Categorized | China, National Security

Submarines a Flashpoint in China-Japan Island Rivalry


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Submarines a Flashpoint in China-Japan Island Rivalry

March 1, 2013 |


Chinese military ships have dropped mysterious buoys near the disputed Senkaku/Diaoyu islands in the East China Sea, a tactic usually associated with tracking submarines and a glimpse into possible underwater warfare going on between Beijing and rival Japan. An undersea battle is not likely, but the intense activities of dueling submarines raise the odds that a mistake, accident or miscalculation could lead to a larger clash on the sea surface or in the air.

As LIGNET explains, China has the numerical advantage in submarines, but Japan has more modern and ultra-quiet subs with better trained crews. Control of the islands is not about natural resources; rather, smooth underwater sea lanes are critical for China’s ballistic missile submarines, which someday will carry nuclear warheads. Japan’s maritime self-defense strategy depends on steadfastly denying Chinese subs a safe haven for operating.


Several maritime confrontations have taken place this year near the disputed Senkaku/Diaoyu islands. Both China and Japan claim the other has encroached in a threatening manner in the East China Sea. Japan’s defense ministry alleged in January that a Chinese frigate locked its weapons radar system on a Japanese helicopter and, in an earlier instance, engaged its targeting radar on a Japanese destroyer.

In mid-February, Japanese military commanders and politicians became indignant when Chinese vessels from the State Oceanic Administration, a type of coast guard, were seen deploying buoys near the islands. The buoys, according to Japan, were placed less than 1,000 feet from Japanese waters.

The Japanese believed that these buoys are meant to track their submarines in the East China Sea operating near the five uninhabited islands. On February 26, the Chinese Foreign Ministry denied the accusations and said that the buoys were only being used to conduct scientific “maritime weather observations.”

Sonobuoys and Undersea Warfare

China’s navy has the capability to deploy sonobuoys, a critical tool of undersea warfare used to track enemy submarines. Sonobuoys are often dropped by airplane or deployed by ship. They emit a passive sonar signal and then radio this acoustic information back to friendly airplanes, submarines or surface ships.

China’s main anti-submarine airplane is the Y-8X. It can deploy sonobuoys and use infrared detection equipment to track submarines. The Y-8X is a turbo-prop aircraft often used to patrol the East China Sea in the area of the disputed islands.

Japan believes that at least one Y-8X entered its air defense identification zone on January 10, just north of the Senkaku/Diaoyu chain. In response to this provocation, both countries quickly scrambled fighter planes to the location. The tense situation eventually subsided and both China and Japan sent their aircraft home.

Y-8X patrols have been spotted in the area beginning in 2010. Based on reports, it is then plausible that the Y-8X will drop or already has dropped sonobuoys to track Japanese submarines.

Easier Submarine Passage

The disputed islands are located in an area that has rich natural resources, including oil, gas and fisheries. But control of the islands also is a strategic necessity for smooth submarine operations for both China and Japan.

For the Chinese navy, the islands serve as a northern gateway and potential safe haven for easier passage by its submarines, according to a retired Japanese admiral quoted in November 2012 in The Japan Times. Beijing uses these critical undersea lanes to transit from the South China Sea into the western Pacific to move closer to the United States, the report stated.

China especially needs these unimpeded waterways for its new nuclear-powered ballistic missile submarines. Meanwhile, Japan’s Maritime Self Defense Force submarines fiercely attempt to deny access to Chinese subs and to thwart their free movement by constantly patrolling and snooping in the deep near the disputed islands. These undersea tactics could lead to a flashpoint, either by an accidental or intentional attack involving submarines.

The Chinese navy has 50 submarines in service, according to the Pentagon’s 2012 report on China’s military strength. China’s most significant addition to their undersea warfare capabilities are the new Jin-class (Type-094) nuclear-powered ballistic missile submarines (SSBNs). Two are currently believed to be in operation. The SSBN’s will be equipped with JL-2 nuclear-tipped missiles within the next two years.

Beijing also has two nuclear-powered attack subs, called the SHANG-class, but most of their subs are diesel-powered. At least four of the most modern YUAN-class diesel models diesel models are operational. This includes 13 older SONG-class boats. The YUAN- and SONG-class units can carry anti-ship cruise missiles. The rest of the fleet consists of 12 outdated Russian-made Kilos and other obsolete units.

Japan has just 15 active attack submarines, but what they lack in numbers they make up for in performance. Four of the Soryu-class ultra-quiet diesel-electric subs were activated in 2007, with top-notch sensory equipment. Eleven of the Oyashio-class low-noise boats developed in the late 1990s also patrol regularly.

The Japanese coordinate some of their patrols with the U.S. Navy in the South China Sea. Admirals from the Japanese submarine service are confident that with U.S. assistance they could “find, track, and sink” any Chinese sub, according to the Japan Times report.


LIGNET believes that undersea operations involving Chinese and Japanese submarines are an overlooked but very important aspect of potential conflict near the Senkaku/Diaoyu islands. A miscalculation by submarine commanders or other type of accident or mishap could lead to an incident that would unnecessarily provoke a larger naval or aerial response.

LIGNET also judges that the buoys deployed this month are decoys to mask the deployment of real sonobuoys that have already been dropped by Chinese anti-submarine aircraft.

It is difficult to simulate what an undersea battle would look like between China and Japan. China has superiority in numbers and advantages in better nuclear-propulsion. But its submarine program has been inconsistent in the past.

Most of China’s subs, however, are noisy diesel models. They lack modern sonars and sensors to track opposing submarines or surface vessels and are without the latest undersea communication gear. China’s submarine doctrine reportedly is more focused on going after surface vessels with torpedoes and not for interdicting and tracking enemy subs.

Japan is outnumbered, but its attack submarines are more advanced and less noisy. The Japanese, as a self-defense force, also place much more emphasis on training and devote more resources toward anti-submarine warfare. They make their submarine fleet a high priority and have done so for decades. This results in higher proficiency and competency in their officers and crew.

However, the Japanese Maritime Self Defense Force doctrine makes the assumption that it always will have the U.S. Navy to help it with anti-submarine tactics.

Unfortunately, American submarines and other anti-submarine assets may not be able to intervene in a submarine confrontation between China and Japan. This would force Japan to engage the Chinese submarine fleet on its own. It is for this reason that LIGNET gives Beijing a slight edge in undersea warfare if hostilities break out and America stays on the sidelines.

The most important development for China is its nuclear-powered ballistic missile submarines. If the Jin-class SSBN becomes fully capable with its JL-2 nuclear tipped missiles, it will change the deterrence equation in the Western Pacific. These missiles are believed to have the ability to reach the United States.

That is why control of the disputed islands is so important for the Chinese. Using the Senkaku/Diaoyu chain as a gateway and safe haven would allow these “boomers” to roam in the Western Pacific and that would change the nuclear strategic superiority that the United States hopes to maintain.


Regarding the waters around the disputed islands, it appears the Chinese have been more forward-leaning and are ahead of the game by using anti-submarine aircraft and perhaps sonobuoys to track Japanese submerged or surface vessels. The Japanese, while more skillful at undersea warfare, still need the Americans to counteract China and neutralize its numerical advantage. Neither China nor Japan wants war, but one underwater miscalculation or accident could lead to an escalation of hostilities between the two rivals.


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