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Taiwan’s Risky Submarine Aspiration

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Taiwan’s Risky Submarine Aspiration

Taiwan’s Indigenous Defense Submarine (IDS) program is not only cost-prohibitive but operationally ineffective.

Taiwan’s Risky Submarine Aspiration

A model of Taiwan’s future submarine as it appeared at a groundbreaking ceremony on May 9, 2019.

Credit: Office of the President, ROC (Taiwan)

An enterprise’s past performance is an indicator of its future performance and, therefore, one of the most relevant factors the government considers when awarding a contract. For a government to grant a $16 billion contract to a company with no past performance of similar technology or scope is unimaginable. But that’s precisely what Taiwan’s government did in 2017 when it contracted CSBC Corp to build eight submarines.

As Taiwan cannot make many submarine subsystems, such as periscope, sonar, or propulsion systems, the unit price tag of each diesel-electric sub is twice as much as comparable subs and not too far behind that of the U.S. Virginia-class nuclear attack submarine. Worse, CSBC conducts little systems engineering, and the government does not exercise independent verification and validation (IV&V) to mitigate technological risks. Consequently, the Chinese consider the program to be high risk with little chance of success. No wonder China has not protested against France and the U.S. for their assistance to Taiwan’s Indigenous Defense Submarine (IDS) program.

There’s a vast gap between Taiwan and China’s submarine forces. The submarine gap cannot be mended even if Taiwan can build and commission eight new submarines in the next few years.

But does Taiwan need to mend the gap?

The People’s Liberation Army Navy (PLAN) is projected to have 76 submarines of all types by the end of this decade, compared to the U.S. Navy’s 66. China’s submarine force, like its Rocket Force, is the cornerstone of its anti-access/area denial (A2/AD) strategy, as stealthy submarines still have an advantage over surface combatants in war. The new PLAN diesel-electric sub, Type 039C/D, is reportedly very quiet and can pose a significant challenge to surface combatants.

In 2005, a Swedish Gotland-class submarine conducted a series of simulated attacks against the United States’ then newly commissioned Ronald Reagan aircraft carrier battlegroup. The Gotland class was the first submarine in the world with a Stirling engine air-independent propulsion (AIP) system, which allows the sub to avoid detection and have an extended endurance for weeks. Throughout the exercise, the Gotland launched (simulated) torpedoes multiple times without ever being detected by U.S. anti-submarine warfare (ASW) assets. The episode shows that an advanced submarine can significantly threaten valuable surface warships. If coming to aid Taiwan in a military contingency, U.S. Navy war planners will have to consider the PLAN’s newly acquired underwater A2/AD capabilities.

That begs the question of why Taiwan continues to build surface warships with limited ASW capabilities while facing the significant PLAN submarine force. To make matters worse, China has had mature anti-ship cruise missile (ASCM) capabilities since the 1960s. The fact that Ukraine sunk the most powerful flagship of the Russian Black Sea Fleet, the Moskva, shows that even a small salvo of ASCMs has a high kill ratio.

A Chinese idiom best describes Taiwan’s naval strategy – hitting a stone with an egg. With China’s rapid build-up of its surface combatants and submarines, Taiwan’s knee-jerk response to build ships in kind and size does not seem to be the outcome of scrupulous assessment and strategic planning.

From the perspective of asymmetric warfare, Taiwan should not compete with the PLAN for more submarines – neither can the island country afford to. To detect and neutralize hostile underwater threats, Taiwan’s military can consider deploying SOSUS (Sound Surveillance System) or SURTASS LFA (Surveillance Towed Array Sensor System, Low-Frequency Active) around Taiwan’s waters. Both systems use arrays of underwater hydrophones to listen for underwater sounds, particularly submarines, and can pinpoint the location of underwater threats. As the area to be defended is not expansive, the cost will be very affordable. To neutralize PLAN submarines, smart naval mines and long-range anti-submarine rockets (ASROC) will be much cheaper and more effective than rival submarines.

Taiwan’s Ministry of National Defense (MND) has never publicized China’s underwater activities near Taiwan. Given the PLA’s almost daily warplane incursions into Taiwan’s airspace and PLAN’s surface combatants menacing near Taiwan’s 12 nautical mile territorial sea line, it is virtually certain that PLAN submarines have been active near or in Taiwan’s maritime territory for quite some time.

There are two plausible explanations for MND’s deafening silence. First, the MND could be afraid of losing face if they announced a PLAN submarine intrusion without any means to neutralize it or at least force it to the surface. Second, as Taiwan lacks SOSUS or SURTASS-like hydrophones to detect the presence of hostile submarines, the military may be oblivious of the underwater threat. Neither case is palatable.

In 2021, the PLA dispatched 961 sorties of warplanes into Taiwan’s air defense identification zone (ADIZ). Over 17 percent, or one in six, were Y-8 ASW variants. Given its unusually high frequency presence near Taiwan’s airspace, it is likely that submarines from the U.S. Navy, Japan Maritime Self Defense Force, or other countries may be cruising under Taiwan’s waters. As Taiwan’s four vintage submarines are antiquated and unlikely to retain much fighting power, it is also conceivable that the PLA’s Y-8 has been conducting ASW drills with its own submarine forces near Taiwan’s waters. Given that the PLA has yet to mature its ASW capabilities, Taiwan’s waters present the best proving ground for the Chinese.

Because any attempt by the PLAN to cross the Taiwan Strait would likely involve an escort by Chinese ASW forces in the air, on the surface, and underwater, these assets will likely make Taiwan’s newly built submarines ineffective. A Taiwanese submarine attacking a group of PLAN surface combatants will essentially embark on a suicide mission because a submarine inevitably reveals its position to the enemy when it launches any torpedoes or missiles. It is difficult, if not impossible, for the sub to escape the firepower from the enemy’s ASW assets when its location is known. Even if Taiwan’s submarines have the opportunity to launch a few torpedoes without being neutralized, they will have to go into hiding immediately. The evasive maneuver would be equivalent to retreating from the battlefield, rendering the underwater force ineffectual.

All of this is to say that the cost-effectiveness of having a submarine force to defend Taiwan is questionable at best.

Operational challenges notwithstanding, Taiwan’s prospect of building indigenous submarines does not look promising. In addition to lacking experience in designing, integrating, manufacturing, and testing submarines, the ambitious plan has been plagued by scandals and mismanagement. Moreover, foreign engineers and technicians cannot seem to keep a secret. The 2024 target date for the first sea trial seems unattainable.

To abolish the IDS program completely would be too hard a pill to swallow for Taiwan’s government. But that does not mean the country cannot change course. If the MND is serious about acquiring submarines, Taiwan should start by building smaller ones, such as those with a displacement of 300-500 tons, and gradually migrate to larger submarines, to those with 1,500-1,800 tons. The accumulated engineering and operational experiences are essential to building an effective deterrent. Otherwise, Taiwan’s aspiration to create a modern underwater force may prove futile.