View source for Sejong the Great-class destroyer

{{Use dmy dates|date=August 2020}}
{{short description|Class of South Korean destroyers}}
{|{{Infobox ship begin}}
{{Infobox ship image
| Ship image = ROKS Sejong the Great (DDG 991) broadside view.jpg
| Ship caption = ROKS ''Sejong the Great'' (DDG-991)
}}
{{Infobox ship class overview
| Builders = *[[Hyundai Heavy Industries]]
*[[Daewoo Shipbuilding & Marine Engineering]]
| Operators = {{navy|South Korea}}
| Class before = {{sclass|Chungmugong Yi Sun-sin|destroyer|4}}
| Class after = [[KDDX-class destroyer]]
| Subclasses = 
| Built range = 
| In commission range = 
| Total ships building = 2
| Total ships planned = 6
| Total ships completed = 4
| Total ships cancelled = 
| Total ships active = 3
| Cost = $923 million<ref name=":1" />
}}
{{Infobox ship characteristics
| Hide header = 
| Header caption = 
| Ship type = [[Guided-missile destroyer]]
| Ship displacement = *7,650 tons standard displacement
*10,600 tons full load
| Ship length = Batch 1 {{convert|166|m|ftin|abbr=on}}, Batch 2 {{convert|170|m|ftin|abbr=on}}
| Ship beam = {{convert|21.4|m|ftin|abbr=on}}
| Ship draught = 
| Ship draft = {{convert|6.25|m|ftin|abbr=on}}
| Ship propulsion = * 4 × [[General Electric LM2500]] [[COGAG]];
* 2 × shafts;
* {{convert|100,000|shp|lk=in|abbr=on}} produced power
| Ship speed = exceeds {{convert|30|kn|lk=in}}
| Ship range = {{convert|5,500|nmi|abbr=on|lk=in}}
| Ship endurance = 30 days
| Ship complement = 300
| Ship sensors = * [[AN/SPY-1|AN/SPY-1D(V)]] multi-function radar
* [[AN/SPG-62]] fire control radar
* DSQS-21BZ-M hull-mounted sonar
* SQR-220K towed array sonar system
* Sagem Infrared Search & Track (IRST) system
| Ship EW = LIG Nex1 SLQ-200K ''Sonata'' [[electronic warfare]] suite
| Ship armament = * 1 × [[5"/54 caliber Mark 45 gun|5-inch (127 mm)/L62 caliber Mk 45 Mod 4]] naval gun
* 1 × 30 mm [[Goalkeeper CIWS]]
* 1 × [[RIM-116 Rolling Airframe Missile|RAM Block 1 CIWS]]
* 16 × [[SSM-700K Haeseong]] anti-ship missile
* 2 × triple torpedo tubes for:
** [[Chung Sang Eo (Blue Shark) torpedo|K745 Blue Shark torpedo]]
* 1 × 48-cell, 1 × 32-cell (80 cells) [[Mark 41 Vertical Launching System|Mk 41 VLS]] for:
** [[RIM-66 Standard|SM-2 Block IIIB/IV]]
* 1 × 48-cell [[Korean Vertical Launching System|K-VLS]] for:
** [[Hong Sang Eo (Red Shark) torpedo|K-ASROC Red Shark]]
** [[Hyunmoo III]] land attack cruise missiles
| Ship armor = 
| Ship aircraft = 2 × [[Super Lynx]] or [[SH-60 Seahawk]]
| Ship aircraft facilities = Hangar and helipad
| Ship notes = 
}}
|}
The '''''Sejong the Great''-class destroyers''' (Sejongdaewang-Geup Guchukam or [[Hangul]]: 세종대왕급 구축함, [[Hanja]]: 世宗大王級驅逐艦), also known as KDX-III, are three [[guided-missile destroyer]]s of the [[Republic of Korea Navy]] (ROKN).<ref name="auto">{{cite web |url=http://www.navyrecognition.com/index.php/news/defence-news/year-2013-news/december-2013-navy-naval-forces-maritime-industry-technology-security-global-news/1413-rok-republic-of-korea-navy-to-increase-kdx-iii-aegis-destroyers-to-six-by-2027-.html |title=ROK (Republic of Korea) Navy to increase KDX-III Aegis destroyers to six by 2027 |date=11 December 2013 |access-date=12 December 2013 |archive-url=https://web.archive.org/web/20131212071851/http://www.navyrecognition.com/index.php/news/defence-news/year-2013-news/december-2013-navy-naval-forces-maritime-industry-technology-security-global-news/1413-rok-republic-of-korea-navy-to-increase-kdx-iii-aegis-destroyers-to-six-by-2027-.html |archive-date=12 December 2013 |url-status=live }}</ref>

