South Korean shipbuilder Hyundai Heavy Industries (HHI) launched the lead ship of the first Sejong the Great-class destroyer (KDX-III) Batch II Jeongjo the Great for the Republic of Korea Navy (ROKN) at the Hyundai Heavy Industries shipyard in Ulsan. Based on the existing Sejong the Great-class the new destroyers feature several improvements including improved combat systems. On 10 October 2019, HHI signed a deal to build the first of three 170m long, KDX-III Batch II Aegis destroyers for the Republic of Korea Navy. Sejong the Great-Class is KD-III batch-I, and Korean Navy is planning 3 ships of KDX-batch-II, and 3 ships of KDX-III-batch-III. Under the deal, HHI will deliver the first ship by November 2024.
The Sejong the Great-class destroyers features the Aegis Combat System (Baseline 7 Phase 1) combined with AN/SPY-1D multi-function radar antennae. The Sejong the Great class is the third phase of the South Korean navy’s Korean Destroyer eXperimental (KDX) program, which is geared toward enhancing ROKN’s ability to successfully defend the maritime areas around South Korea from various modes of threats as well as becoming a blue-water navy. At 8,500 tons standard displacement and 11,000 tons full load, the KDX-III Sejong the Great destroyers are by far the largest destroyers in the South Korean Navy, and indeed are larger than most destroyers in the navies of other countries. King Jeongjo is 600 tons larger than the King Sejong class (7,600 tons) destroyer.
The KDX-III Batch II will be fitted with SM-2 Block IIIB surface-to-air air defence missile. The medium-to-long-range surface-to-air missile is part of the Standard missiles family, which also includes the Standard Missile-6 (SM-6). The decision to procure SM-6 has not been made yet and will depend on budget. The missile provides protection against anti-ship missiles and aircraft, as well as threats flying close to the water’s surface. The Jeongjo the Great will feature several improvements including improved combat systems that can detect and track targets at greater distances and anti-ballistic missile capability with Raytheon’s SM-3 (RIM-161 Standard Missile 3) Block IB interceptors.
The Sejong the Great-class destroyers are often compared to the Arleigh Burke and Atago classes because they utilize the AN/SPY-1 multi-function radar, have similar propulsion and capabilities. One notable difference between the Sejong the Great-class ships and Arleigh Burkes is the number of VLS cells.These destroyers have the capability to track and monitor missiles launched from anywhere in North Korea. This capability was demonstrated by the tracking of a North Korean missile in April 2009. Lockheed Martin is in charge of delivering the AN/SPY-1D(V) multi-function radar as well as the AEGIS combat system for the KDX III Batch II ship. The Sejong the Great-class destroyers will be capable of performing “integrated air and missile defense” (IAMD) to supplement U.S. Army ground-based missile interceptors on the peninsula, likely being outfitted with the SM-3.