In December 2022, Japan revised its National Security Strategy, National Defense Strategy, and Defense Buildup Program, enhancing the Self-Defense Forces’ “counterattack” capability, including by equipping destroyers and submarines with long-range missiles. A look at the significance of Japan acquiring a seaborne strike capability and the challenges facing its submarine program in the Reiwa era.
Submarine-Launched Long-Range Missiles
One of Tokyo’s recently announced defense strengthening measures was to enhance the potency of Maritime Self-Defense Force submarines by equipping them with the domestically developed Type-12 SSM, or surface-to-ship missile, with an extended range of over 1,000 kilometers, and/or Tomahawk cruise missiles purchased from the United States, with a range of over 1,600 kilometers. To do this, the MSDF will explore outfitting its submarines with vertical-launching system modules capable of firing long-range missiles.
The VLS is a modular system where missiles housed in cells in the hull can be launched vertically from ports on the ship’s deck. Modern surface vessels like Japan’s Aegis Combat System–equipped destroyers typically sport up to 100 or more VLS cells. However, MSDF submarines are currently only capable of launching surface missiles like the Harpoon through a limited number of horizontal torpedo tubes in the bow. This requires time-consuming reloading after firing. Submarines outfitted with VLS cells, however, where missiles stored in canisters are pre-loaded into a larger number of firing cells, can launch a higher number of missiles simultaneously or in rapid succession before submerging.
Japan’s Ministry of Defense has therefore decided to develop and experiment with new submarines equipped with VLS modules over the coming decade. In March 2022, the MSDF commissioned the first boat in a new class in its next generation of submarines that is a candidate for such experimentation. The Taigei, meaning “big whale,” is one of the world’s largest conventionally powered submarines at 84 meters long and with a displacement of approximately 3,000 tons. It combines numerous lithium-ion batteries for power storage, while relying on diesel-electric propulsion. It is also designed to accommodate female crew members. The Taigei also brings the MSDF up to its full complement of 22 submarines (up from 16) as originally outlined in the National Defense Program Guidelines in 2010.
According to retired Rear Admiral Fukaya Katsurō, “Japan’s gradual evolution of its submarines over the last 30 years—from the Oyashio class to the Sōryū to the Taigei—have made the MSDF’s subsurface fleet even more powerful.” A former captain of the submarine Sachishio who retired as the commander of Hyōgo Prefecture’s Hanshin Base Corps, Fukaya appreciates the increased capabilities of the Taigei-class submarines. “The increased power means that they can operate more stealthily and don’t need to spend so much time snorkeling, or recharging at the surface—the most vulnerable time for a submarine.”
Dubbed both the “ninjas of the sea” and the “ultimate weapon,” a thick veil of secrecy surrounds the operations of this stealthy platform. During the Cold War, Japan’s submarines were likely engaged in surveillance activities in Japan’s three critical straits (Sōya, Tsugaru, and Tsushima). This was to bottle up the Soviet Union’s nuclear submarines in the Sea of Okhotsk and the Sea of Japan. Their strategic significance remains unchanged today, but the range of their defensive responsibilities has widened as threats emanating from North Korea and China increase.
The mission of Japan’s conventionally powered diesel/electric submarines differs from that of nuclear submarines deployed by the United States. Nuclear propulsion allows submarines to move long distances at full speed while remaining submerged. Japan’s submarines are tasked with patrol duty, using their storage batteries to stay submerged for a long time in one place and monitoring the movement of other countries’ submarines in a given area.
Given the value of this platform, why was Japan’s submarine fleet kept to only 16 vessels for so long? The number was derived from the need to flank each of Japan’s three critical straits with a submarine on either side. With six vessels needed to cover the straits, and factoring in rotations for training, replenishment, and maintenance, 16 was considered sufficient for the Cold War era. However, after the Cold War, and as North Korea and China expanded their military activities, the number of patrol points increased and the missions of the MSDF and its submarines expanded. In 2009, when the Democratic Party of Japan came to power, a decision was made to gradually increase the number of submarines to 22.
Expanding Operations to Japan’s Southwest
The MSDF submarines’ increasing focus on North Korea and China has resulted in their area of operations shifting from Japan’s north to its southwest. However, the progressive enhancement of the American SOSUS sound surveillance system during the Cold War has resulted in the United States Navy being able to constantly monitor the movements of submarines throughout the Western Pacific from the Sea of Japan in the north to the South China Sea. Chinese, Russian, and North Korean submarines now have few places to hide. What, therefore, is the role of Japan’s submarines in the region?
Rather than tracking the movements of other submarines, during peacetime Japan’s submarines are increasingly being used in special missions to approach a target and gathering information without the target’s knowledge. Submarines tasked with such a mission are called “special operations vessels,” and only a few senior officials, such as the vice minister of defense and the chief of naval staff, know the details of these activities. The term “special operations vessel” itself is supposed to be a secret.
