South Korea launches third Chungnam-class frigate ROKS Jeonnam to guard national waters.

South Korea launched the third Chungnam-class frigate, ROKS Jeonnam, at SK Oceanplant’s Goseong shipyard on November 25, 2025.

On November 25, 2025, the South Korean Navy launched the third Ulsan-class Batch-III (Chungnam-class) frigate, the ROKS Jeonnam (FFG-831), at SK Oceanplant’s shipyard in Goseong, South Gyeongsang Province. The 3,600-ton ship will complete outfitting and trials through late 2026, before entering operational evaluation and joining the fleet as part of a broader replacement cycle for older Ulsan- and Pohang-class ships. Equipped with the Korean Vertical Launching System (KVLS) and a range of guided missiles, the Jeonnam will be used for air defense, surface warfare, land attack, and anti-submarine tasks across coastal and regional waters.
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The Future Frigate eXperimental (FFX) program was conceived to replace aging Ulsan-class frigates, Pohang-class corvettes, and some earlier destroyers to provide a force of roughly 26 modern frigates across several batches. (Picture source: South Korean Navy)

The launch ceremony for the ROKS Jeonnam was organized jointly by the South Korean Navy and the Defense Acquisition Program Administration (DAPA) and brought together about 150 guests at SK Oceanplant in Goseong. Attendees included National Assembly Defense Committee Chairman Sung Il-jong as principal guest, Chief of Naval Operations Admiral Kang Dong-gil, DAPA Deputy Minister Kang Hwan-seok, SK Oceanplant CEO Lee Seung-cheol, and multiple officials from the Navy, the acquisition authority, and the shipbuilder. The program included a briefing on the ship, the formal name proclamation, congratulatory remarks, and a safe-voyage ceremony consistent with established naval practice. In accordance with custom, Chairman Sung’s spouse, Im Sun-hee, cut the ceremonial launching rope attached to the bow, symbolically separating the ship from the construction phase and marking its transition toward operational life. After the rope cutting, dignitaries jointly cut multicolored ribbons and broke a champagne bottle against the hull as part of the traditional blessing procedure.

In his speech, Chairman Sung linked the ROKS Jeonnam and the contemporary fleet to historical ships such as Turtle Ships and PC-701 Baekdusan, emphasizing continuity in maritime defense roles. He also stated that the introduction of new frigates supports ship design and construction competencies, strengthens export competitiveness, and contributes to economic activity through domestic shipbuilding and systems integration. The ROKS Jeonnam (FFG-831) belongs to the Chungnam-class, also confusingly referred to as Ulsan-class Batch-III or FFX Batch-III, which is based on the preceding Daegu-class that itself evolved from the Incheon-class. The Chungnam-class incorporates domestically developed combat systems and sensors, including a composite integrated sensor mast and a fixed multifunction phased array radar, reflecting a policy of increasing national industrial participation in core systems. Following its launch, the ROKS Jeonnam will complete outfitting, harbor trials, and sea trials before scheduled delivery to the Navy in December 2026 and subsequent operational evaluation.

Once this process is concluded, the frigate is planned to enter front-line service as part of the wider surface combatant renewal plan. The frigate follows the convention of naming ships after cities and provinces, in this case Jeollanam-do, and reuses the Jeonnam name previously assigned to earlier Korean warships that have now left active service. The frigate has an approximate standard displacement of 3,600 tons and a full-load displacement of around 4,300 tons, with dimensions of about 129 meters in length, 14.8 meters in beam, and a draft of 4.2 meters, and an overall height of roughly 38.9 meters. The ship’s crew complement is generally cited in the 120 to 125 personnel range, reflecting South Korea's choice to reduce manning compared to earlier Ulsan-class units. Maximum speed is around 30 knots, with cruising speeds around 15 to 18 knots and an endurance of about 4,500 nautical miles, to support patrol, escort, and area surveillance missions in waters surrounding the Korean Peninsula and adjacent sea lanes.

