Japan's crack submarine fleet

Updated : 23.08.2016 / Category Sentaku in The Japan Times


China has lately been resorting to defiant and audacious acts like claiming its territorial rights over waters around artificial island it has built in the Spratly Islands in the South China Sea and unilaterally designating an air defense identification zone in the East China Sea.

While these acts are visible to all, the real front battle line lies deep in the sea where submarines are principal players. This article attempts to provide in-depth descriptions of the real picture of submarines of the Maritime Self-Defense Force and their roles, as little has so far been made known about them.

During the 1998 Rim of the Pacific Exercise off the coast of Hawaii, Adm. Archie Clemens, commander in chief of the U.S. Pacific Fleet, was dumbfounded as a monitor screen showed that eight vessels of his fleet were "attacked and sunk" one after another by a single MSDF submarine.

In the subsequent RIMPAC exercises, MSDF submarines and surface ships have maintained the upper hand. One U.S. naval officer said that those submarines were the last thing he would like to fight, adding that if they got really serious it would become impossible to continue the exercise.

The reason that has led the United States to give such a complimentary evaluation of MSDF submarines is that they perform at such a high level that even the general Japanese public has trouble grasping just how good they are. This ability stems from two factors: one is the subs' performance characteristics that are superb even by global standards and the other is the high levels of training that their crews go through.

At present, MSDF submarines are built by two firms—Mitsubishi Heavy Industries and Kawasaki Heavy Industries, both boasting the highest technological standards in the world. Mitsubishi excels in welding skills. The welding skills used for nuclear reactors are also used for submarines. Kawasaki is known for its expertise in reducing vibrations. Silence is essential in preventing submarines from being detected by the enemy.

The high levels of training that MSDF submarine crews have been given should be viewed in a historical perspective. The central headquarters of both the U.S. Navy in Japan and the MSDF are located in Yokosuka, Kanagawa Prefecture, and MSDF submarines' operations are effectively integrated with the U.S. Navy.

During the Cold War, the U.S. Navy entirely entrusted to MSDF submarines the role of watching the movements of Soviet submarines in the Soya Strait between Hokkaido and Sakhalin, the Tsugaru Strait between Honshu and Hokkaido, and the Tsushima Strait between Kyushu and South Korea.

The American reliance on those MSDF submarines stemmed from their excellence in small-turn performance. They are capable of navigating over topographically complicated sea floors with steep uphills, gorges and tangled sea currents in pitch-dark conditions, usually moving at a speed of 5 knots. Today, MSDF submarines can trace every movement of Chinese naval vessels, including subs, from their port departure to every point of their routes, by utilizing an analysis of information sent from U.S. reconnaissance satellites as well as of radio waves.

Before the collapse of the Soviet Union, the MSDF had 16 submarines and deployed three each in the Soya, Tsugaru and Tsushima Straits with the remaining seven under repair or engaged in training exercises. Lately though, with the rise of Chinese naval power, many of the MSDF submarines are being shifted to waters around the Nansei Islands (the island chain between Kyushu and Taiwan). The MSDF, which now has 18 submarines, plans to raise the number to 22 by 2018.

Critical areas of the MSDF submarines' activities aimed at China are the Tsushima Strait, the Miyako Strait between Okinawa Island and Miyako Island, and the Osumi Strait off the southern tip of Kyushu, each of which constitutes a passageway through which Chinese naval vessels must pass to move from the East China Sea to the Pacific Ocean.

A high degree of confidentiality is maintained on the whereabouts of each submarine. The crew members are not allowed to tell their families where they are going or how long they will be away. It is only about once a year, if at all, that an MSDF patrol aircraft or surface ship detects any of the MSDF submarines. And such thoroughgoing confidentiality is highly appreciated by the U.S. Navy.

Moreover, the MSDF submarine crew members possess outstanding skills for detecting the position and movement of enemy vessels by analyzing and processing the sounds emanating from them. The subs' sonar equipment, including a towed array sonar trailing behind a submarine for several hundred meters, has the capability to detect sounds coming from a vessel up to 80 km away.

Each submarine is staffed with a crew of about 70, all of whom have passed severe psychological aptitude and air pressure resistance tests. Since their mission calls for a long stay in a completely sealed space, they must be able to cooperate with their colleagues and cope with stress.

Some time ago, Adm. Wu Shengli, commander of the Chinese People's Liberation Army Navy, told a high-ranking Self-Defense Forces officer that his navy was aiming to become a "blue-water navy," meaning that it would become capable of operating across the deep waters of open oceans. In the 1990s, China was known to have only a "brown-water navy," which can operate only in rivers and coastal areas. True to Wu's words, China has since been endeavoring to expand its areas of operation into the Pacific.

The East China Sea, where MSDF submarines are deployed, has long stretches of continental shelves, making the average depth only 180 meters, and some areas only 50 meters. That is why China now looks to the South China Sea, where waters are 3,000 to 4,000 meters deep in a number of areas, and has concentrated its state-of-the-art submarines in the South Sea Fleet.

That has led the Japanese Defense Ministry to keep an eye on the 150-km-wide Bashi Channel between Taiwan and the Philippines, which could be used by Chinese submarines as a gateway to the Pacific, which in turn could rapidly increase confrontation with MSDF submarines around the Bonins and other Japanese islands in the Pacific.

The capabilities of MSDF submarines today far surpass those of their Chinese counterparts. But an MSDF officer has warned that if China secretly obtains advanced technologies from various countries and combines them like a jigsaw puzzle, the day may come when Chinese submarines will be on a par with those of the MSDF.

A high-ranking government official has said, meanwhile, that with the passage of the security legislation pushed by the Abe administration, the Self-Defense Forces now have the authority to use weapons to protect U.S. forces during joint patrols or to even exercise the right to collective self-defense.

But unlike most major powers of the world, Japan effectively does not have rules of engagement, which define the circumstances, conditions, degree and manner in which the use of force may be permitted. This situation, a direct result of the laziness on the part of politicians, is forcing the MSDF submarines and their crews to sail in pitch-dark waters bearing the consequences of politicians' laziness.


This is an abridged translation of an article from the November 2015 issue of Sentaku. The original article can be found here.