During the Cold War, Japanese submarines were purportedly tasked with monitoring Soviet naval exercises off the coast of Vladivostok while collecting images of military facilities along the coast and signals intelligence such as the communications between aircraft and naval vessels, radio guidance signals for missiles, and radar waves used by antisubmarine helicopters when scanning the sea surface. After the Cold War, the subsurface fleet’s role expanded to include the constant monitoring and collection of data on North Korea missile launches from coastal areas on the Asian mainland. In the defense of the Nansei Islands, these submarines can approach an adversary without being detected to gather information and, if necessary, launch attacks.
An increasingly important mission going forward could involve deployment to the geopolitically tense South China Sea. Notably, in September 2018, the MSDF submarine Kuroshio sailed to Cam Ranh Bay, Vietnam. Initially, Japan’s Ministry of Defense only publicized a goodwill visit by three MSDF destroyers. However, just before the group arrived, the MOD announced that they were also accompanied by a submarine training in the South China Sea. The suddenness of the statement was clearly intended to demonstrate Japan’s underwater prowess and signal to China that Japan could operate in the South China Sea, which Beijing increasingly considers its “front yard.” It also constituted Japan’ response to American requests for cooperation on challenging Chinese attempts to change the status quo in the South China Sea.
A Step Toward Autonomous Defense
Against the backdrop of Japan’s rapidly deteriorating security environment, the Kishida administration undertook the revision of Japan’s key security documents with a view to “fundamentally reinforcing Japan’s defense capability.” In the process, Tokyo has taken an important step toward building an autonomous defense capability not solely dependent on the US military.
For submarine operators in the field, morale has purportedly risen in response to plans for enhancing the potency of their vessels with counterattack capabilities. Fukaya believes this will result in Japan’s submarines taking on greater responsibilities, especially during a military contingency. He explains: “Previously, the role of submarines during a contingency was limited to ship attacks and mine laying. They were not allowed to possess counterattack capabilities in line with Japan’s defense policy. The introduction of the Tomahawk means that, in addition to their traditional responsibilities, the MSDF subsurface force will now also be able to leverage the unique characteristics of submarines for offensive operations.”
The first time a Tomahawk was fired from a submarine was during the Gulf War in 1991. If Japan equips its submarines with these weapons their role will change dramatically, making them a powerful “ultimate weapon” for Japan. However, MSDF submarines currently have only six torpedo tubes. While there is a Tomahawk variant that can be fired from these tubes, at any one point two of them will be reserved for torpedoes or other missiles for protecting the submarine itself. That would leave only four tubes available for long-range missiles. Furthermore, once the submarine launches its munitions, the enemy would immediately know its location, and the submarine would have to promptly leave the area. With reloading, it would take some time before the submarine could undertake another strike.
By comparison, the United States Navy’s Los Angeles-class nuclear submarine is equipped with 12 VLS cells. If Japan also equips its submarines with VLS modules, the number of operational targets—including inland targets—will increase, greatly enhancing the potency of these platforms.
Potent but Lacking Personnel
In theory, Japan’s counterattack capabilities could be greatly enhanced simply by increasing the number of submarines. When asked about this, though, Fukaya immediately responded: “We would love to increase the number of submarines, but there is one major obstacle—personnel.”
Indeed, it is well-known that the SDF regularly misses recruitment targets, even at the current level. Fukuya wonders out loud if Japanese politicians are really thinking about the wellbeing of SDF members. He laments: “While the government is moving to double defense spending and purchase various equipment, there is no indication that it is taking seriously the challenge we have in recruiting personnel and the shortage of manpower we can put into the field.”
The retirement age for SDF members is generally set lower than for other civil servants so that the force can “maintain its vigor.” Even though the retirement age has been revised upwards slightly in recent years, SDF members still have to retire at the age of 54–55 for noncommissioned officers and at 55–57 for high-ranking officers. As many as 8,800 SDF members retire from the force annually.
As Fukaya notes, “It’s as if we’re firing nearly 9,000 people still in the prime of their careers every year.” Fukuya believes the government should consider extending the retirement age further and release older SDF members from “combat duties,” such as flying fighter jets or running around on naval decks. Instead, they could be given lighter work or behind-the-scenes desk jobs.
Based on the mantra of “fundamentally strengthening Japan’s defense capabilities,” the implementation of Japan’s Defense Buildup Program is steadily progressing. However, financial support for the personnel who are the heart and soul of the SDF tends to be spread thinly. Due to the declining birthrate and aging population, securing enough workers is a structural problem for the whole of Japan. Bold and drastic institutional reform will therefore be necessary to maintain a robust and highly professional SDF into the future.
Therefore, even if the SDF acquires a counterattack capability through the purchase of stand-off missiles and launch systems, if the human infrastructure that underpins the entire system is weak, Japan’s Reiwa-era defense buildup may only result in halfhearted improvements in Japan’s ability to defend itself.
Source : Nippon