Japanese doctrine was a planning system, not one battle slogan

Kantai kessen belonged to a hierarchy of Japanese operational and imperial-defense documents, not to a free-floating slogan. The decisive-battle idea appeared in annual operations plans and informed national-defense strength requirements, policy, and doctrine. Pearl Harbor itself should not be labeled the decisive battle, because the relevant opening ideas were ambush and interception-attrition operations intended to shape a later clash. Each doctrinal phase required a different balance between surprise, damage, and leaving an enemy fleet able to advance. The formal planning language exposes contradictions inside the operational choice.