Taiwan Hai Kun Submarine Fires First Torpedo Validating Combat System Against Chinese Navy Threats.

Taiwan’s first domestically built Hai Kun (SS-711) diesel-electric attack submarine has completed a torpedo-firing exercise, validating its underwater combat system, including detection, fire-control calculations, launch, and torpedo guidance. The milestone moves Taiwan closer to fielding a submarine capable of threatening Chinese Navy amphibious ships, escorts, and submarines during a blockade or potential Chinese invasion.

Taiwan’s Military News Agency reported on May 13, 2026, that the test successfully demonstrated Hai Kun’s detection, calculation, launch, and torpedo-guidance functions during sea trials. The event marks a major step up from earlier propulsion, sonar, and diving evaluations toward proving the combat sequence needed to engage an enemy vessel underwater.

Related Topic: Taiwan’s First Indigenous Hai Kun SS-711 Submarine Completes Sixth Sea Trial

Taiwan’s Hai Kun (SS-711), the country’s first domestically built attack submarine, is progressing through combat-system trials as Taipei develops a new undersea capability to threaten PLA Navy amphibious and escort forces during a potential conflict. (Picture source: Taiwan Media)

The U.S. weapons connection gives the milestone additional operational weight. In May 2020, the U.S. State Department approved a possible $180 million Foreign Military Sale to Taiwan covering 18 Mk 48 Mod 6 Advanced Technology heavyweight torpedoes and associated equipment. Designed to engage both surface vessels and submarines, the Mk 48 Mod 6 gives Taiwan a modern underwater strike capability directly relevant to countering PLA Navy warships and amphibious forces.

For Hai Kun, the importance of the exercise lies in validating far more than the mechanical operation of a torpedo tube. A submarine must first detect and classify a contact through its sonar suite, calculate the target’s movement using its combat-management and fire-control systems, prepare a firing solution, initialize the weapon, and then launch and guide the torpedo. Demonstrating those functions as an integrated chain is a prerequisite for turning the submarine’s underwater stealth into actual combat power.

The consequence is especially relevant to a Chinese amphibious assault. Any major Chinese operation against Taiwan would depend on moving troops, armored vehicles, ammunition, and supplies across surrounding waters aboard amphibious assault ships, landing vessels, and transports protected by destroyers, frigates, helicopters, and maritime patrol aircraft. A submarine capable of remaining concealed near likely transit routes and attacking with heavyweight torpedoes would force the Chinese Navy to dedicate substantial resources to anti-submarine warfare before those ships could safely approach the island.

Hai Kun is a conventionally powered attack submarine with an estimated submerged displacement in the 2,500- to 3,000-ton range. Public reporting indicates that it uses diesel generators to recharge battery banks for quiet electric propulsion underwater and incorporates an X-shaped stern control arrangement intended to improve submerged handling. Taiwan, however, has kept many detailed performance characteristics classified.

Its propulsion arrangement supports the sea-denial role Taiwan expects the submarine to perform. At low speed on battery power, a diesel-electric submarine can reduce machinery noise and complicate detection by Chinese anti-submarine warfare vessels and aircraft. However, the absence of a confirmed air-independent propulsion system means that Hai Kun must periodically recharge its batteries, creating an important endurance constraint.

Sensor performance is equally critical. Earlier Hai Kun trials included sonar calibration, hull-integrity checks, velocity control, and submerged maneuvering, with reports describing bow-mounted and flank sonar arrays optimized for passive underwater detection. Passive sonar allows the submarine to listen for the acoustic signatures of hostile ships without transmitting an active signal that could reveal its own location, supporting an ambush-oriented concept of operations around Taiwan’s maritime approaches.

That concept fits Taiwan’s geography and force structure. Hai Kun does not need to pursue the much larger Chinese Navy across the western Pacific to have military value; instead, it can patrol likely maritime approaches, monitor Chinese naval movements, and wait for high-value vessels to enter favorable firing positions. In a wartime scenario, those targets could include amphibious assault ships, landing vessels, and escorts supporting an invasion force, as well as Chinese submarines attempting to operate around the island.

Taiwan plans to arm its indigenous submarine force with U.S.-supplied Mk 48 Mod 6 Advanced Technology heavyweight torpedoes, giving Hai Kun a weapon capable of engaging both surface warships and submarines to support Taiwan’s sea-denial strategy. (Picture source: U.S. Department of War/Defense)

The Mk 48 Mod 6 is central to this combat role. The U.S.-approved package gives Taiwan access to a modern heavyweight torpedo specifically intended for both anti-surface and anti-submarine warfare, creating a weapon pairing suited to Hai Kun’s mission of remaining concealed while threatening major surface formations and hostile submarines.

