Are subs the best answer to China's growing military power?Taiwan’s submarine saga is back in the news again. For decades, successive governments have been determined to upgrade and expand the nation’s limited undersea warfare capabilities, albeit without much success. The Republic of China Navy (ROCN) currently has two operational submarines, which were acquired from the Netherlands during the late 1980s, along with a pair of U.S.-supplied boats, which date back to the 1940s and are used for training. In 2001, the George W. Bush administration agreed to sell Taipei eight diesel-electric submarines (SSKs) as part of a broader arms package. Because the United States only builds nuclear-powered boats, however, and because potential European partners were reluctant to help in the face of Chinese opposition, that deal never materialized.
With the United States unwilling to fulfill its previous commitment, patience appears to be running out in Taipei. According to recent press reports, the government is preparing to embark on an indigenous submarine construction program, although it has not abandoned the option of foreign procurement entirely. Specifically, it plans to build at least four and as many as eight SSKs. Although the details have not been finalized, the boats are likely to displace around 1500 tons each—smaller than its current submarines but comparable to the size of many platforms manufactured in Europe. This would be a major undertaking for a nation with no previous experience in the submarine-building business.
Nevertheless, it is hardly surprising that Taiwan wants to improve its submarine force. As a small island nation located just 100 miles from its much larger rival, it occupies an unenviable strategic position. Until as recently as a decade ago, Taiwan enjoyed a military edge over the People’s Republic of China (PRC), and could expect to mount an effective defense against the PRC, especially if it tried to mount an invasion.
This is no longer the case, though. Beijing has been steadily modernizing its armed forces and developing a variety of capabilities that could be used to coerce Taipei or counter third-party intervention on its behalf. As a result of this shifting balance of power, Taiwan can no longer count on controlling its surrounding waters or the airspace above them. Instead, the best it can probably hope for in the event of a cross-Strait conflict is to impose heavy costs on the PRC by holding out as long as possible. Given China’s growing military strength, that will require an “innovative and asymmetric” military strategy, in the words of Taiwan’s Ministry of National Defense.
At first glance, SSKs seem like exactly the type of asymmetric capability that Taiwan needs to offset China’s military power. For instance, they could help to defend against a seaborne invasion, whether by targeting amphibious assault ships in port or interdicting them en route. They could also be used to threaten enemy surface combatants that attempt to impose a maritime blockade and cut the island off from the global economy. On closer inspection, though, SSKs might not be a good fit, for two reasons.
First and foremost, SSKs are expensive—perhaps too expensive for Taiwan. In 2001, when it wanted to purchase eight 2000-ton submarines from the United States, the estimated price tag was $10-12 billion. Building them at home would not be any cheaper. Press reports indicate that the Ministry of Defense plans to spend almost $5 billion on the first four boats alone. To provide some context, Taiwan’s annual defense budget is approximately $10.5 billion, and has remained relatively flat for years. That situation doesn’t appear likely to change any time soon. In fact, it could get worse. Competition for Taiwan’s scarce defense dollars will only become more intense as it shifts to a smaller but more expensive all-volunteer force, and as it attempts to recapitalize its aging destroyers, frigates, and amphibious transport ships.
This bill might be worth paying if SSKs would provide Taiwan with significant “bang for the buck.” Yet there are reasons to doubt that they would. Quiet, well-armed, diesel-electric submarines can be an extremely effective sea-denial capability when they are under way. But not all of them will be. Even if Taiwan managed to procure eight new boats, only a fraction would be available for service at any given time, and that fraction could be quite small. With only two operational submarines at present, the ROCN would have to increase the size of its undersea warfare community to sustain a significantly larger fleet. If it has trouble filling those billets—and the recruiting challenges it has faced during its shift away from conscription suggest this is a very real possibility—then the availability rate of its submarines would correspondingly suffer. Moreover, submarines in port might be some of the first targets in any Chinese attack. Beijing could even become increasingly willing to escalate without warning if it meant catching Taipei off-guard and preventing it from putting as many boats as possible to sea.
Of course, any SSKs roaming the Strait or guarding Taiwan’s eastern coast would pose a major challenge for China. There are significant limits to the amount of damage they could do, however. 1500-ton submarines can only carry a small payload of torpedoes and anti-ship missiles, and the ports where they could reload might very well be damaged, destroyed, or closely monitored by Chinese air and naval forces waiting for Taiwanese boats to return. At the same time, while China’s anti-submarine warfare (ASW) capabilities might not be very formidable at present, Beijing is likely to place an increased emphasis on this area once Taiwan poses a more serious undersea threat. With Taiwan’s first indigenously produced SSK not expected to be ready until 2025 at the earliest, the PRC would have plenty of time to enhance its proficiency at ASW.
Concerns about cost and effectiveness also go hand-in-hand. Because submarines in port are so vulnerable, and because they would represent such a large and important investment, Taiwan might go to great lengths to defend them against a possible attack. It has already devoted considerable effort to protecting its combat aircraft, for instance by constructing a hardened base inside a mountain that can support hundreds of fighters. Notably, when Taiwan was hoping to purchase new submarines from the United States more than a decade ago, there were reports that it wanted to build a similar facility to protect them from a surprise attack, although the price was probably far beyond what it could afford, given the resources projected to be available for defense.
In the end, with the military balance in the Strait clearly shifting in China’s favor, Taiwan needs asymmetric capabilities to bolster deterrence and improve its chances if a conflict breaks out. But SSKs may not be part of the equation, whether they are built at home or purchased abroad. In fact, Taipei’s overriding focus on submarine acquisition risks creating tunnel vision that crowds out innovative thinking about other asymmetric options, while purchasing SSKs would impose enormous opportunity costs, particularly for a nation with a defense budget as small as Taiwan’s.