To paraphrase a political science aphorism, where a nation sits geographically is where it stands strategically. As an archipelago stretching over thousands of miles, then, Japan’s strategic environment is dominated by the sea. A resource-poor nation, Japan depends on free and unfettered passage through sea lines of communication (SLOCs) stretching from the Persian Gulf, past the Indian Ocean, up through the straits of Malacca and the South China Sea, past Taiwan and the Bashi channel, and towards Japan itself. The Japanese islands form a crescent that brackets the Asian continent, giving Japan control over passage from the Asian continent to the Western Pacific Ocean. The sea is by turns Japan’s greatest strength and its most dire Achilles’s heel.
The foundations of Japan’s security, then, are rooted in control of the sea. This is a lesson Japan has learned and relearned through the century and a half since its emergence as a modern state. After routing the Russian Baltic Fleet in a decisive engagement at Tsushima in the Russo-Japanese war in 1905, the Imperial Navy (IJN) was heralded for its strategic and tactical brilliance; yet its disastrous loss at the hands of the U.S. Navy in the Pacific War demonstrated the ruinous consequences of ignoring SLOC defense in favor of focusing almost exclusively on Mahan-style battles for total victory. The IJN’s successor, the Maritime Self-Defense Force (MSDF), was charged with finding a strategy that leveraged the benefits of Japan’s archipelagic geography while avoiding its pitfalls. Facing serious bureaucratic, legal, and financial headwinds, this was not a straightforward task.
After years of drift, the MSDF and their U.S. allies settled upon a joint strategy to deter the Soviet Union, the so-called “Maritime Strategy.” Based on the “Sea Strike” proposal created by (then Seventh Fleet commander) Admiral Thomas Hayward, the Maritime Strategy was a worldwide refocusing of U.S. and allied naval operations on combined arms, employing operations planning to determine the Soviet Navy’s center of gravity and the most effective means of attack. In East Asia, this involved developing plans to strike Soviet naval bases in Russia’s Far East, a deliberate choice to focus on offensive strategies after years of war plans that called for the U.S. Pacific Fleet to swing to the Atlantic in case of general war. The strategy had a twofold goal: keeping the Soviet Navy close to home to prevent Soviet interdiction of allied SLOCs, and tying down tens of thousands of Soviet forces in the Eastern theater to prevent them from swinging towards the Western center of a NATO-Warsaw Pact conflict.
Japan’s role in the development of the Maritime Strategy was critical. Building on the newly negotiated 1978 U.S.-Japan alliance guidelines and Prime Minister Zenko Suzuki’s pledge that the MSDF would defend SLOCs up to 1000 nautical miles from Japanese territory, the MSDF was to utilize its comparative advantage in antisubmarine warfare to bottle up the Soviet Navy in the Sea of Okhotsk, allowing the U.S. navy to focus on its mission of striking Soviet bases. Thus began the oft-repeated turn of phrase that neatly encapsulates the missions of the two allies, that the U.S. is the offensive sword while Japan is the defensive shield. The Maritime Strategy played a key part in shifting Soviet Navy deployments in the mid to late 1980s, which began to deemphasize power-projection into the South China Sea in favor of homeland defense operations. Fundamental to the execution of the Maritime Strategy, however, lay a critical supposition: by the time the U.S. and Japan were to begin executing the strategy, a general war in Europe would already be underway. The only remaining escalation potential would be the usage of nuclear weapons – a vertical rather than horizontal escalation.
Thirty years later, the aspiring East Asian hegemon is no longer Russia, but China. Tasked again with utilizing scarce resources to defend Japan’s territory and the SLOCs that supply the nation with energy, Japanese defense planners have found a means of leveraging Japan’s geography as a force multiplier. The resulting plan can be thought of as a doctrine of denial. By stationing anti-air and anti-ship missiles at strategic points along the Nansei Shoto island chain running from Okinawa down to Taiwan, the SDF aims to make operation through critical chokepoints so hazardous for Chinese forces that any attempt to break out into the Western Pacific will incur unacceptable attrition – in effect denying free passage to People’s Liberation Army Navy (PLAN) vessels and aircraft.
While the geographic locus of strategic planning has shifted, the fundamentals of the “sword and shield” relationship have remained. The denial doctrine fits neatly into the U.S. strategy to defeat China in battle, a plan formerly known as “Air-Sea Battle” but since given the slightly less menacing moniker (albeit more cumbersome) “Joint Concept for Access and Maneuver in the Global Commons” (JC-AMGC). It is unclear if JC-AMGC will call for U.S. strikes on mainland China in the same way that the Maritime Strategy called for attacks on Soviet Naval facilities by U.S. Naval aviation and missile forces. Given the enormous consequences, it is a decision fundamentally left to the political leadership, though a conversation that must be held at all levels of Japanese society given the proximity of U.S. and Japanese bases to the conflict zone. It is a danger largely unlike that of the Maritime Strategy, in which the Soviet Union could not attack U.S. bases in Japan.
While there are distinct similarities in the sorts of alliance operations in each strategy, it is unlikely that the denial doctrine and JC-AMGC will successfully coerce China into keeping its navy close to shore, as was the case with the Maritime Strategy in the 1980s. Whereas the Soviet Union was a vast land power with access to the resources of the Eurasian continent, China depends on SLOCs for energy import much like Japan. Further, there will be no “Western front” to a war with China as there was with the Soviet Union – the denial doctrine and JC-AMGC will not deprive China of reinforcements needed to fight the conflict.
When comparing the Maritime Strategy to the doctrine of denial, then, two things become clear: the denial doctrine utilizes Japan’s unique strategic geography to magnify the impact of its small but potent armed forces, yet it is unlikely to have the same coercive effect in the near term as did the Maritime Strategy. It would be most appropriate to measure the success of the denial doctrine, then, not necessarily by reduced numbers of Chinese ship patrols through Japan’s straits and into the Western Pacific, but by efforts by Chinese officials to finally create the maritime and aerial emergency contact measures designed to avert a catastrophic conflict between the two sides. The denial doctrine itself is based on a strategic framework pioneered by China in recent years (so-called anti-access/area denial), a means of warfighting that is beginning to proliferate across critical maritime chokepoints in the Pacific and Indian Oceans. If successful, Japan’s denial doctrine should convince the Chinese that the techniques they themselves originated bear such dire risks for the prosperity of East Asia that they dial back their coercive behavior, slow down the East Asian arms race, and behave according to commonly accepted rules of maritime and aerial transit.
Even if the denial doctrine is a complete success, it will not stop the continual expansion of the PLAN. China’s economic growth even amidst its recent slowdown is simply too formidable, its resource needs too expansive, and its geostrategic needs too naturally attuned to transit through SLOCs to simply retreat from the Western Pacific as did the Soviet Navy. Instead, by relying on control of the sea as with the Maritime Strategy, Japanese defense planners and their U.S. allies can use coercive and deterrent tools to mold and shape the presence of the PLAN in the hopes of creating a more stable Pacific environment open to transit by all.