Hanwha Ocean has officially launched the Republic of Korea Navy’s (ROKN) first Dosan Ahn Chang-ho-class (KSS-III) Batch-II attack submarine, marking a significant milestone in South Korea’s drive to independently design, build, and operate advanced undersea vessels. The ROKS Jang Yeong-sil (SS-087) was inaugurated at Hanwha’s shipyard in Geoje-si, Gyeongsang Province, with top military and defense officials in attendance.
The 3,600-ton diesel-electric submarine reflects Seoul’s commitment to strengthening maritime security amid rising regional tensions in East Asia. The vessel is expected to enhance South Korea’s ability to monitor, deter, and, if necessary, respond to threats across the Korean Peninsula and surrounding seas. The navy plans to conduct rigorous testing and evaluation before formally commissioning the submarine into service in late 2027.
Advanced Power, Stealth, and Range
Compared to its KSS-III Batch-I predecessors, the Jang Yeong-sil offers substantial improvements in operational endurance and survivability. A key upgrade is its lithium-ion battery system, which allows the submarine to remain submerged longer, operate at higher speeds, and reduce the likelihood of detection by enemy forces.
The vessel’s advanced sonar and combat systems provide more precise tracking and targeting of both surface ships and land targets. Its auxiliary propulsion system ensures the submarine can maneuver even if the main propeller becomes disabled, significantly enhancing safety during extended missions. Additionally, integrated noise and vibration reduction technologies improve stealth capabilities, making it more difficult for adversaries to detect the submarine in contested waters.
Specifications and Capabilities
The KSS-III Batch-II submarine, built entirely with domestic South Korean technology and components, measures 89 meters (292 feet) in length with a 10-meter (33-foot) beam. The vessel can reach speeds of up to 20 knots (37 km/h; 23 mph) and operate continuously for approximately 10,000 nautical miles (18,520 km; 11,508 mi) without surfacing. These capabilities enable missions lasting more than 20 days underwater, providing the navy with persistent and flexible undersea operations.
The submarine carries a crew of around 50 personnel and is armed with a versatile weapons suite, including submarine-launched ballistic missiles (SLBMs) and land-attack cruise missiles (LACMs). This armament significantly strengthens South Korea’s undersea strike and deterrence capabilities, particularly in the context of regional security challenges posed by North Korea and other potential adversaries.
Strategic Implications
The launch of the ROKS Jang Yeong-sil underscores South Korea’s ambition to maintain a technologically sophisticated undersea fleet, reducing reliance on foreign defense systems while advancing indigenous naval innovation. Seoul plans to commission a total of up to nine KSS-III submarines through the 2030s, with three Batch-I units already integrated into the fleet between 2021 and 2024.
With the Batch-II variant, the Republic of Korea Navy not only increases its underwater operational reach but also demonstrates the growing maturity of South Korea’s defense-industrial base. The combination of extended endurance, stealth technologies, and strategic missile capabilities positions the KSS-III Batch-II as a cornerstone of South Korea’s modern naval deterrence strategy, capable of addressing both conventional and emerging maritime threats.
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