The hull and superstructure continue the stealth-influenced features introduced with the Incheon- and Daegu- classes, with angled surfaces and integrated masts intended to reduce radar cross section compared to older frigates. Publicly available information indicates that the Chungnam-class can track and engage several incoming missiles simultaneously, with some references mentioning the ability to respond to up to eight aerial threats at once, depending on fire-control integration. Within the overall FFX program, the class represents a shift from relatively simple coastal frigates toward multi-mission frigates with more comprehensive air defense and anti-submarine capabilities. The South Korean-designed combat system on the ROKS Jeonnam is centered on a composite integrated sensor mast that houses a four-faced fixed, multifunction, active electronically scanned array radar. This radar provides continuous 360-degree coverage without mechanical rotation, permitting the simultaneous detection, tracking, and engagement support against air and surface targets, marking a progression from the rotating SPS-550K radars fitted to the Incheon- and Daegu- classes.

The mast also incorporates an infrared search and track system, electro-optical tracking equipment such as the SAQ-560K, and the K/SPS-95K surface search and navigation radar, bringing multiple sensors into a single structure to simplify integration and signature control. A Hanwha Systems combat management system, often described as Baseline 3.0, fuses inputs from the multifunction radar, IRST, electro-optical systems, sonar, and external networks to produce a combined tactical picture and coordinate engagements, with the ability to manage responses against more than ten aerial targets concurrently. Electronic warfare equipment includes the SLQ-200K Sonata suite, which provides electronic support measures and countermeasures, and the SLQ-261 torpedo decoy system, combined with Rheinmetall's MASS decoy launchers to dispense chaff and flares for soft-kill defense. Underwater sensors consist of the SQS-240K hull-mounted active/passive sonar and the SQR-250K towed array sonar system, which together support the detection and tracking of submarines and torpedoes at different ranges and depths. These sensor and combat system arrangements position the Chungnam-class as a key element in South Korea’s effort to field frigates with more integrated air defense, surface, and anti-submarine functions than previous mid-sized surface combatants.

The ROKS Jeonnam’s armament suite follows the standard Chungnam-class configuration and provides a mix of systems intended to support surface, air defense, land-attack, and anti-submarine missions. (Picture source: South Korean Navy)

Forward, the frigate carries a 127 mm, 62-caliber, Mk 45 Mod 4 naval gun produced under license by Hyundai WIA, which can be used for naval gunfire support, surface engagements, and basic air-defense firing when appropriate. Close-in defense against missiles and aircraft is provided by a single CIWS-II system, which is installed in the usual aft superstructure position on other ships of the class. The main missile battery is a 16-cell Korean Vertical Launching System (KVLS) that can carry Haegung K-SAAM surface-to-air missiles (quad-packed in individual cells), Haeryong vertical-launch tactical land-attack missiles, and K-745 Red Shark anti-submarine rockets, giving the ship a combination of medium-range air defense, strike, and standoff anti-submarine options. In addition to these vertical-launched weapons, the frigate carries eight SSM-700K Haeseong (C-Star) anti-ship missiles in canister launchers for over-the-horizon surface warfare, with some references also noting inclined-launch variants of tactical land-attack missiles that could be integrated with this arrangement.

Two triple 324 mm KMk 32 torpedo tubes provide launch capability for K745 Blue Shark lightweight torpedoes used for close-in anti-submarine engagements, and the ship may also employ small depth charges where appropriate. Aviation facilities include a flight deck and enclosed hangar sized for one medium helicopter, such as the AW159 Wildcat or a Westland Super Lynx, which extends the ship’s reach for anti-submarine, surveillance, and surface-strike missions. Earlier expectations in public debate that the class might field a new long-range area air defense missile, sometimes compared to an indigenous SM-6, have not been reflected in confirmed armament descriptions, which instead emphasize the established K-SAAM, Red Shark, and land-attack missile family. The propulsion system on ROKS Jeonnam uses a combined diesel-electric or gas (CODLOG) configuration designed to reduce underwater radiated noise while maintaining the ability to reach higher speeds when required. The arrangement consists of one Rolls-Royce MT30 gas turbine for high-speed operations, four MTU 12V 4000 M43B diesel generator sets that supply electrical power, and two Leonardo DRS permanent-magnet electric motors driving two controllable-pitch propellers through twin shafts.

