KDX-III Sejong Destroyer

The Republic of Korea Navy (ROKN) has embarked on a substantial shipbuilding program for its Korean Destroyer Experimental (KDX). It is a three-phased program consisting of three individual classes of ships: KDX-I (3800 tons) with Initial Operational Capability (IOC) of 1998, KDX-II (5000 tons) with IOC 2002, and KDX-III (7000-9000 tons) with IOC 2007/2008. Each phase gets more ambitious with respect to ship size, sensors, and weapons. As of 2000 planning was for three KDX-I class, six KDX-II, and at least one KDX-III class ships. The USN sold a substantial amount of materials and technical support for the KDX-I and KDX-II ships.

KDX-III was to be a larger (7000 tons or greater), more "Aegis-like" ship (Aegis Combat System with the ship incorporating certain Low Observables (LO/CLO) technology). The KDX-III' standard displacement is 7,000t, while its full load displacement would be above 9,000t.

Three or four KDX-III hulls were expected. After the first ship was completed in 2008, the ministry expected to deploy two other KDX- III destroyers in 2010 and 2012, respectively. By one estimate each vessel will cost about 1.2 trillion won ($923 million). The entire project, including the ships themselves, is expected to cost 2.8 trillion won by other estimates. The ROK KDX-III destroyer is intended to be a multi-purpose destroyer featuring anti-air warfare, anti-surface warfare, anti-submarine warfare and tactical ballistic missile defense capabilities.

This platform will enable the ROKN to successfully defend the maritime areas around the Korean peninsula from air, surface, and subsurface threats, and will increase interoperability with the USN. The base hull of the King Sejong class was based on the US Alay Burke class destroyer , but it was enlarged by about 10%. This is due to the fact that 48 Korean vertical launchers ( KVLS ) were installed. KVLS is equipped with its own Cheon Ryong cruise missile and red shark anti-submarine missile.

The first vessel was scheduled to be operational in the year 2008. The Hyundai Heavy Industries Shipyard was working on the basic design of the platform, but the actual decision who is going to build the three vessels won't be taken until 2003/2004 after competition. The candidates were Hyundai Heavy Industries, Daewoo Shipbuilding & Marine Engineering and Hanjin Heavy Industries.

On 11 August 2004 South Korea's Navy said that it will begin constructing its first 7,000-ton-class Aegis-equipped destroyer as part of a three-phased naval force improvement program. The vessel will be the first of three Aegis-equipped destroyers which the South Korean Navy will develop by 2012 under the KDX-III program. South Korean Navy's first Aegis destroyer "King Sejong" was launched on 25 May 2007 in a ceremony at the Ulsan dockyard of Hyundai Heavy Industries in the southeastern port city of Ulsan. The 7,600-ton KDX-III destroyer made it the fifth country to have the Aegis integrated weapons control system following the US, Japan, Spain and Norway. The King Sejong is also equipped with locally developed ship-to-ship missiles and torpedoes as well as various ship-to-air missiles and ship-to-surface cruise missiles. Stealth technology was also used, making radar detection harder. The ship was to be deployed operationally in 2009 after test operations.

King Sejong the Great is regarded as the most enlightened king in Korean history. King Sejong was born in 1397, and ascended the throne in 1418 at the age of 21. He was the fourth king of the Choson dynasty. He died in 1450 at the age of 54. During his 32-year reign, King Sejong energetically promoted learning. He was responsible for the creation of the Korean Hangul alphabet, and this scientific alphabet is his most known achievement. King Sejong often referred to his sword and swordsmanship in his journal. And like a true warrior, he practiced the ways of war, but preferred peace. An entry from his journal states, "The sword is a weapon of peace. With this sword I stand ready to defend my lineage, my family, my friends, and always, always our blessed country."

In June 2006 the Defense Acquisition Program Administration, the Korean military acquisition agency, selected Daewoo Shipbuilding & Marine Engineering Co. to build the country's second Aegis-equipped destroyer. Daewoo was expected to deliver the destroyer to the Navy by the end of 2010. In July 2007 Daewoo Shipbuilding and Marine Engineering (DSME) began the steel cutting of the South Korean Navy's second KDX-III Aegis-equipped destroyer. The Seoul-based company said that following the start of the steel cutting the first keel would be laid in December, with launching scheduled for November 2008. On 16 November 2008 South Korea launched its second AEGIS KDX-III destroyer. The ship was built at the Daewoo Shipbuilding and Marine Engineering yard on Geoje Island in South Gyeongsang. The ship was named after Yulgok Yi I, a prominent Confucian scholar of the Joseon Kingdom (1392-1910).

The three KDX-III destroyers designed by South Korea's Hyundai Heavy Industries were expected to be in service by 2012. The ships were intended to replace the South Korean Navy's fleet of aging U.S.-built destroyers.

South Korea's Ministry of National Defense approved the construction of three more KDX-III Sejong the Great-class destroyers, along with three more KSS-III diesel-electric attack submarines. The procurement is worth $6.3 billion. The Defense Project Promotion Committee, a division of the Defense Acquisition Program Administration, decided on 30 April 2019 Tuesday to OK the $6.3 billion deal. The vessels are expected to join the Republic of Korea Navy by 2028. South Korea's Ministry of National Defense approved the construction of three more KDX-III Sejong the Great-class destroyers, along with three more KSS-III diesel-electric attack submarines. The procurement is worth $6.3 billion. The Defense Project Promotion Committee, a division of the Defense Acquisition Program Administration, decided on 30 April 2019 Tuesday to OK the $6.3 billion deal. The first boat, dubbed "Dosan Ahn Chang-ho," only put to sea for the first time in September 2018, Sputnik reported. The 3,450-ton sub is Seoul's first ballistic missile submarine and by far the largest of South Korea's 18 submarines, sporting 10 vertical launch tubes that can carry either ballistic missiles or cruise missiles. However, Dosan Ahn Chang-ho is still being tested and won't be delivered to the navy until at least 2020. That hasn't stopped Seoul, though, which hopes to have all four KSS-III subs in service by 2025. The King Sejong class helicopter uses a RAST class that can operate only Sea State 5, which is roughly equivalent to a rough wave, and is operated only by the helicopter traversing system. This is a controversial issue, because the future battlefield situation is such a bad weather condition that soon appears as a difference in performance.

The disadvantage is that the operating cost of one King Sejong King is so huge that it costs just as much as the total operating cost of the Chungmugong Yi Shin class . This point seems to be a difficult problem for the Korean Navy in the future. The reason for this crazy price is not the performance problem of the ship itself, but rather the high oil price together with 300 crew, the relatively high maintenance and management costs of the Aegis system should also be considered.

The KDX-III destroyers are frequently described by Korean media as having a displacement of 7,000-tons or 7,600-tons, but as is frequently the case in Asia, this is the light displacement. The fully loaded displacement is more along the lines of 11,000 tons, larger the the US Ticondaroga class cruiser.