Area-air-defence ships and helicopter ASW ships worked together to protect Japan's sea lines of communication. Its submarines and destroyer groups were intended to prevent a repeat of wartime isolation from overseas trade. An expectation that Japan would rebuild an offensive expeditionary fleet could obscure the strength of this sea-lane force. A well-balanced expeditionary fleet can also protect sea lanes, but a fleet optimized for convoy routes and home waters needs more auxiliaries and carrier aviation to project power at distance. The discussion treats submarines as a possible later step in that expansion because it associates large, long-range boats with nuclear propulsion, which Japan tightly controls. Those constraints help explain both the ships Japan built and the capabilities it deferred.
Notable Point · 53:24-56:41
Sea-lane defence shapes the Cold War JMSDF
Japan's helicopter and missile destroyers protected trade routes, while distant expeditionary operations would require more support ships and aviation.