In typical patrol or anti-submarine missions, the frigate can operate primarily in diesel-electric mode with the gas turbine shut down, which reduces acoustic output and supports the performance of the hull-mounted and towed-array sonars. When higher speeds are needed for interception, maneuvering, or repositioning, the MT30 turbine is engaged to provide enough power for speeds around 30 knots, while cruising speeds around 15 to 18 knots are used to optimize fuel consumption and endurance. This propulsion approach develops the CODLOG solution introduced on the Daegu-class frigates, which were the first Korean warships to combine an electric drive and a single gas turbine at this displacement. In the broader context of the FFX program, the Incheon-class (Batch I) introduced stealth shaping and established the baseline multi-role frigate concept, the Daegu-class (Batch II) added CODLOG propulsion, towed-array sonar, and the first Korean Vertical Launching System on medium frigates, and the Chungnam-class (Batch III) now adds fixed multifunction AESA radar and an integrated sensor mast as the next step in the series. 

The Future Frigate eXperimental (FFX) program was conceived to replace aging Ulsan-class frigates, Pohang-class corvettes, and some earlier destroyers to provide a force of roughly 26 modern frigates across several batches. Initial long-term requirements for a new coastal frigate were raised in the late 1990s, and after delays linked to economic conditions, the concept re-emerged in the early 2000s under the FFX label. Hyundai Heavy Industries received the basic design contract for what became the Incheon-class, with the lead ship launched in April 2011 and commissioned in January 2013, followed by five additional units through 2016; these ships displace about 2,500 tons empty and 3,300 tons full, providing the first step in replacing Ulsan- and Pohang-class units. The eight Daegu-class (Batch II) ships, launched between 2016 and 2022, followed as an improved Incheon derivative with increased displacement to around 3,600 tons full load, an enlarged hangar and flight deck, TB-250K towed-array sonar, 16-cell K-VLS for K-SAAM, Red Shark, and land-attack missiles, and CODLOG propulsion; a Daegu-based export variant has also been selected for Peru under an April 16, 2024, agreement between Hyundai Heavy Industries and SIMA covering four naval vessels.

FFX Batch III, under which the Chungnam class and ROKS Jeonnam are being built, has a budget of about 2.869 trillion won for six ships between 2016 and 2028, with hull contracts distributed among Hyundai Heavy Industries, Samkang M&T, SK Oceanplant, and Hanwha Ocean. Within FFX Batch III, ROKS Chungnam (FFG-828) was laid down on April 25, 2022, launched on April 10, 2023, delivered on December 18, 2024, and commissioned on December 24, 2024, for service with the Second Fleet as the lead ship of the class. ROKS Gyeongbuk (FFG-829) was laid down on April 1, 2024, at SK Oceanplant, launched on June 20, 2025, and is scheduled for delivery in June 2026, with assignment to the First Fleet expected. ROKS Jeonnam (FFG-831) was laid down in September 2024 and launched on November 25, 2025, at SK Oceanplant in Goseong, with delivery planned for December 2026 and subsequent deployment with the Third Fleet after its operational integration phase.

Additional Batch-III ships with hull numbers FFG-832, FFG-833, and FFG-835 are planned for delivery between 2027 and 2028, with SK Oceanplant constructing the next hulls and Hanwha Ocean building the final pair. The Jeonnam name has previously been used by PG-86, a fast transport destroyer acquired from the United States and commissioned in 1967, and by FF-957, an indigenous Ulsan-class frigate commissioned in 1989 that served for 34 years before decommissioning in 2022 after participation in the 1999 First Battle of Yeonpyeong and the 2009 Daecheong Naval Battle. Looking ahead, FFX Batch IV is planned as a follow-on series of six ships between 2023 and 2032 with a budget of about 3.2525 trillion won, keeping a broadly similar hull form but integrating additional weapon-system improvements and domestically developed integrated machinery-control systems to replace Kwanggaeto the Great-class destroyers and complete the FFX program.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.