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Japan and Indonesia Boost Naval Power with Advanced Submarine Fleets

From stealthy Taigei-class giants to compact DGK-class subs, Asia's underwater arms race heats up. Who's leading—and why South Korea wants nuclear power?

,   and  Administrator
2 min read
The image shows a group of people standing on top of a submarine in the water, with a boat in the...
The image shows a group of people standing on top of a submarine in the water, with a boat in the background. The sky is visible at the top of the image, and there are buildings and trees in the distance. This image is likely related to the news that the US Navy has announced that it will be launching a nuclear-powered submarine.

Japan and Indonesia Boost Naval Power with Advanced Submarine Fleets

Japan and Indonesia have expanded their submarine fleets with new advanced vessels. Japan recently commissioned its fifth next-generation Taigei-class submarine, while Indonesia finalised a deal with Italy for six compact DGK-class submarines. Both moves highlight ongoing modernisation efforts in naval defence across Asia.

Meanwhile, South Korea continues to push for nuclear-powered submarine capabilities, though no broader global trend towards such vessels has emerged in recent years. Japan's latest submarine, the JS Chōgei (SS-517), entered service as part of the Taigei-class fleet. This class features enhanced stealth, advanced detection systems, and a crew of around 70 personnel. Each vessel measures 84 metres long, with a standard displacement of 3,000 tons, and is equipped with the ZQQ-8 sonar suite, Kai-1 optronic masts, and Type 18 torpedoes. The submarines also carry UGM-84L Harpoon Block II anti-ship missiles and a new combat management system.

The lead Taigei submarine was commissioned in March 2022, and the sixth, Sōgei (SS-518), is set to join the fleet in March 2027. Japan's 2026 defence budget includes ¥120.8 billion ($766 million) for the construction of the tenth Taigei-class submarine, reinforcing its long-term commitment to underwater defence.

Indonesia has signed a billion-dollar agreement with Italy for six DGK-class compact submarines. The first two vessels are estimated to cost $480 million. These submarines measure 34 metres in length, with a surface displacement of 219 tons and a maximum submerged speed of 15 knots. The deal also includes the transfer of an Italian aircraft carrier as part of a broader defence package.

South Korea remains the only country in the region actively seeking nuclear-powered submarine technology. Its push comes in response to North Korea's nuclear threats, though no other nations have publicly pursued similar programmes in recent years. Global demand for nuclear-powered submarines has not shown a clear upward trend between 2021 and 2026. Japan's Taigei-class and Indonesia's DGK-class submarines represent significant upgrades in naval capabilities. The new vessels bring improved stealth, detection, and combat systems to their respective fleets. South Korea's interest in nuclear-powered submarines remains an exception rather than part of a wider global shift. No other countries have publicly announced plans to develop such technology in the past five years.

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