View source for K1 tank

{{Short description|South Korean main battle tank}}
{{Redirect|K1A1|the rifle|Daewoo Precision Industries K1}}
{{Use American English|date=April 2024}}
{{Infobox weapon
| name               = K1
| image              = File:2013.4.1 육군11사단 야외기동전술훈련 Field Training Exercise, Republic of Korea Army 11th Division (8617306085).jpg
| image_size         = 300
| caption            = Field training exercise of the [[11th Maneuver Division|11th Division]] of the South Korean army in April 2013
| origin             = [[South Korea]]
| type               = [[Main battle tank]]
| is_vehicle         = yes
| design_date        = {{Ubl
 | K1: 1978–1985
 | K1A1: 1991–1996
}}
| manufacturer       = {{Ubl
 | [[Hyundai Rotem|Hyundai Precision Industry]] (1985–2000)
 | [[Hyundai Mobis]] (2000–2001)
 | [[Hyundai Rotem|Rotem Co., Ltd.]] (2001–2007)
 | [[Hyundai Rotem]] (2007–present)
 }}
| unit_cost          = {{Ubl
 | K1: {{SK won|2.3&nbsp;billion|link=yes}} (1994)<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003782089?sid=100|title=北韓무력부 독자적 軍예산 편성|publisher=[[Yonhap News Agency]]|date=21 July 1994|archiveurl=https://web.archive.org/web/20221224030207/https://n.news.naver.com/mnews/article/001/0003782089?sid=100|archivedate=24 December 2022|accessdate=24 December 2022|author=}}</ref>
 | K1A1: {{SK won|4.4&nbsp;billion}} (2001)
 | K1A2: {{SK won|6.0&nbsp;billion}}
 }}
| designer           = {{Tree list}}
* [[Chrysler Defense]]
** [[General Dynamics Land Systems]]
* [[Hyundai Rotem|Hyundai Precision Industry]]
* [[Agency for Defense Development]]
{{Tree list/end}}
| service            = {{Ubl
 | K1: 1987–present
 | K1E1: 2014–present
 | K1A1: 2001–2024
 | K1A2: 2013–present
 }}
| used_by            = See [[#Operators|operators]]
| production_date    = {{Ubl
 | K1: 1987–1997
 | K1E1: 2014–present
 | K1A1: 1999–2011
 | K1A2: 2012–2024
 }}
| number             = {{Ubl
 | K1/E1: 1,027
 | K1A1/A2: 484
 }}
| crew               = 4
| length             = {{Ubl
 | K1: 9.67&nbsp;m (gun forward)
 | K1A1: 9.71&nbsp;m (gun forward)
 }}
| width              = 3.60&nbsp;m
| height             = 2.25&nbsp;m
| weight             = {{Ubl
 | K1: {{Nowrap|51.1 [[metric ton]]s}}
 | K1A1: {{Nowrap|53.2 metric tons}}<ref>{{cite web|url=https://www.hyundai-rotem.co.kr/Eng/Common/data/K1A1.pdf|title=K1A1 Main Battle Tank(MBT)|publisher=[[Hyundai Rotem]]|date=|archiveurl=https://web.archive.org/web/20120321030812/http://www.hyundai-rotem.co.kr/Eng/Common/data/K1A1.pdf|archivedate=21 March 2012|accessdate=31 January 2012|author=}}</ref>
 | K1A2: {{Nowrap|54.5 metric tons}}
 }}
| armour             = {{Ubl
 | K1: [[Chobham armour|Special Armor Package (SAP)]]
 | K1A1: Korean Special Armor Plate (KSAP)
 }}
| primary_armament   = {{Ubl
 | K1, K1E1:
* [[M68 (tank gun)|KM68A1]] 105&nbsp;mm (47 rounds)
 | K1A1, K1A2:
* [[M256 (tank gun)#KM256|KM256]] 120&nbsp;mm (32 rounds), or<br /> [[Hyundai WIA]] CN03 120&nbsp;mm (32 rounds)
 }}
| secondary_armament = {{Ubl
 | [[M2 Browning|M2]] or K6 [[.50 BMG|12.7x99 mm NATO]] HMG (commander's mount)
 | [[M60 machine gun|M60D]] [[7.62×51mm NATO]] GPMG (loader's mount)
 | [[M60 machine gun#M60E2|M60E2-1]] [[7.62×51mm NATO]] GPMG (coaxial)
 }}
| engine             = [[STX Engine]]/[[MTU Friedrichshafen]] MB871Ka-501 [[8-cylinder]] [[water-cooled]] [[turbocharged]] [[diesel engine]]
| engine_power       = 1200&nbsp;hp (890&nbsp;kW) @ 2600&nbsp;rpm
| transmission       = Hyundai Transys/[[ZF Friedrichshafen]] LSG 3000<br />Automatic, 4 forward, 2 reverse
| suspension         = Hydropneumatic (wheel 1, 2, 6),<br />torsion bar (wheel 3, 4, 5)
| clearance          = {{convert|460|mm|in|abbr=on}} {{Ubl
 | longitudinal slope: 60 %
 | lateral slope: 30 %
 | vertical: 1.1 m
 | trench: 2.74 m
 | fording: 1.2 m (without snorkel) or 2.2 m (with snorkel)
 }}
| speed              = {{Ubl
 | {{Convert|65|kph|mph|abbr=on}} (roads)
 | {{Convert|40|kph|mph|abbr=on}} (cross-country)
 }}
| pw_ratio           = {{Ubl
 | K1: 23.4&nbsp;hp/ton (17.44 kW/t)
 | K1A1: 22.5&nbsp;hp/ton (16.77 kW/t)
 | K1A2: 22&nbsp;hp/ton (16.40 kW/t)
 }}
| vehicle_range      = 500&nbsp;km (cruise)
}}

