Hai Kun Submarine

Taiwan's home-built deterrent — the Hai Kun ("Narwhal") is the island's first indigenously-built submarine, the product of a determined national program to do what Taiwan could not do on the open market: acquire modern submarines. Blocked for decades from buying boats abroad by Chinese diplomatic pressure, Taipei built its own — with quiet help from foreign engineers and suppliers — to field a stealthy, hard-to-find weapon that could threaten any Chinese fleet attempting a blockade or invasion. A fleet of up to eight is planned, making the Hai Kun a centrepiece of Taiwan's asymmetric defence.

Overview

The Hai Kun (hull number SS-711, also called the Indigenous Defense Submarine (IDS) or Narwhal) is Taiwan's first domestically-built submarine, constructed by CSBC Corporation. It is a conventional diesel-electric attack submarine of roughly 2,500–3,000 tonnes, around 70 m long, armed with heavyweight torpedoes and anti-ship missiles and fitted with modern sonar and a combat system. Its purpose is strategic and asymmetric: submarines are among the hardest weapons to detect and counter, and even a small force of capable boats could impose serious risk on a Chinese amphibious-invasion or blockade fleet, complicating Beijing's plans and strengthening deterrence. The Hai Kun's significance lies as much in that Taiwan built it at all as in the boat itself — overcoming the island's exclusion from the international submarine market through an indigenous program quietly assisted by foreign expertise.

Development

For decades Taiwan tried and failed to buy modern submarines abroad: Chinese pressure deterred potential sellers, leaving Taiwan's navy reliant on a handful of ageing boats (including two 1980s Dutch submarines and far older ex-US craft). Taipei therefore launched the Indigenous Defense Submarine program to build its own, with CSBC as prime contractor and quiet assistance from foreign engineers and suppliers across several countries, per Wikipedia and Naval News. (The program drew on foreign submarine know-how — including, controversially, former South Korean DSME designers, prompting a South Korean investigation into leaked design data.) The lead boat was launched in September 2023, underwent harbour acceptance testing through 2024, began sea trials in 2025, and completed its first submerged sea trial on 29 January 2026, per Naval News. Taiwan plans a fleet of up to eight such submarines. The program is a flagship of Taiwan's drive for self-reliant, asymmetric defence amid intensifying Chinese military pressure.

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