== Hull name ==
On 20 April 2007, [[Chief of Naval Operations (South Korea)|South Korean Chief of Naval Operations]] announced that the lead ship of KDX-III class destroyers will be referred to as ''Sejong the Great''. [[Sejong the Great]] ([[Hangul]]: 세종대왕) is the fourth king of the [[Joseon Dynasty]] of [[Korea]]. He is credited with the creation of the [[Hangul|indigenous Korean system of writing]].<ref>{{Cite journal|last=Kim-Renaud|first=Young-Key|date=Spring 2000|title=Sejong's Theory of Literacy and Writing|url=https://core.ac.uk/download/pdf/4818935.pdf|journal=Studies in the Linguistic Sciences|volume=30|pages=13–45|via=CORE}}</ref>

== Background ==
The ''Sejong the Great'' class is the third phase of the South Korean navy's [[Korean Destroyer eXperimental]] (KDX) program, a substantial shipbuilding 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]].<ref name=":0">{{Cite web |title=Sejong the Great (Sejongdaewang) class Destroyer - KDX-III |url=http://www.navyrecognition.com/index.php/132-republic-of-korea-navy-vessels-ships-and-equipment/rok-navy-frigates-a-destroyers/844-sejong-the-great-sejongdaewang-kdx-iii-class-aegis-destroyer-republic-of-korea-rok-navy-yulgok-yi-i-seoae-yu-seong-ryong-hyundai-heavy-industries-hhi-dsme-datasheet-pictures-photos-video-specifications.html |access-date=2022-12-26 |website=www.navyrecognition.com}}</ref>

At 8,500 tons standard displacement and 11,000 tons full load, the KDX-III ''Sejong the Great'' destroyers are the largest destroyers in the South Korean Navy and larger than most destroyers in the navies of other countries.<ref>{{cite web|url=http://www.defenseindustrydaily.com/drs-wins-multiplexing-contract-for-korean-aegis-destroyers-0431/|title=Koreas KDX-III AEGIS Destroyers|access-date=8 March 2010|archive-url=https://web.archive.org/web/20091211035207/http://www.defenseindustrydaily.com/drs-wins-multiplexing-contract-for-korean-aegis-destroyers-0431/|archive-date=11 December 2009|url-status=live}}</ref> They are built slightly bulkier and heavier than {{sclass|Arleigh Burke|destroyer|2}}s or {{sclass|Atago|destroyer|2}}s to accommodate 32 more missiles. As such, some analysts believe that this class of ships is more appropriately termed a class of [[cruisers]] rather than [[destroyers]].<ref>"Sejong the Great Class
Guided Missile Destroyer." http://www.military-today.com/navy/sejong_the_great_class.htm</ref> KDX-III are currently the largest ships to carry the Aegis combat system.<ref>{{cite web|url=http://www.defencetalk.com/aegis-weapon-system-verified-during-korean-navy-ship-trials-27828/|title=Aegis Weapon System Verified During Korean Navy Ship TrialsDefenceTalk.com - at DefenceTalk|website=www.defencetalk.com|access-date=21 October 2010|archive-url=https://web.archive.org/web/20101205084306/http://www.defencetalk.com/aegis-weapon-system-verified-during-korean-navy-ship-trials-27828/|archive-date=5 December 2010|url-status=live}}</ref>