The '''K1''', sometimes referred to as the '''88 Tank (88 전차)''',<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=eazbQd6DH3E&ab_channel=KTV%EC%95%84%EC%B9%B4%EC%9D%B4%EB%B8%8C |title=대한뉴스 제 1663호-88전차 명명식 |date=2017-01-01 |last=KTV 아카이브 |access-date=2025-02-11 |via=YouTube}}</ref> is a South Korean [[main battle tank]] designed by [[Chrysler Defense]] (later [[General Dynamics Land Systems]]) and Hyundai Precision Industry (later [[Hyundai Rotem]]) for the [[Republic of Korea Armed Forces]]. It is a derivative of [[Chrysler|Chrysler's]] [[M1 Abrams]], tailored to meet the ROK's unique requirements.<ref>{{Cite book |author=United States Congress Senate Committee on Armed Services|url=https://www.google.com/books/edition/Department_of_Defense_authorization_for/oewAz6ajak4C?hl=en&gbpv=1&dq=ROKIT&pg=PA57&printsec=frontcover |title=Department of Defense authorization for appropriations for fiscal years 1990 and 1991: hearings before the Committee on Armed Services, United States Senate, One Hundred First Congress, first session, on S. 1085 |date=1989 |publisher=U.S. Government Printing Office |language=en}}</ref><ref name="K1 interview part 1">{{cite web|url=https://www.youtube.com/watch?v=ucDjQtMbuas|title=[첨단국가의 초석, 방위산업] 한국형 전차 K1 개발사 ①|publisher=국방TV|date=17 January 2016|archiveurl=https://web.archive.org/web/20221211071147/https://www.youtube.com/watch?v=ucDjQtMbuas|archivedate=11 December 2022|accessdate=11 December 2022|author=Defense Media Agency}}</ref><ref>{{Cite book |last=Lett |first=Philip |title=International Defense Review 1/1988: Korea's Type 88 comes of age |date=January 1988 |publisher=Janes}}</ref> The '''K1A1''' is an upgraded variant based on the GDLS technical data package with a [[Rheinmetall Rh-120|120&nbsp;mm 44 caliber]] [[smoothbore]] gun, and is outfitted with more modern electronics, ballistic computers, fire control systems, and armor. Hyundai Rotem produced 1,511 K1 and K1A1 tanks between 1986 and 2011.

== Development ==
[[File:2014. 1. 1 육군 8사단 K-1 Republic of Korea Army 8th Division (11794423924).jpg|left|thumb|K1 combat firing practice, [[8th Maneuver Division (South Korea)|8th Division]]]]

In the early 1970s, South Korea received an intelligence report about North Korea locally producing Soviet [[T-62]] tanks. Meanwhile, the U.S. [[7th Infantry Division (United States)|7th Infantry Division]] began withdrawing from South Korea from 1969 to 1971 under the [[Nixon Doctrine]]. South Korean President [[Park Chung Hee]] requested the latest variant of [[M60 tank]]s to maintain the balance of power. However, the [[United States]] responded by transferring used [[M48 Patton|M48 tanks]] and providing upgrades instead; South Korea received 25 M48A5s from the [[United States Forces Korea]] and numerous M48A3s that were used, but in good condition, during the [[Vietnam War]].<ref name="M48 Korean upgrade">{{cite web|url=https://www.youtube.com/watch?v=LrAOvjP2hT4|title=[첨단국가의 초석, 방위산업] 한국형 전차 개발의 씨앗, M48 개조사업|publisher=국방TV|date=15 January 2016|archiveurl=https://web.archive.org/web/20221224033952/https://www.youtube.com/watch?v=LrAOvjP2hT4|archivedate=24 December 2022|accessdate=24 December 2022|author=Defense Media Agency}}</ref>