The latest firing therefore represents an important transition in Hai Kun’s test program. On February 16, 2026, the submarine completed its sixth sea trial off Kaohsiung, during which Taiwan evaluated sonar calibration, propulsion response, hull integrity, and shallow-water handling ahead of deeper submerged testing. The torpedo exercise subsequently demonstrated that development had advanced from proving that the submarine could operate safely underwater to verifying elements of the combat system used to attack a target.

Hai Kun is also significant because Taiwan intends it to establish the foundation for a larger indigenous submarine force. Army Recognition previously reported a long-term objective of eight new domestically produced submarines, which would operate alongside the two Dutch-built Hai Lung-class boats that have formed the backbone of Taiwan’s frontline submarine capability for decades.

Taiwan’s effort to develop submarines domestically is closely tied to the difficulties it has faced in obtaining complete modern submarines from foreign suppliers. The Indigenous Defense Submarine program consequently places CSBC Corporation at the center of pressure-hull construction, submarine assembly, equipment installation, integration, and testing, while selected foreign technologies remain important for sensors, combat systems, and weapons.

The industrial benefit extends beyond Hai Kun itself. Continued domestic construction would allow Taiwanese engineers and shipyard workers to retain specialist knowledge in pressure-hull fabrication, acoustic management, propulsion integration, and combat-system installation, while enabling lessons learned from the prototype to be incorporated into subsequent submarines. Army Recognition reported in 2025 that Taiwan was preparing follow-on construction under a phased production approach intended to expand the indigenous force.

Related Army Recognition coverage of Hai Kun’s sea-trial program has followed the submarine’s progression from harbor and propulsion testing toward submerged operations. The torpedo firing is the first clear indication that those trials are now validating the systems required for actual underwater combat.

Against China, the operational value of a larger submarine force would derive from uncertainty rather than numerical parity. A relatively small number of modern submarines dispersed around Taiwan could force the Chinese Navy to allocate destroyers, frigates, helicopters, patrol aircraft, and underwater sensors to searching for them, reducing the forces available for other missions during a blockade or amphibious assault.

That burden would matter even more during an invasion attempt. Amphibious ships carrying troops and vehicles are critical to sustaining a landing operation, and any uncertainty over submarine activity could compel Chinese commanders to slow formations, widen escort screens, alter transit routes, or delay movement until likely submarine operating areas had been searched.

Hai Kun could also threaten the warships conducting those searches. The same destroyers and frigates protecting Chinese amphibious vessels would themselves remain potential torpedo targets, forcing escorts to balance aggressive anti-submarine warfare with the need to remain close enough to protect the troop-carrying ships at the center of the formation.

Submarines would also play a role during a blockade. Chinese naval and coast guard forces attempting to isolate Taiwan would have to maintain positions in, or repeatedly enter, predictable operating areas near major ports and maritime approaches. This pattern could create opportunities for submarines to exploit concealed patrol positions and force Beijing to maintain continuous anti-submarine protection.

Army Recognition coverage of Taiwan’s indigenous submarine development has also detailed plans for follow-on submarines derived from Hai Kun. Expanding the force would matter operationally because some boats will always be unavailable because of maintenance, crew training, or modernization, while additional submarines would allow Taiwan to maintain more persistent patrol coverage.

Hai Kun is not yet a fully operational combat submarine. Taiwan continues to conduct testing and system verification, and the prototype must complete the remaining acceptance process before entering regular naval service. The May torpedo exercise nevertheless represents a considerably more significant capability milestone than earlier surface or propulsion trials because it directly tested the functions required for combat.

The event also demonstrates how Taiwan’s indigenous submarine program and U.S. weapons support are converging. Domestic construction gives Taipei greater control over the hull, integration process, maintenance base, and future fleet expansion, while the Mk 48 Mod 6 provides the modern heavyweight weapon needed to translate that industrial achievement into an operational anti-ship and anti-submarine capability.

For the Chinese Navy, the significance is straightforward: Hai Kun is progressing toward becoming a concealed underwater threat that Chinese planners would have to account for in any operation around Taiwan. If Taiwan succeeds in moving from the prototype to a larger force of indigenous submarines armed with Mk 48 Mod 6 torpedoes, Chinese amphibious assault ships and their escorts would face an additional attack threat along the maritime routes any invasion would depend on.

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Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.