Taiwan’s new submarine throws spanner into China's invasion plans

Taiwan’s new diesel-electric submarine Hai Kun advances strategic deterrence, enhancing stealth capabilities to complicate China's military planning.

Taiwan’s first homegrown diesel-electric submarine, the Hai Kun, completed its third sea trial on July 3. According to the original schedule, the manufacturer—CSBC Corporation—is set to complete all sea trials by the end of September and deliver the vessel before the end of November.

Rear Admiral (ROCN ret.) Hsia Kuang-ya (夏光亞) told TCN that the strategic blueprint for Taiwan’s IDS initiative was conceived in 2014 by the then-Commander of the Navy, Admiral Chen Yeong-kang (陳永康).

Hsia told TCN that when the initiative was being planned, Admiral Chen evaluated Taiwan’s strategic realities and threat environment and concluded that even a fleet of eight to ten submarines might be insufficient—not for offensive purposes, but to serve as a strategic deterrent capable of complicating adversarial planning and reinforcing Taiwan’s asymmetric defense posture.

From an operational perspective, submarines represent one of the most decisive tools in modern warfare. Their stealth, survivability, and latent lethality provide not only tactical advantages but also exert a unique psychological pressure on opponents. While initiating an attack would compromise a submarine’s concealment, the very knowledge that a submarine may be silently operating in contested waters introduces significant uncertainty for any potential aggressor.

This invisible threat has the potential to persuade Beijing to adopt a more cautious and conservative approach when calculating military moves toward Taiwan, Hsia added.

The force to counter growing undersea threats

The development of Taiwan’s indigenous submarine fleet not only bolsters its deterrence posture but also contributes significantly to enhancing the ROCN’s anti-submarine warfare (ASW) capabilities.

According to the US Department of Defense’s "2024 China Military Power Report," the People’s Liberation Army Navy (PLAN) is projected to operate 65 submarines by 2025 and 80 by 2030.

This growing undersea fleet poses a serious threat to Taiwan’s national security and holds the potential to alter the strategic balance in the broader Indo-Pacific.

In this context, Taiwan’s effort to develop homegrown submarine capabilities goes beyond acquiring advanced naval platforms—it also aims to foster operational readiness in ASW doctrine and training.

Even a modest fleet of submarines significantly enhances a navy’s ability to prepare and evolve counter-submarine strategies. Taiwan’s submarine program, therefore, plays a critical role not only in national defense but in upholding regional maritime security.


Industrial gains from Taiwan’s indigenous submarine program

Beyond its military applications, the IDS program has stimulated meaningful industrial upgrades and strengthened Taiwan’s defense resilience. Rear Admiral (ret.) Hsia noted that the program has engaged over one hundred local suppliers, contributing components such as high-grade structural steel, pressure-tight sanitary systems, hydraulic modules, and noise-reduction HVAC units.

These companies have demonstrated their ability to meet the stringent demands of submarine construction, turning the IDS project into a cornerstone of industrial innovation and supply chain integration.

According to former CSBC Corporation Chairman Cheng Wen-lung (鄭文隆), roughly 85 Taiwanese firms were involved at the start of the Hai Kun-class prototype’s construction. By mid-2024, the number of qualified domestic suppliers participating in the IDS follow-on production had grown to over 140, illustrating the rapid maturation of Taiwan’s indigenous defense industrial base, Cheng said.

Moreover, Cheng indicated that the CSBC has actively encouraged foreign vendors to establish production facilities or invest directly in Taiwan, receiving increasingly favorable responses.

In 2023, nine Taiwanese domestic suppliers issued a joint statement emphasizing the strategic significance of Taiwan’s indigenous submarine program. According to the statement, the initiative offers multiple benefits. Chief among them, in the statement, is strengthening national defense autonomy, which is viewed as the most crucial element in advancing the defense industry. The suppliers noted that several key components and core materials can already be manufactured by local companies.

The statement also underscored the importance of embedding defense capabilities within civilian industrial capacity, thereby fostering a more resilient defense foundation. The suppliers also highlighted the value of establishing a robust domestic supply chain to support long-term defense needs. In addition, the submarine program is expected to generate meaningful employment opportunities across Taiwan and enhance the nation’s global competitiveness by demonstrating the ability to meet advanced military production standards, the suppliers suggested.

Furthermore, the statement described the project as a direct response to China’s efforts to block Taiwan’s defense advancement, portraying it as a breakthrough in countering such constraints. Lastly, the suppliers emphasized the need for transparency and integrity in the procurement process, warning against the interference of private interests in the selection of submarine contractors.


Challenges to the success of Taiwan’s IDS program

Despite the successful launch of the prototype, however, Taiwan faces significant challenges in building the planned seven additional submarines by 2038. 

According to Hsia, whether the prototype can be delivered on time is probably the most challenging task, especially since the prototype had to be developed entirely from scratch—a process that inevitably involves unanticipated complications.

Hsia said that given that safety standards cannot be compromised, delays in this initial delivery could derail the overall program timeline.

Admiral Chen, now a Kuomintang legislator, during the 2024 budget review, indicated that the current 14-year schedule to build seven submarines may prove overly optimistic. Chen said that by the fourth year, the first submarines will require regular maintenance and overhauls, even as new ones are still under construction.

With limited dry docks and manpower, CSBC could become overextended, and a more flexible production timeline would be helpful, Chen recommended.

The Ministry of National Defense (MND) has responded by confirming that it has developed dry dock scheduling solutions and implemented necessary security protocols to support sustained production and maintenance.

In addition, the complex challenge involves securing a steady supply of critical submarine components.

During a 2024 legislative session, Legislator Chen emphasized that natural disasters, supply chain disruptions, or sudden policy shifts in supplier countries could jeopardize component deliveries. He urged the MND to establish backup plans and alternative sourcing strategies to guard against program-wide vulnerabilities.

Hsia explained that IDS components fall into three categories: Red, Yellow, and Green.

Red Zone items—such as combat systems, diesel engines, torpedoes, and missile platforms—cannot be produced domestically and must be sourced through sensitive foreign partnerships. Yellow Zone items are difficult to obtain but could be locally developed with time and investment. Green Zone components are already within Taiwan’s production capacity.

Some Red Zone components are especially problematic due to their limited global availability. For example, photonics masts—a modern replacement for traditional periscopes—are manufactured by only a handful of companies worldwide.

Taiwan remains dependent on these suppliers. Hsia indicated that Taiwan must prepare not only for generic supply risks but also for targeted Chinese diplomatic pressure on supplier governments, which could halt exports and destabilize the entire IDS project.

Chairman Cheng also noted another challenge during a 2024 media interview. He said during COVID-19, many overseas suppliers halted operations, delaying deliveries. CSBC had to rapidly mobilize domestic suppliers to fill the gaps.

This episode highlighted that supply chain risks are not limited to geopolitical tension, but also extend to global events and other force majeure factors—making supply chain management in submarine production exceptionally demanding, Cheng added.


Taiwan’s IDS initiative is both a strategic necessity and a landmark achievement. It signals a historic moment for the ROCN’s defense self-reliance. After a century-long struggle, the ROCN is now closer than ever to realizing its ambition of building a credible and independent undersea deterrent. If fully executed, the IDS program will not only elevate Taiwan’s military readiness and resilience but also reinforce regional peace and stability in the face of growing maritime tensions.