Under the agreement, South Korea received the technical data package (TDP) of the M48 Patton and its upgrade kits for 12 major enhancements. Korean engineers were sent to the United States Army Depot in Alabama for training, such as armor cast steel welding and production, precision manufacturing, assembling skills, quality inspection, and test evaluation. Around the same time, Park Chung Hee ordered the development of a domestic tank and personally summoned [[Chung Ju-yung]], the founder of [[Hyundai Group]], to recommend building a tank factory. Chung Ju-yung, thinking that the president asked for a train factory, promised to build one.{{notetag|The Korean words for tank and train are written and spoken exactly the same: 전차 (jeoncha). The only difference is their Hanja: tank (戰車) vs train (電車).}} The chairman was shocked after learning about his misunderstanding from the president's secretary as he was leaving the building.<ref name="M48 Korean upgrade"/><ref name="Hyundai Precision">{{cite web|url=https://koreascience.kr/article/JAKO199841548401849.pdf|title=방산업체 소개-자주 국방의 선봉 현대정공(주)|publisher=Defense and Technology (국방과기술)|date=1 May 1998|archiveurl=https://web.archive.org/web/20220927064949/https://koreascience.kr/article/JAKO199841548401849.pdf|archivedate=27 September 2022|accessdate=27 September 2022|author=Korea Defense Industry Association}}</ref>

Not satisfied with the M48 Patton upgrade, South Korea began looking for a new tank that could overwhelm every North Korean counterpart, as the existence of the T-62 and its manufacturing facility were confirmed by satellite images in 1976. South Korea first asked Chrysler Defense for a solution to acquire a better tank, and Chrysler suggested purchasing the M60A3 or producing it in South Korea. Because the American offer was an outdated design, South Korea then contacted [[KraussMaffei]] of West Germany to receive technical assistance, and KraussMaffei offered a unique tank design based on the [[Leopard 1]]. Both South Korea and West Germany kept the cooperation secret because the two nations believed that the United States would intervene once the information had been leaked. In 1977, as expected, Chrysler Defense showed interest in the Korean tank project after its engineers became available and wanted to generate more profit after the development of the [[M1 Abrams]]. This time, Chrysler offered a new tank based on the newest M1 Abrams. Eventually, the American design was chosen, and a [[memorandum of understanding]] (MOU) was signed on 6 July 1978 to supply two prototypes, and the executive contract was signed on 1 December 1978.<ref name="K1 interview part 1"/><ref name="M48 Korean upgrade"/><ref name="Hyundai Precision"/><ref name="K1 interview part 2">{{cite web|url=https://www.youtube.com/watch?v=CpnoMqP6rZ4|title=[첨단국가의 초석, 방위산업] 한국형 전차 K1 개발사 ②|publisher=국방TV|date=17 January 2016|archiveurl=https://web.archive.org/web/20221211071241/https://www.youtube.com/watch?v=CpnoMqP6rZ4|archivedate=11 December 2022|accessdate=11 December 2022|author=Defense Media Agency}}</ref>

Between 1979 and 1980, several MOUs were signed between the two nations, mostly regarding intellectual rights and royalty payments. According to the MOUs, the United States would provide and install its state-of-art Special Armor Package (SAP), in which the material and protection were identical to the M1 Abrams, while restricting Koreans during its installation due to national security reasons. Exporting of the K1 is strictly controlled and needs authorization from the United States as many sensitive systems are installed, and South Korea was required to pay a royalty to Chrysler Defense. Also, 44 designated parts (gradually reduced to 14) cannot be changed without United States approval, and some parts must be purchased periodically. In addition, South Korea would have the rights on, and be limited to, the technologies developed uniquely with the money provided by South Korea, while Chrysler also claimed the rights to use them in the future. On the other hand, South Korea benefited from the development cost of the cooperation with Chrysler; South Korea paid $60 million for the prototype development, far below the $700 million spent on the M1 Abrams. However, the biggest disadvantage in the agreement for South Korea was that Hyundai Precision Industry, which had planned to produce the tank at its new factory, was excluded from direct involvement in designing the tank. Since Koreans had not made tanks before, they would be unable to produce tanks as they did not understand the structure and technology of the tank even with prototypes in hand.<ref name="K1 interview part 1"/>

