping to prevent a prolonged war and forcing the U.S. to negotiate peace, allowing Japan to secure resources in Southeast Asia without American interference. Key reasons include Japan's need for resources, its policy of establishing the Greater East Asia Co-Prosperity Sphere free from Western influence, and the breakdown of diplomatic negotiations that made war seem inevitable. Japan hoped a surprise, decisive attack would demoralize the U.S. and limit its ability to retaliate quickly, although this miscalculation ultimately led to a stronger American resolve in World War II.
