Taiwan Builds Its Own Submarines: The Indigenous Defense Submarine Program and What It Means
Taiwan launched its first indigenously designed and built submarine in September 2023. The vessel — named Hai Kun, or Narwhal — represented the culmination of a program that was announced in 2016, funded against significant domestic political opposition, and executed despite the near-total unavailability of normal defense industrial cooperation channels. No major submarine-building nation would sell Taiwan a complete submarine. The United States, which provides most of Taiwan’s conventional weapons, does not export submarines to any partner. Taiwan built one anyway, with foreign assistance obtained through channels that required deliberate diplomatic ambiguity from the governments whose citizens and companies were involved.
The strategic logic of the submarine program is compelling even if the path to executing it was tortured. Taiwan’s surface navy — a force of destroyers, frigates, and corvettes — operates in waters where PLA naval and air forces have achieved a capacity to threaten surface combatants throughout the strait. Surface ships are visible, trackable, and increasingly vulnerable to the anti-ship missile systems that the PLA has invested in heavily. Submarines are not. A conventionally powered submarine, operated quietly in the approaches to the strait or in the Philippine Sea east of Taiwan, presents a threat to PLA amphibious shipping and surface combatants that is difficult to neutralize without ASW forces that the PLA, while improving, has not fully developed.
The capability of the Hai Kun relative to the submarines operated by the PLA Navy and by allied navies is a subject of informed speculation rather than confirmed public assessment. Taiwan has obtained design assistance and components from multiple foreign sources, including, according to reporting, American firms providing combat systems, European companies providing certain subsystems, and Indian and other assistance channels. The resulting vessel is not a copy of any existing design and reflects Taiwan’s specific operational requirements — relatively shallow water operations in the strait and its approaches, emphasis on anti-ship rather than anti-submarine or land-attack missions, and compatibility with the weapons and sensors Taiwan can obtain.
The program’s trajectory beyond the first hull is the key question. A single submarine is a demonstration and a training vessel more than it is an operational capability. Taiwan has announced plans to build additional hulls, with the goal of a fleet of eight submarines total. The production timeline depends on funding — which requires sustained political commitment through legislative cycles that have not always been sympathetic to submarine spending — and on the availability of key components that must be obtained through channels that remain diplomatically sensitive.
The operational concept for Taiwan’s submarine force centers on the role submarines can play in a blockade or invasion scenario that surface forces cannot. Submarines positioned east of Taiwan in the Philippine Sea can threaten PLA naval forces attempting to encircle the island from the Pacific side. Submarines positioned in the strait approaches can threaten amphibious shipping during the crossing phase. The threat does not require the submarines to achieve high kill rates — it requires the PLA to devote ASW resources to finding and tracking them, resources that are thereby unavailable for other missions, and to route amphibious forces on paths that account for submarine threat envelopes, adding time and exposure to the crossing.
The foreign assistance dimension of the program deserves more sustained public acknowledgment than it has received. The governments and companies that helped Taiwan build a submarine did so in a context where that assistance could not be formally admitted. The individuals who traveled to Taiwan to provide design and technical expertise were doing so with the awareness of their own governments, which had made a calculation that Taiwan’s submarine capability served interests that those governments were not able to pursue through official channels. The diplomatic architecture of the Taiwan relationship is full of arrangements that work precisely because they are not described accurately in public.
Taiwan has a submarine now. The strait has a different threat environment than it did before. The two facts are connected.