From October 1980 to April 1981, Chrysler had three meetings with Hyundai to confirm the required operational capability (ROC) and presented a small-scale mock-up and reports. During the production of the prototypes, Chrysler Defense was sold to [[General Dynamics Land Systems]] (GDLS) in March 1982. Two prototypes named ROKIT (Republic of Korea Indigenous Tank) were produced with designations PV-1 (MTR - mobility test rig) and PV-2 (FTR - firepower test rig) in 1983 after three years of development and went to trial at [[Aberdeen Proving Ground]] based on American military standards. During the trial, the PV-1 failed to climb the longitudinal slope of 60%, experienced a fire on the 1,200&nbsp;hp Teledyne Continental Motors AVCR-1790 engine, and had issues with its transmission. PV-2 also reported issues with its fire control system: the LOS (line of sight) was shaking due to frost in the winter season, it was taking too long to warm up, there was interference from electromagnetic waves, and the ballistic computer was locking up. Protection tests were done on separately built ballistic hulls and turrets, which showed some flaws during the test. Eventually, the known problems were fixed and improved by the time of delivery of the two prototypes. In the end, GDLS transferred the PV-1 along with 1,370 pages of blueprints and the TDP, but the number of blueprints was insufficient for manufacturing.<ref name="Hyundai Precision"/><ref name="K1 interview part 2"/>

During the trial, a team of Korean engineers from Hyundai Precision Industry was dispatched to join Chrysler's developer team to look over the progress. Although the contract limits the technological access of Koreans, engineers from both nations freely shared information during friendship interactions, including a classified specification of the M1 Abrams. When the upper management of Chrysler found out about this, they built a wall in the office to prevent information leakage. However, Koreans managed to obtain significant data during their three-year presence at the facility. In addition, the manufacturing team of Hyundai came for a tour of the American tank factory to understand how to build a tank factory. Koreans could only go to the specified path, but they memorized types of machinery and calculated the required sizes of the facility by counting theïr footsteps, which helped them to build the new factory at [[Changwon]].<ref name="Hyundai Precision"/><ref name="K1 interview part 2"/>

In 1983, Hyundai accepted GDLS' new offer and acquired special welding of armor plates, assembly of major devices, and weapon testing technologies. Thirty engineers from GDLS were also sent to Korea and participated in producing and testing preproduction models. From September 1984 to August 1985, a total of five XK1s were completed (two for the [[Agency for Defense Development]] (ADD), two for the ROK Army, and one for the Army logistics), and went for further testing in South Korea. However, Hyundai realized that GDLS had made a crucial mistake by providing outdated blueprints that did not reflect the latest fixes, and XK1s began to experience the same issues they saw from early prototypes. In addition, the lack of detailed blueprints forced Korean engineers to rework the tank and create five thousand design changes and ten thousand pages of blueprints. The biggest change during this process was the switching of the mobility system from American to German, in which the design change was done by GDLS. The air-cooled AVCR-1790 had lower torque, was thus unable to drive at high incline angles, and experienced fire several times, contributing to unexpected fire tests that challenged the tank's survivability. For this reason, the [[MTU Friedrichshafen]] MB871Ka-501 water-cooled engine and the [[ZF Friedrichshafen]] LSG 3000 transmission were chosen for the new power pack.<ref name="K1 interview part 2"/><ref name="K1 interview part 3">{{cite web|url=https://www.youtube.com/watch?v=bzb0ZRIQ8k0|title=[첨단국가의 초석, 방위산업] 한국형 전차 K1 개발사 ③|publisher=국방TV|date=17 September 2016|archiveurl=https://web.archive.org/web/20220925112505/https://www.youtube.com/watch?app=desktop&v=bzb0ZRIQ8k0|archivedate=25 September 2022|accessdate=25 September 2022|author=Defense Media Agency}}</ref><ref name="K1 MBT">{{cite web|url=https://kookbang.dema.mil.kr/newsWeb/20200420/1/BBSMSTR_000000100008/view.do|title=K1 주력전차|publisher=Kookbangilbo|date=20 April 2020|archiveurl=https://web.archive.org/web/20221224045644/https://kookbang.dema.mil.kr/newsWeb/20200420/1/BBSMSTR_000000100008/view.do|archivedate=24 December 2022|accessdate=24 December 2022|author=Shin In-ho}}</ref> These preproduction variants entered service with the South Korean military in February 1986.<ref name="Hyundai Precision"/><ref>{{cite web|url=https://n.news.naver.com/mnews/article/008/0000235293?sid=101|title=[기업] 로템 연말 군부대 위문 방문|publisher=Money Today|date=23 December 2002|archiveurl=https://web.archive.org/web/20220928192857/https://n.news.naver.com/mnews/article/008/0000235293?sid=101|archivedate=28 September 2022|accessdate=28 September 2022|author=Kim Jeong-tae}}</ref>