== Armaments ==
''Sejong the Great''-class destroyers' main gun is the [[5"/54 caliber Mark 45 gun|127 mm/L62 Mk 45 Mod 4 naval gun]], an improved version of the same gun used on other warships from several other nations. Point-defense armaments include one 30&nbsp;mm [[Goalkeeper CIWS]] and a [[RIM-116 Rolling Airframe Missile|RIM-116 Rolling Airframe Missile Block 1 21-round]] launcher, the first Aegis platform to carry RAM.<ref>{{cite web|url=http://www.deagel.com/pandora/kdx-iii_pm00212001.aspx|title=KDX-III / DDH-III Sejongdaewang|publisher=Guide to Military Equipment and Civil Aviation|access-date=7 April 2009|quote=These ships will be the world's first combining proven AEGIS and RAM.|archive-url=https://web.archive.org/web/20061007093037/http://deagel.com/pandora/kdx-iii_pm00212001.aspx|archive-date=7 October 2006|url-status=live}}</ref> Anti-aircraft armament consists of [[RIM-66 Standard|SM-2 Block IIIA and IIIB]]<ref>{{cite web|title= Korea to acquire new missiles for Aegis destroyer|url= http://www.koreaherald.co.kr/NEWKHSITE/data/html_dir/2009/06/28/200906280009.asp|publisher= The Korea Herald|date= 28 June 2009 |access-date= 27 June 2009}}</ref><ref>{{cite web|title= Republic of Korea - SM-2 Standard Missiles|url= http://www.dsca.mil/PressReleases/36-b/2009/ROK_09-22.pdf|publisher= Defense Security Cooperation Agency|date= 26 May 2009|access-date= 27 June 2009|url-status= dead|archive-url= https://web.archive.org/web/20110527065207/http://www.dsca.mil/PressReleases/36-b/2009/ROK_09-22.pdf|archive-date= 27 May 2011}}</ref> in 80 total [[Mark 41 Vertical Launching System|Mk 41]] [[Vertical launching system|VLS]] cells. Block IIIB has added infrared (IR) induction mode to Block IIIA, improving interception capability.

[[Anti-submarine warfare]] armaments consists of both K-ASROC ''Hong Sang-uh'' (Red Shark) anti-submarine rockets, which have the same form as the U.S. [[RUR-5 ASROC|ASROC]], and 32 [[Chung Sang Eo|K745 LW ''Cheong Sang-uh'']] (Blue Shark) torpedoes. Anti-ship capability is provided by 16 SSM-700K ''Hae Sung'' (Sea Star) long-range anti-ship missiles, each with performance similar to the U.S. [[Harpoon (missile)|Harpoon]]. It is equipped on a navy ship that is built after the late KDX-II destroyers. Land-attack capability is provided by the [[Hyunmoo-3|Hyunmoo III]] cruise missile.<ref name=":0" />

'''Missile batteries'''
* Vertical Launching System: 128 total cells
** Mk 41 VLS 48 cells (Fwd)
** Mk 41 VLS 32 cells (Aft)
** [[Korean Vertical Launching System|K-VLS]] 48 cells (Aft)
* Anti-ship missile launchers:
**16 (4 × quadruple) launchers

== Capabilities ==
The ship features the [[Aegis Combat System]] (Baseline 7 Phase 1) combined with [[AN/SPY-1]]D(V) multi-function radar antennae.<ref>{{Cite web |last=LaGrone |first=Sam |date=2016-09-06 |title=New South Korean Destroyers to Have BMD Capability |url=https://news.usni.org/2016/09/06/new-south-korean-destroyers-ballistic-missile-defense-capability |access-date=2022-12-26 |website=USNI News |language=en-US}}</ref><ref name=":0" /> This gives the destroyers the ability to track missiles launched from anywhere in North Korea. This capability was demonstrated by the tracking of a North Korean missile in April 2009.<ref>{{cite web |title=Korea Launches 3rd Aegis Destroyer |url=http://english.chosun.com/site/data/html_dir/2011/03/25/2011032501098.html |url-status=live |archive-url=https://web.archive.org/web/20120614014446/http://english.chosun.com/site/data/html_dir/2011/03/25/2011032501098.html |archive-date=14 June 2012 |access-date=10 May 2012}}</ref>

