Taiwan’s Indigenous Defense Submarine (IDS) program is, alongside the rising indigenous drone sector, one of the nation’s most ambitious military plans of recent years. However, while drones are meant to enhance asymmetric capabilities, submarines endorse a different role in Taiwan’s defense –– one that is not well defined.
Indeed, while the power balance continues to lean in favor of China, the IDS program’s costs and length seem to make little sense with what Taiwan really needs. The mismatch between what is required to conduct asymmetric warfare and where investments are made raises serious questions regarding Taiwan’s preparedness in the face of a growing assertive China.
The IDS program reinforces prestige, self-reliant capabilities, and, potentially, deterrence. Yet, it does not align with what analysts and experts have long identified as major weaknesses in Taiwan’s defense apparatus. The critical element of Taiwan’s defense strategy is denying China the possibility to land if it invades.
As the People's Liberation Army Navy (PLAN) continues to expand its capabilities, Taiwan’s Navy faces pressure to modernize its fleet. However, the question remains whether indigenously built submarines represent the most effective allocation of defense resources, or whether they constitute a prestige project that diverts funding from more urgent asymmetric capabilities.
In this light, what is the logic behind the pursuit of the IDS?
Deep dive
Taiwan has sought to develop indigenous submarines for the past three decades, with the first program implemented during former President Chen Shui-bian’s (陳水扁) administration.
Taiwan’s small fleet is currently composed of four submarines –– two Hai Shih-class, both commissioned 80 years ago, and two Chien Lung-class commissioned back in 1987 and 1988. Meanwhile, China’s fleet contains 59 submarines and is expected to keep growing.
Taiwan’s IDS is a response to address allies’ hesitation to provide submarines to Taiwan in light of Chinese pressures. In 2001, Washington agreed to provide eight submarines to Taiwan, before stepping back following a stalemate in the Legislative Yuan, issues related to costs, and the Obama administration’s decision to halt sales.
Compelled by foreign acquisition constraints, Taiwan turned to indigenously built submarines to modernize its capabilities. Hence, in 2014, the Navy formalized the IDS program, targeting the development of eight submarines.
In 2016, CSBC Corporation, Taiwan’s state-owned company, became the main contractor. To address its lack of experience in building submarines, Taiwan received external support from international allies.
The lead submarine costs NT$51.1 billion (US$1.64 billion) for 2019–2025, a figure raised by the investment required to build a new production facility at CSBC’s Siaogang complex in Kaohsiung. The full program, originally planned for up to eight boats over 25 years, could total about NT$405 billion.
Unveiled in September 2023, the Hai Kun is armed with US Mk 48 heavyweight torpedoes, and can house Harpoon anti-ship missiles, as well as potentially sea mines, that could sustain the Navy’s efforts to counter an encirclement by China.
The construction of the eight submarines would undoubtedly enhance the Navy’s defense capabilities, raising its deterrent power, and supporting its operations across the strait.
Even so, at the same time, the program has been plagued by internal turmoil: delay and political polarization have eroded trust and raised concerns. At first glance, the IDS program has been a long and complex project.
But how does it fit in Taiwan’s broader defense strategy?
Is it needed?
Submarines, because of their greater survivability and significant deterrent potential, have long been perceived as critical for Taiwan’s defense. Submarines can serve to protect Taiwan's biggest vulnerabilities, such as undersea cables and energy supply.
Submarines have also been envisioned as key elements to contest a Chinese quarantine, operating covertly to threaten PLAN vessels enforcing a blockade. However, several factors undermine these optimistic assessments and raise fundamental questions about the program's strategic value.
First, Taiwan does not possess the required technological R&D and shipbuilding capabilities to properly implement its program, which has raised costs and extended timelines while reducing the future combat effectiveness of the Hai Kun because of limited access to foreign equipment.
Second, the high cost of the program –– more than twice Japan's Taigei-class submarine price –– and its relative share of the annual defense budget divert funds from other aspects of national defense that could be more efficient for Taiwan's security imperatives. Building and reinforcing asymmetric capabilities have been identified as the most effective way to respond to China's massive firepower.
Submarines are being envisioned as a tool to break a potential encirclement by China. Yet, other low-cost instruments may exist: the war in Ukraine highlighted how sea drones have effectively enabled Kyiv to win the maritime battle in the Black Sea despite facing a superior Russian naval force.
Taiwan could acquire hundreds or even thousands of maritime drones for the cost of a single submarine, creating distributed threats that would be far more difficult for China to neutralize.
Third, while submarines’ survivability may indeed be higher than other high-profile assets, China’s submarine detection capabilities are quickly evolving, suggesting that Taiwan’s fleet could also be located and destroyed by China’s anti-submarine warfare.
Given the existential threat that Taiwan faces, every cent must be carefully spent to enhance its survivability. The IDS program risks diverting its limited resources from more cost-effective military capabilities. Mobile coastal defense missiles, naval mines, fast attack craft equipped with anti-ship missiles, and drone systems offer far greater defensive value per dollar spent.
Reassessing priorities
While submarines might contribute to deterrence and provide operational capabilities, there is a pressing need to properly weigh whether the benefits outweigh the risks, and whether a small fleet of submarines can effectively enhance Taiwan's “overall defense concept.”
Experts have suggested that Taiwan should request support from an independent verification and validation team to strengthen and structure its submarine program.
Taiwan must not disperse its military budget on outdated strategies that echo a time when the authoritarian KMT, paired with the US, enjoyed military superiority over the Chinese Communist Party. That era has long passed, yet Taiwan's defense establishment continues to gravitate toward conventional assets that mirror those of major powers rather than developing capabilities appropriate to Taiwan's actual security landscape.
While Taiwan has complemented its high-profile and expensive military assets with cheaper, larger quantities of smaller anti-air and anti-ship systems, this approach is not systematically pursued, therefore raising questions regarding Taipei’s commitment to asymmetric warfare. In Taiwan’s defense planning, “asymmetrical” does not naturally correspond to a large number of low-cost assets, which in turn leads to massive investment in high-profile systems.
While these high-profile assets may be useful to counter China’s gray-zone tactics during “peacetime,” they may prove inefficient for Taiwan’s biggest need –– ensuring its survival during a blockhead or an invasion. This conservative approach from the Ministry of Defense represents a fundamental misalignment between Taiwan's stated asymmetric strategy and its actual procurement priorities.
Lai Ching-te’s (賴清德) administration seems to have understood better than previous incarnations the necessity to establish a credible porcupine strategy, emphasizing urban warfare preparations and increased investment in drone technology. However, military culture, limited budgets, and a fragmented political landscape continue to hinder development.
Taiwan's survival depends on making hard choices about defense priorities. The submarine program, for all its symbolic appeal, represents a dangerous distraction from the unglamorous but essential work of building a defense posture that can actually deny China the ability to strangle Taiwan or invade it militarily.