Meanwhile, Hughes' GPSS (Gunner's Primary Sight System) continuously suffered with issues such as low accuracy and operational uses. Also, South Korea gave up localizing the GPSS as Hughes doubled the price for the license. Later, GDLS, which acquired Hughes in 1985, revealed that the system uses parts from Canada, West Germany, and Switzerland, and thus requires time-consuming multinational cooperation to solve problems. In 1986, another contract was signed between Hyundai and GDLS for updating the GPSS, increasing the cost of the gunner's sight. This unsatisfactory situation led South Koreans to look for alternative options immediately. In April 1987, the K1 tank test evaluation for conditional mass production was completed, and serial production began in September 1987. On 18 September, the tank was given the nickname '''88-Tank''' by South Korean president [[Chun Doo-hwan]] to celebrate the upcoming [[1988 Summer Olympics]].<ref name="Hyundai Precision"/><ref name="K1 interview part 2"/><ref name="K1 interview part 3"/><ref>{{cite web|url=http://monthly.chosun.com/client/news/viw.asp?ctcd=J&nNewsNumb=200810100031|title=차세대 戰車 '흑표' 생산하는 현대로템|publisher=[[The Chosun Ilbo]]|date=10 October 2008|archiveurl=https://web.archive.org/web/20220920170512/http://monthly.chosun.com/client/news/viw.asp?ctcd=J&nNewsNumb=200810100031|archivedate=20 September 2022|accessdate=20 September 2022|author=Oh Dong-ryong}}</ref><ref>{{cite web|url=https://imnews.imbc.com/replay/1987/nwdesk/article/1795679_29505.html|title=전두환 대통령 한국형 88전차 명명식[윤종보]|publisher=[[Munhwa Broadcasting Corporation|MBC]]|date=18 September 1987|archiveurl=https://web.archive.org/web/20201129071826/https://imnews.imbc.com/replay/1987/nwdesk/article/1795679_29505.html|archivedate=29 November 2020|accessdate=29 November 2020|author=Yoon Jong-bo}}</ref><ref name="GPS">{{cite web|url=https://www.edaily.co.kr/news/read?newsId=01108646612619072&mediaCodeNo=257|title=[e-무기]미국산 불량품 고치다 탄생한 한국형 전차의 '눈'|publisher=Edaily|date=23 April 2016|archive-url=https://web.archive.org/web/20220522172622/https://www.edaily.co.kr/news/read?newsId=01108646612619072&mediaCodeNo=257|archive-date=22 May 2022|access-date=22 May 2022|author=Kim Gwan-yong}}</ref>

A total of 1,027 K1s were produced between 1986 and 1997 in three batches with design changes in each batch. In 1995, the K1s received their first depot maintenance at Hyundai Precision Industry in the order of production (10-year cycle). The work includes the application of third batch updates on the earlier produced vehicles.<ref name="Hyundai Precision"/><ref name="K1M">{{cite web|url=https://kookbang.dema.mil.kr/newsWeb/20201116/1/BBSMSTR_000000100003/view.do|title=방산수출 지원과 정부기관 간 약정|publisher=Kookbang Ilbo|date=16 November 2020|archiveurl=https://web.archive.org/web/20221224134452/https://kookbang.dema.mil.kr/newsWeb/20201116/1/BBSMSTR_000000100003/view.do|archivedate=24 December 2022|accessdate=24 December 2022|author=}}</ref>

== General characteristics ==
[[File:K1A2 combat firing practice.webm|right|thumb|thumbtime=0:09|K1A2 combat firing practice]]