The ''Sejong the Great''-class destroyers are often compared to the ''Arleigh Burke'' and ''Atago'' classes because they utilize the AN/SPY-1D multi-function radar, and have similar propulsion and capabilities. One notable difference between the ''Sejong the Great''-class ships and ''Arleigh Burke''s is the number of [[vertical launch system|VLS]] cells. Destroyers of the ''Sejong the Great'' class have a capacity of 128 missiles, as opposed to 96 on the ''Arleigh Burke'' class and the Japanese ''Atago''-class destroyers. The ''Sejong the Great'' class is thus one of the most heavily armed ships in the world,<ref>{{cite web |url=http://newwars.wordpress.com/2010/05/25/south-korean-naval-plight-our-own/ |title=South Korean Naval Plight Our Own |first=Mike |last=Burleson |publisher=New Wars |date=25 May 2010 |access-date=10 November 2011 |archive-url=https://web.archive.org/web/20111028055920/http://newwars.wordpress.com/2010/05/25/south-korean-naval-plight-our-own/ |archive-date=28 October 2011 |url-status=live }}</ref> with greater missile capacity than the Chinese [[People's Liberation Army Navy]] [[Type 055 destroyer]]<ref>[http://www.popularmechanics.com/military/navy-ships/a23526/chinas-new-guided-missile-destroyer/ China's New Guided Missile Destroyer To Be Its Biggest Yet] {{Webarchive|url=https://web.archive.org/web/20161206010218/http://www.popularmechanics.com/military/navy-ships/a23526/chinas-new-guided-missile-destroyer/ |date=6 December 2016 }} - Popularmachanics.com, 24 October 2016</ref> (112 VLS cells) and the U.S. Navy {{sclass|Ticonderoga|cruiser|0}} [[guided missile cruiser|guided-missile cruiser]] (122 VLS cells). The ''Sejong the Great'' class is surpassed in VLS depth only by the {{sclass|Kirov|battlecruiser|2}} with 352 missiles (entire missile load).<ref>[http://www.military-today.com/navy/kirov_class.htm Kirov class] {{Webarchive|url=https://web.archive.org/web/20160304200138/http://www.military-today.com/navy/kirov_class.htm |date=4 March 2016 }} - Military-Today.com</ref>

Another similarity to ''Arleigh Burke'' Flight IIA and ''Atago''-class destroyers is the presence of full facilities for two helicopters,<ref name=":1">{{Cite web |title=Sejong the Great Class Guided Missile Destroyer {{!}} Military-Today.com |url=http://www.military-today.com/navy/sejong_the_great_class.htm |access-date=2022-12-26 |website=www.military-today.com}}</ref> a feature missing from earlier ''Arleigh Burke''<ref>{{Cite web |title=DDG-51 ARLEIGH BURKE-class - Navy Ships |url=https://man.fas.org/dod-101/sys/ship/ddg-51.htm |access-date=2022-12-26 |website=man.fas.org}}</ref> and {{sclass|Kongō|destroyer|2}}s.<ref>{{Cite web |title=Kongo class |url=https://weaponsystems.net/system/617-Kongo+class |access-date=2022-12-26 |website=Weaponsystems.net |language=en}}</ref>

