On September 28, Taiwan unveiled the first of its Hai Kun-class diesel-electric submarines. Constructed in a local shipyard in Kaohsiung with major foreign assistance, the Han Kun (officially dubbed the Narwhal in English) is planned to be the first of eight vessels that will join two existing 1980s-vintage ships in frontline service.
The new class is touted by the project’s leader as a key part of a strategy to prevent the invasion or blockade of the home islands. However, others see the Indigenous Defense Submarine (IDS) program, as it is officially known, as a poor use of scarce defense resources on a prestige project when simpler and more survivable systems would better serve Taiwan’s defense. As is often the case, the reality lies somewhere between these two positions.
Criticisms of the IDS project are ample and often justified. In recent years, there have been efforts to pivot Taiwan away from a traditional military posture centered upon large, expensive, and easily targeted platforms (such as combat aircraft, tanks, and conventional warships) and toward a more asymmetric strategy – typically defined as a form of warfare where the weaker side seeks to compensate for its shortfalls by targeting the enemy at its most vulnerable points. Such an approach is built upon a strategy and tactics that differ from those of the stronger opponent and typically utilizes large numbers of cheaper, smaller, shorter-range, and more survivable weapons systems.
The Rise and Stumble of the Overall Defense Concept
In 2017, the Taiwanese military leadership began an attempt to embed the asymmetric approach in the form of the Overall Defense Concept (ODC). For an all-out conflict over the fate of the main island, this envisaged a concept of operations that ensured force preservation during the initial wave of People’s Liberation Army (PLA) attacks followed by engagements using largely asymmetric systems in the littoral zone around Taiwan and enemy landing areas where the Chinese invading force would be at its most exposed. However, the ODC appears to have fallen out of favor as a result of institutional opposition, even though the United States has sought to pressure the government to focus on less gold-plated procurement projects.
Submarines sit in an awkward place on the symmetric-asymmetric spectrum. On the one hand, they are very large and expensive platforms that China possesses in far greater numbers, and it can be argued that the Republic of China Navy (ROCN) has sought to label them as asymmetric to justify the program. On the other hand, there is a credible case to be made that submarines are asymmetric given the degree of damage they can potentially inflict relative to the investment required and the effort an opponent must exert in countering them.
A leading argument against these vessels is that the resources used could have been better spent elsewhere on more purely asymmetric systems that are individually cheaper and more numerous. Notably, an ROCN program to build a $1.1 billion fleet of 60 small missile assault boats was scrapped in 2021 but could have been taken forward at less than the $1.54 billion price of the IDS program’s initial submarine. Additional examples of existing systems with asymmetric characteristics already in service with the ROC Armed Forces could also be purchased at a fraction of the initiative’s cost. More nebulous but potentially potent systems including uncrewed underwater vehicles and uncrewed surface vessels may also have benefited from more funding for their development.
However, as frustrating as it might be, it is not possible to dismiss institutional pressure for high-end systems out of hand. Procurement sits within the realm of what is politically possible. It is also hardly a uniquely Taiwanese problem: The United States would arguably be able to generate more effective and survivable combat power if it pivoted some of the funding for traditional platforms such as the F-35 toward less politically well-supported alternatives including ground-launched conventional missiles, but vested interests and institutional inertia prevent this.
There is also the fallacy that had resources not been expended in one particular way they would have automatically been used in another, more desirable one. Such decisions are not so straightforward in the real world. It is political will, rather than money, that is the constraining factor.
It would, therefore, be a mistake to see this as an either/or issue. Taipei has both significantly increased its (admittedly still low in the circumstances) defense spending and invested in lower-end asymmetric capabilities. Purchases of submarines, F-16V combat aircraft, and M-1A2T tanks have occurred alongside acquiring truck-launched Harpoon anti-ship missiles, Volcano mine deployment systems, and Chien Hsiang loitering munitions, to name but a few recent procurement decisions, while production rates of Hsiung Feng II and Hsiung Feng III anti-ship missiles and Tien Kung III surface-to-air missiles are being ramped up.