The K1 retains most of the features of the [[M1 Abrams]] but also shows differences. Its main armament is a licensed [[M68 (tank gun)|M68A1 105 mm 52 caliber tank gun]] under designation KM68A1 by Hyundai Precision Industry. The K1 carries 47 rounds of ammunition in the hull and turret. Unlike the M1 Abrams, the K1 lacks ammunition storage in the bustle at the rear of the turret, which is instead filled with radio systems. The main gun is assisted by a 16-bit fire control system and digital ballistic calculator. The tank has either an [[M2 Browning]] or [[SNT Dynamics]] K6 [[.50 BMG|12.7x99 mm NATO]] machine gun on the commander's hatch mount, an [[M60 machine gun|M60D]] [[7.62×51mm NATO]] machine gun on the loader's hatch mount, and an [[M60 machine gun#M60E2|M60E2-1]] [[7.62×51mm NATO]] coaxial machine gun for the gunner as secondary armaments.<ref name="K1 interview">{{cite web|url=https://www.dema.mil.kr/web/tv/replay/onair/47/800653/view.do|title=지상전의 왕자 K1A1전차|publisher=Defense Media Agency|date=21 July 2009|archiveurl=|archivedate=|accessdate=12 December 2023|author=}}</ref><ref name="K1 specification">{{cite web|url=https://koreascience.kr/article/JAKO199541548489556.pdf|title=지상전투의 핵심 한국형 K-1 전차|publisher=Korea Defense Industry Association|date=1 May 1995|archiveurl=https://web.archive.org/web/20220923053349/https://koreascience.kr/article/JAKO199541548489556.pdf|issn=1227-1705|volume=|number=|pages=8–9|archivedate=23 September 2022|accessdate=23 September 2022|author=}}</ref>

The K1 has a size of 9.67 m (length with gun forward) x 3.60 m (width) x 2.25 m (height) and weighs 51.1 t or 51.5 t.<ref name="K1 specification"/> It is powered by a German power pack consisting of 1,200&nbsp;hp (23.5&nbsp;hp/t) from [[MTU Friedrichshafen]] MB871Ka-501 [[8-cylinder]] [[water-cooled]] [[turbocharged]] [[diesel engine]] licensed by Ssangyong Heavy Industries (now STX Engine) and [[ZF Friedrichshafen]] LSG 3000 transmission licensed by Hyundai Precision Industry (now Hyundai Transys). The tank can drive at a maximum speed of 65&nbsp;km/h on paved roads and 40&nbsp;km/h cross-country with a 500&nbsp;km cruising range. Its chassis uses hybrid suspension combining [[hydropneumatic suspension]] on wheels 1, 2, and 6 and [[torsion bar]]s on wheels 3, 4, and 5. It allows the tank to use kneeling to supplement the depression of the main gun, which is limited by the small-sized turret to -10 degrees, and provides comfort on rough terrains.<ref name="K1 interview part 3"/><ref name="K1 MBT"/><ref name="K1 interview"/><ref name="K1 specification"/><ref>{{cite web|url=https://koreascience.kr/article/JAKO199141548479114.pdf|title=전차의 소개와 발전추세(1)|publisher=Korea Defense Industry Association|date=1 May 1991|archiveurl=https://web.archive.org/web/20220923034901/https://koreascience.kr/article/JAKO199141548479114.pdf|issn=1227-1705|volume=|number=|pages=80–86|archivedate=23 September 2022|accessdate=23 September 2022|author=Kim Dong-Jin}}</ref> For comparison, M1 Abrams is 9.77 m x 3.66 m x 2.37 m and weighs 54 t.

The Gun/Turret Drive and Stabilization System (GTDSS) measures and compensates for yawing and pitching, which occur on uneven ground and curved roads, allowing the gun turret to be capable of precise fire while running. The GTDSS consists of an elevation servo system, an elevation drive system, a reference gyro, a traverse servo system, a traverse drive system, a feed-forward gyro, an electronic unit for gun and turret drive, and a steering handle for the gunner. The system is locally produced in South Korea by Dongmyeong Heavy Industries (now Mottrol) since 1992.<ref>{{cite web|url=https://www.mottrol.com/download/defense/MOTTROL_Defense_Catalogue.pdf|title=Defense Applications & Solutions|publisher=[[Mottrol]]|date=|archive-url=https://web.archive.org/web/20221230075312/https://www.mottrol.com/download/defense/MOTTROL_Defense_Catalogue.pdf|archive-date=30 December 2022|access-date=30 December 2022|author=}} p. 5</ref>

