Hanwha Ocean has officially launched the Republic of Korea Navy’s first KSS-III Batch-II attack submarine, the ROKS Jang Yeong-sil (SS-087), at its Geoje-si shipyard in Gyeongsang Province. The milestone marks a major leap forward in South Korea’s indigenous submarine production program, solidifying its position as a leading naval power in Asia. Senior government, military, and defense industry officials attended the launch ceremony.
Weighing 3,600 tons, the new submarine represents a next-generation evolution of South Korea’s undersea capabilities, designed to strengthen maritime security and bolster deterrence around the Korean Peninsula. The ROKS Jang Yeong-sil will undergo a series of trials and performance evaluations before officially joining the fleet in late 2027, as part of the Navy’s long-term effort to develop a self-reliant undersea warfare fleet.
Compared to the Batch-I KSS-III submarines, the Batch-II variant introduces lithium-ion battery technology, offering longer underwater endurance, higher cruising speeds, and improved stealth. The vessel’s upgraded sonar and combat management systems enhance target detection and engagement precision, while an auxiliary propulsion system ensures continued mobility even if the main propeller fails. Advanced noise and vibration suppression systems also make the submarine significantly harder to detect.
Constructed entirely with domestic technology and locally sourced components, the KSS-III Batch-II measures 89 meters in length, 10 meters in beam, and can reach speeds of 20 knots with a range exceeding 10,000 nautical miles. It is capable of remaining submerged for over 20 days, carrying a crew of around 50 personnel. Armed with submarine-launched ballistic and cruise missiles, the vessel provides South Korea with a powerful strategic deterrent. The Navy plans to operate nine KSS-III submarines by the 2030s, including three Batch-I vessels already commissioned between 2021 and 2024.
