Indonesia Tests Indigenous KSOT Autonomous Submarine with ‘Piranha’ Torpedo

On October 30, 2025, PT PAL Indonesia, the country’s leading state-owned shipbuilder, successfully conducted a torpedo firing test of its prototype autonomous submarine, known domestically as KSOT (Kapal Selam Otomatis Tanpa Awak). The test took place in Surabaya, East Java, marking a historic milestone in Indonesia’s pursuit of indigenous underwater defense technologies.

According to PT PAL, this autonomous submarine represents Indonesia’s first domestically designed and built unmanned underwater vehicle (UUV) capable of carrying and launching live torpedoes. The demonstration is a significant indicator of the nation’s growing industrial and technological independence in the maritime defense sector.

The Test: A Step Toward Operational Readiness

The torpedo firing event began with the loading of a 324 mm lightweight ‘Piranha’ torpedo, reportedly developed by PT PAL itself. Using a mobile crane at the Indonesian Navy’s (TNI AL) 2nd Fleet Command pier, the torpedo was carefully mounted into the starboard-side launch tube attached externally to the KSOT.

Once the loading was complete, the autonomous submarine was released into deeper waters to perform its first live-fire demonstration. Video footage released by PT PAL shows the KSOT diving, maneuvering, and launching the torpedo, with the system remaining partially submerged during most of the test sequence.

The successful firing verified the KSOT’s ability to integrate, control, and deploy live ordnance autonomously — a key benchmark in transforming the prototype into an operational weapon platform.

KSOT Specifications and Design

The KSOT prototype unveiled during the 80th Anniversary Parade of the Indonesian National Armed Forces (TNI) on October 5, 2025, features a length of 15 meters, a beam of 2.2 meters, and a draught of 1.85 meters. It can reach a maximum submerged speed of 20 knots and operate at depths of up to 350 meters, making it suitable for both coastal and deep-water operations.

While detailed internal configurations remain classified, the KSOT reportedly houses:

• Electric propulsion system powered by high-capacity lithium-ion batteries.

• Autonomous navigation and control software developed domestically by Indonesian engineers.

• Sonar and sensor arrays for underwater terrain mapping and target tracking.

• External payload mountings, including a single 324 mm torpedo tube (as tested).

The KSOT is designed for modular configuration, allowing it to perform diverse missions such as intelligence, surveillance, reconnaissance (ISR), mine detection, decoy operations, and potentially kamikaze missions against surface or underwater threats.

‘Piranha’ Lightweight Torpedo: Indonesia’s Indigenous Firepower

The ‘Piranha’ lightweight torpedo, developed by PT PAL, is a 324 mm-class weapon system optimized for use against submarines and surface vessels. Although detailed technical data is not publicly disclosed, analysts suggest it may feature:

• A range of 10–15 kilometers.

• Active/passive acoustic homing guidance.

• High-explosive warhead suitable for light-to-medium target engagement.

• Electric propulsion, reducing noise signature for stealth operations.

The torpedo’s successful integration with the KSOT highlights Indonesia’s increasing capability to produce both platforms and weapon systems domestically.

Domestic Innovation and Future Production

PT PAL emphasized that the KSOT is fully designed and developed by Indonesian engineers, with a local component content exceeding 50%. The company aims to further increase this percentage through partnerships with domestic suppliers and research institutions.

The KSOT incorporates commercial off-the-shelf (COTS) components, a strategic approach that balances cost efficiency with adaptability. PT PAL stated that experience gained from this project would support the future development of autonomous naval systems, including unmanned surface vessels (USVs) and hybrid underwater drones.

Deployment Plan: 30 Units by 2026

According to the Indonesian Ministry of Defence (MoD), 30 KSOT units are scheduled to enter service by 2026 under the Indonesian Navy’s Submarine Operations Command (Koopskasel). These units will be deployed across key maritime choke points such as the Lombok and Sunda Straits, where strategic surveillance and deterrence are critical.

It is not yet confirmed whether all 30 KSOTs will be equipped with torpedo-launching capabilities, as the program also envisions non-lethal variants designed for ISR, mine warfare, or decoy operations.

Given its compact dimensions and modular design, the KSOT can also be launched from larger surface vessels, including amphibious ships or future Indonesian frigates, providing the Navy with an extended operational reach.

Official Endorsement and Next Steps

The live-fire test was attended by Defence Minister Sjafrie Sjamsoeddin, Navy Chief of Staff Admiral Muhammad Ali, and senior naval officers. Minister Sjamsoeddin lauded PT PAL’s efforts, describing the test as “a strategic leap toward achieving full autonomy in underwater warfare technology.”

He added that the KSOT will continue to undergo evaluation, endurance trials, and software upgrades before mass production begins. PT PAL has also hinted at future larger variants with enhanced payload capacity and longer endurance, potentially integrating with Indonesia’s future anti-submarine warfare network.

Strategic Significance

Indonesia’s KSOT program marks a critical evolution in Southeast Asia’s defense landscape. As maritime tensions rise in regional waters, the ability to deploy autonomous submarines offers Indonesia a low-cost, persistent, and stealthy surveillance option across its vast archipelagic zones.

By combining indigenous design, scalable production, and modular flexibility, PT PAL’s KSOT initiative underscores Indonesia’s ambition to become a leading regional hub for autonomous naval technologies — strengthening not only its defense posture but also its national technological independence.