The gunner's sight was initially a problematic Hughes GPSS, which uses an [[Nd:YAG laser]] [[Rangefinding telemeter|rangefinder]], a similar model to the one used for the M1 Abrams. Despite Koreans having decided to upgrade the existing GPSS, [[Samsung Electronics]] signed a deal with [[Texas Instruments]] to supply and locally produce the GPTTS (Gunner's Primary Tank Thermal Sight) in 1986. Hyundai originally planned to install the GPTTS in 1987, but serious problems such as the failure of the laser rangefinder forced Hyundai to postpone the plan. Due to the delays, a total of 445 K1s were produced with the Hughes GPSS installed. Meanwhile, after failing to repair the GPTTS, Texas Instruments gave access to technology to the [[Agency for Defense Development]] (ADD). Within a year, a combined team managed to fix the sight and further improve it by increasing the sight's range from 2&nbsp;km to 3&nbsp;km. Samsung Electronics began supplying the GPTTS in 1991. Later, during a parliamentary investigation, it was found that there were lobbies involved in selecting the GPTTS, leading to a selection of the product without proper testing, which caused an additional development cost of 16 billion KRW on the sight. Regardless of the involvement of lobbies, the upgraded GPTTS showed superior performance when shooting a hidden target behind a smoke screen, which the GPSS failed to do so during a test on 2 September 1993. The GPTTS uses a [[carbon dioxide laser]] range finder, which is safer for the human eye upon being hit by the laser, while Nd:YAG can blind the victim. However, the GPTTS was a complex and heavier system. Ironically, access to GPTTS technology enabled Koreans to design their own gunner's sight. The ADD and Samsung Electronics began the research in 1992 for a domestic gunner's primary sight (later known as KGPS: Korean Gunner's Primary Sight) using the [[Raman laser]] believing such technology would be used for future weapon systems. In 1995, by the time Koreans were at the end stage of development, Europe announced it would use Raman lasers for tanks, followed by the United States.<ref name="GPS"/><ref>{{cite web|url=https://www.mk.co.kr/news/politics/9554517|title=[단독 / 레이더P] 육군 주력전차 10대중 2대 포수조준경 고장...부품 없어 최장 8년 무력화|publisher=[[Maeil Business Newspaper]]|date=8 October 2020|archiveurl=https://web.archive.org/web/20230107170040/https://www.mk.co.kr/news/politics/9554517|archivedate=7 January 2023|accessdate=7 January 2023|author=Park Je-wan}}</ref><ref>{{cite web|url=https://www.hankyung.com/news/article/1993090600401|title=육군납품 포수조준경 GPTTS 제품성능 문제없다...삼성전자|publisher=[[Korea Economic Daily]]|date=6 September 1993|archiveurl=https://web.archive.org/web/20230107170813/https://www.hankyung.com/news/article/1993090600401|archivedate=7 January 2023|accessdate=7 January 2023|author=}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003830053?sid=100|title=<焦點> 國監 쟁점 상위위-1|publisher=[[Yonhap News Agency]]|date=10 October 1994|archiveurl=https://web.archive.org/web/20220824072424/https://n.news.naver.com/mnews/article/001/0003830053?sid=100|archivedate=24 August 2022|accessdate=24 August 2022|author=}}</ref><ref name="Yonhap News 1994-10-07">{{cite web|url=https://n.news.naver.com/mnews/article/001/0003829370?sid=100|title=國會 국정감사 계속(종합)|publisher=[[Yonhap News Agency]]|date=7 October 1994|archiveurl=https://web.archive.org/web/20220824072424/https://n.news.naver.com/mnews/article/001/0003830053?sid=100|archivedate=24 August 2022|accessdate=24 August 2022|author=}}</ref> A year later, in December 1996, a Raman laser type Korean Gunner's Primary Sight (KGPS) was developed.<ref>{{cite web|url=https://koreascience.kr/article/JAKO199841548325612.pdf|title=방산업체 소개-세계 초일류 통신.전자의 메카 삼성전자|publisher=Korea Defense Industry Association|date=1 May 2000|archiveurl=https://web.archive.org/web/20230410055953/https://koreascience.kr/article/JAKO199841548325612.pdf|archivedate=10 April 2023|accessdate=10 April 2023|author=}}</ref>

The commander's sight is from SFIM (now [[SAGEM]]) of France, and it has a hunter-killer ability that allows tank crews to engage multiple targets at once by allowing the commander to search 360 degrees and direct the main gun.<ref name="K1 interview part 3"/><ref name="GPS"/><ref name="K1 interview"/> The hunter-killer feature was a major difference compared to the M1 Abrams, where it only becomes available with the M1A2 upgrade. The commander's sight was not, however, equipped with light amplification or thermal optics, which led to the commander to rely on personal night vision goggles for night operation, while the gunner's sight was equipped with a thermal observation device, which meant that the K1 had superior sensors until the introduction of the M1A2.