===BMD===
In August 2016, press reports revealed that South Korea was considering adding the [[SM-3]] interceptor to its ''Sejong the Great''-class ships to enable them to perform [[ballistic missile defense]] in response to North Korean efforts to bolster offensive missile capabilities. This came months after the U.S. decision to deploy the [[THAAD]] missile interceptor system on mainland South Korea. The addition of SM-3s to the ships may require software and computer hardware upgrades.<ref>[https://news.usni.org/2016/08/15/report-south-korea-wants-bmd-capability-guided-missile-destroyers Report: South Korea Wants BMD Capability for Guided Missile Destroyers] {{Webarchive|url=https://web.archive.org/web/20160815133049/https://news.usni.org/2016/08/15/report-south-korea-wants-bmd-capability-guided-missile-destroyers |date=15 August 2016 }} - News.USNI.org, 15 August 2016</ref> The following month, Aegis manufacturer [[Lockheed Martin]] confirmed the next three ''Sejong the Great'' vessels 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. While the first three destroyers are fitted with Aegis Baseline 7 based on older proprietary computers that can't carry out IAMD operations, the following three will be fitted with the Baseline 9 version of the Aegis Combat System that combines modern computing architecture to allow the AN/SPY-1D(V) radar to perform air warfare and BMD missions at the same time.<ref>[https://news.usni.org/2016/09/06/new-south-korean-destroyers-ballistic-missile-defense-capability New South Korean Destroyers to Have Ballistic Missile Defense Capability] {{Webarchive|url=https://web.archive.org/web/20160907153108/https://news.usni.org/2016/09/06/new-south-korean-destroyers-ballistic-missile-defense-capability |date=7 September 2016 }} - News.USNI.org, 6 September 2016</ref>

== Ships in the class ==
{|class=wikitable
! Name || Pennant number || Builder || Launched || Commissioned || Status
|-
!colspan="6"| Batch I
|-
|{{ROKS|Sejong the Great|DDG-991|6}} (Korean: 세종대왕함)
|DDG-991
|Hyundai Heavy Industries
|25 May 2007
|22 December 2008
|Active
|-
|{{ROKS|Yulgok Yi I|DDG-992|6}} (Korean: 율곡 이이함)
|DDG-992
|Daewoo Shipbuilding & Marine Engineering
|14 November 2008
|31 August 2010
|Active
|-
|{{ROKS|Seoae Ryu Seong-ryong|DDG-993|6}} (Korean: 서애 류성룡함)
|DDG-993
|Hyundai Heavy Industries
|24 March 2011
|30 August 2012
|Active
|-
!colspan="6"| Batch II
|-
|ROKS ''Jeongjo the Great'' (Korean: 정조대왕)
|DDG-995
|Hyundai Heavy Industries
|28 July 2022
|
|Launched
|}
 
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. The ''Sejong the Great'' class is KDX-III Batch-I, and Korean Navy is planning 3 ships of KDX-III Batch-II.<ref>{{cite web|url=https://m-en.yna.co.kr/view/AEN20191010006400320|title=Hyundai Heavy bags 677 bln-won deal to build upgraded Aegis destroyer|date=10 October 2019|access-date=10 October 2019}}</ref> Under the deal, HHI will deliver the first ship by November 2024.<ref>{{cite web|url=https://www.navalnews.com/naval-news/2020/05/south-koreas-mid-term-defense-procurement-plan-largely-unaffected-by-covid-19-crisis/|title=South Korea's Mid-Term Defense Procurement Plan Largely Unaffected By COVID-19 Crisis |date=May 2020}}</ref>

==See also==
* [[List of naval ship classes in service]]
* [[List of active Republic of Korea Navy ships]]

== References ==
{{reflist|30em}}

== External links ==
* [http://www.globalsecurity.org/military/world/rok/kdx-3.htm KDX-III Destroyer]
* [http://www.deagel.com/pandora/kdx-iii_pm00212001.aspx KDX-III armaments] {{Webarchive|url=https://web.archive.org/web/20061007093037/http://deagel.com/pandora/kdx-iii_pm00212001.aspx |date=7 October 2006 }}

{{Sejong the Great-class destroyer|state=expanded}}
{{Republic of Korea Navy ships}}

[[Category:Sejong the Great-class destroyers| ]]
[[Category:Destroyers of the Republic of Korea Navy]]
[[Category:Destroyer classes]]