The oil embargo and failure to anticipate Japan

The United States supplied about four-fifths of Japanese oil and treated an embargo as decisive leverage. Japan could obtain only a fraction of the desired replacement supply from the Dutch, so its leaders interpreted the cutoff as an existential threat rather than a negotiating inconvenience. The recipient of a coercive measure decides how threatening it appears. American planners also failed to grant Japan independent strategic thought: if the Pacific Fleet would counter a southern advance, Japan had an obvious incentive to strike that fleet before moving against Malaya and the Dutch East Indies. Diplomacy, resource dependence, and operational planning therefore combined to make Pearl Harbor a logical Japanese target.