In recent years, significant attention has been paid to the People’s Liberation Army Navy (PLAN). China’s defense budget, which has increased ten fold in the last twenty five years, has funded the construction of a modern, ocean-going navy. This includes the recently fielded aircraft carrier, Liaoning, as well as fleets of destroyers, frigates, corvettes, replenishment ships, and amphibious assault ships.
The PLAN is indeed an impressive force, but local geography will create challenges during wartime. Japan controls a string of islands that form the Miyako Strait, which Chinese naval forces must transit to enter the western Pacific. Properly fortified, the Japanese-held Ryukyu Islands could conceivably block passage of the Strait altogether.
The Ryukyus have been used to defend Japan before. Okinawa, the gateway to the Home Islands, was fortified by Japan during World War II and then invaded by the Allies. The southern half of the chain, the Sakashima Islands, were used as staging areas for kamikaze fighters during the Battle of Okinawa.
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Japan, which spends roughly a quarter as much on defense as China, could use the Ryukyus to execute an Anti-Access, Area Denial (A2/AD) plan in the Miyako Strait. Like any good A2/AD strategy, such a plan in the Strait would require a fraction of the spending necessary to overcome it.
The PLAN has three fleet commands. The North Sea Fleet, based in Qingdao, is oriented towards the Yellow Sea and beyond while the East Sea Fleet, based in Ningbo, is oriented toward the East China Sea and beyond.
Together, the North and East Sea Fleets field 16 destroyers, 32 frigates, all five of China’s nuclear attack submarines, and around 40 diesel electric submarines of varying ages. Backing this up would be aircraft of the People’s Liberation Army Air Force (PLAAF), the People’s Liberation Army Navy Air Force and the conventionally armed ballistic missiles of the Second Artillery Corps.
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The most direct route for both fleets is the Miyako Strait, a gateway formed by Japan’s Sakishima Islands. A gap 160 miles wide between Miyako Island and the island of Okinawa provides access to the open Pacific and beyond. Chinese naval task forces have recently made a habit of passing through the strait.
It’s difficult to accurately predict a conflict between China and Japan, but in many scenarios China will have to force the Miyako Strait. Japan thus has the advantage of preparing the battlefield, as well as being able to deploy a multi-layered network of sensors and weapons.
The radar network consisting of AN/TPY-2 radars would stand guard against ballistic missile attacks by the Second Artillery Corps. This would be backed up by the Japan Maritime Self Defense Force’s (MSDF) BMD-capable cruisers and destroyers, of which there are currently four. Patriot PAC-2 and PAC-3 interceptors would provide point defense against aircraft and ballistic missiles, respectively.
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The three RQ-4 Global Hawk unmanned surveillance aircraft Japan is reportedly procuring can conduct ocean surveillance, shadowing PLAN ships and providing real-time targeting information to Japan’s joint forces commander. They can also monitor the Chinese mainland, tracking activity at airfields, ports, missile bases and other military facilities.
Finally, although not currently in operation, Japan could deploy an array of hydrophones across the Strait similar to the SOSUS network that covered the Greenland-Iceland-United Kingdom gap during the Cold War. The system would enable Japan to monitor Chinese submarines in peacetime, and efficiently eliminate them during wartime.
The Japanese commander charged with defense of the Ryukyus would take the information from aerial, land, sea and subsea sensors and piece together a coherent picture of the battlefield. The commander could then use this intelligence to preserve his own forces while striking at Chinese forces where they are weak, both technically and professionally.
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Japan’s fleet of 16 submarines, in the process of being increased to 22, will be the most effective active defense. The JMSDF submarine fleet, composed of the newer Soryu and older Oyashio-class diesel electric submarines, is one of the most professional and technologically advanced in the world. The idea would be to direct Japan’s strength in submarine warfare against Chinese weaknesses in anti-submarine warfare (ASW).
Assuming a wartime surge of 11 JMSDF submarines, with a handful to watch the northern frontier with Russia, Japan could form a picket of eight submarines. Operating on a front from Taiwan to the southern Japanese island of Kyushu, the Chinese Navy would need to anticipate an average of one Japanese submarine every 82 miles, an unpleasant prospect.
Aircraft will also play a key role, and the aircraft of the Japan Air Self Defense Force (ASDF) and MSDF would also contribute heavily to the fight. Operating from Okinawa and Kyushu, Japan’s fleet of E-767 and E-2D early warning aircraft would detect enemy aircraft and direct the air battle. F-15J fighters would be vectored to intercept Chinese fighter sweeps. The F-15Js would also be tasked with destroying China’s airborne early warning and tanker aircraft, seriously degrading the People’s Liberation Army Air Force’s ability to operate over Japanese territory.