Strengths and Weaknesses
The military arguments against Taiwan’s investment in a new submarine fleet are substantial. Even when all eight vessels are built, they will be vastly outnumbered by their PLA Navy equivalents and face being smothered by Beijing’s wider anti-submarine warfare capability. Submarines are also highly vulnerable when in port – as Russia’s recent effective loss of a Kilo-class submarine in Sevastopol to Ukrainian cruise missiles underlined – and even when absent, their support facilities are easily targetable. This eliminates the potential for Taipei to mount any form of independent sustained submarine campaign.
Despite this, experience shows that diesel-electric submarines can force much larger and more capable fleets to expend major effort in countering them. During the 1982 Falklands War, the Royal Navy never managed to sink the Argentine submarine ARA San Luis despite extensive anti-submarine warfare (ASW) patrols and munitions expenditure, although the British were admittedly primarily trained and equipped to hunt noisy Soviet nuclear-powered submarines rather than quieter conventional vessels. The United States also had a sobering experience when one of its carriers was “sunk” during a training exercise with the Swedish Navy, notwithstanding that the conventionally powered submarine in question had an air-independent propulsion system that Taiwanese vessels will for the moment apparently lack.
The peacetime vulnerability of Taipei’s submarine force in home ports could to some extent be mitigated by a sustained program of patrols ensuring two or three were always at sea. The requirement for preparation for an attack also makes a “bolt-from-the-blue” strike by the PLA difficult to carry out, and such early warning could allow for additional submarines to deploy. The sustainability of the force in an all-out conflict is a more intractable problem given the near-inevitable destruction, blockade, or even capture of Taiwan’s ports, but making pre-war arrangements for any submarines that survived their initial encounters with Beijing’s forces to fall back to U.S. or Japanese bases to resupply could help mitigate this.
Wartime operations by the submarines could include reconnaissance, sinking surface ships and submarines, minelaying, and special forces support. Nevertheless, it remains the case that in the event of an all-out attempt to capture Taiwan, it would be the U.S. Navy and potentially the Japanese Maritime Self-Defense Force that would be the main allied players under the sea. Just as Estonia has its NATO partners provide combat aircraft for its defense so it can focus on its ground forces, it may be best for the ROC Armed Forces to specialize by providing the type of local capability centered on immediate territorial defense that its allies cannot supply quickly.
The main counter to this argument is that there is significant value in a submarine force beyond wartime taskings. In peacetime, they can provide sustained intelligence on PLA forces in the region while being less susceptible to interference than drones owing to the higher escalation risk of attacking crewed vessels. In contingencies less serious than an all-out invasion attempt, they also complicate China’s risk calculus. Removing the threat of submarine attack would simplify the mission of a PLA force seeking to accomplish limited goals such as the capture of Taiwan’s offshore islands or territory in the South China Sea.
A Matter of Time
Perhaps the most potent case against the IDS program is one of timescale. The future ROCS Hai Kun still has to undergo further fitting out and testing, with delivery occurring before the end of 2024 if everything goes to plan. The second vessel is due in 2027, with the timetable for the remaining six uncertain.
Much has been made of China’s reported intention to be ready to invade Taiwan by 2027. While the relevance of this is disputable – simply having a capability does not necessarily result in action – it does suggest that the IDS program may not deliver what it promises with sufficient haste. Even should the fleet become fully operational, it may be that the PLA’s ASW capability will in the foreseeable future advance to the point that any type of large submarine operations near China’s coastline are impossible.
Blanket dismissal of the value of Taiwan’s new submarines is unwarranted, and they are likely to make a useful medium-term contribution to the defense of Taiwan They are also not the overwhelming drain on the wider, necessary, and still far from complete pivot toward less costly asymmetric systems some depict them as. Nevertheless, they will only be one small component in the international military force that needs to maintain deterrence and if necessary, prevail in conflict.