The Special Armor Package (SAP) is a [[Chobham armour|classified composite armor]] used for the K1 tanks crafted by the United States using identical materials and technologies used on the armor of M1 Abrams. Its specifications are strictly restricted for public release and limit South Koreans from accessing the armor. The SAP is applied on the turret and the front of the hull. Meanwhile, the side of the hull is protected with additional [[Rolled homogeneous armour|RHA plates]], which provide protection from all types of 115&nbsp;mm ammunition fired from [[T-62]] tanks in the hands of North Korea at the time of the development.<ref name="K1 interview part 3"/> According to the media report, the frontal armor of the K1 baseline is between 400 and 500&nbsp;mm against KE projectiles.<ref name="k1 armor">{{cite web|url=https://biz.chosun.com/site/data/html_dir/2016/10/10/2016101001441.html|title=[방산 현장을 가다]⑥ 명품 전차 반열에 우뚝 'K2'... 현대로템을 가다|publisher=[[ChosunBiz]]|date=10 October 2016|archiveurl=https://web.archive.org/web/20161011170543/https://biz.chosun.com/site/data/html_dir/2016/10/10/2016101001441.html|archivedate=11 October 2016|accessdate=11 October 2016|author=Yoon Hee-hoon}}</ref> Smoke grenade launchers are located on each outer side of the turret front. The vehicle is also equipped with a fire-extinguishing system in the engine room, where the system notifies crews to activate automatic extinguishers when a thermometer detects a critical temperature.<ref name="K1 interview"/> The extinguishant used is [[Bromotrifluoromethane|Halon 1301]], commonly used by western main battle tanks. The vehicle lacks an overpressure system for [[CBRN defense]], and thus requires tank crews to wear personal protective gear to operate in [[chemical warfare|chemical]], [[biological warfare|biological]], [[radiological warfare|radiological]], and [[nuclear warfare|nuclear]] warfare environments.

=== K1A1 ===
[[File:육군 20사단 K1A1기동 (7445965714).jpg|thumb|K1A1 tanks of the 20th Mechanized Infantry Division of ROK Army is maneuvering through rough terrain.]]

In 1985, South Korea exercised its option (included in the previous contract) for a K1 upgrade plan report. GDLS responded with an upgraded K1 model with a 120&nbsp;mm smoothbore gun similar to the M1A1 Abrams gun. In the late 1980s, South Korea received multiple intelligence reports about North Korea purchasing [[T-72]] tanks, which had a 125&nbsp;mm smoothbore cannon. The intelligence report turned out to be false decades later. However, it alerted South Korea at that time as a 125&nbsp;mm smoothbore could fire from a farther distance and have higher penetration compared to a 105&nbsp;mm rifled cannon. Therefore, the South Korean government requested the ADD to make a new tank equipped with a 120&nbsp;mm cannon. In 1988, the ADD launched exploration development, and began official system development with Hyundai Precision Industry in 1991.<ref name="K1 interview"/><ref name="K1A1 interview">{{cite web|url=https://www.youtube.com/watch?v=FBSvXJL2eW0|title=[첨단국가의 초석, 방위산업] 한국형 전차 K1A1|publisher=국방TV|date=10 March 2016|archiveurl=https://web.archive.org/web/20221211071406/https://www.youtube.com/watch?v=FBSvXJL2eW0|archivedate=11 December 2022|accessdate=11 December 2022|author=Defense Media Agency}}</ref>

The ADD and Hyundai submitted a plan to redesign the tank by replacing most parts with the latest technology. However, the plan was rejected by the military as such an upgrade would require a budget over the limit, and too luxurious for a conscription army. Therefore, the ADD and Hyundai changed the plan by focusing on the weaponry by increasing the caliber to 120&nbsp;mm. Since South Korea did not know the specification of 120&nbsp;mm cannon, it decided to compare the cannons from the United States, Germany, France, and Israel, while ammunition was competed between the United States, which was a German design, and Israel. On 10 March 1994, Poongsan Corporation was selected as the main supplier of the 120&nbsp;mm tank ammunition. In September 1994, despite the Israeli [[IMI 120 mm gun]] showing better performance, easier logistics access made South Korea licence produce the American [[M256 (tank gun)|M256]] 120&nbsp;mm smoothbore, which was based on German [[Rheinmetall Rh-120]], as designation KM256. Meanwhile, on October 10, 1996, ADD announced that it would develop domestic 120&nbsp;mm ammunition without receiving technology transfer from foreign countries.<ref name="K1A1 interview"/><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003761098?sid=104|title=한국, 독일 무기에 관심|publisher=[[Yonhap News Agency]]|date=2 November 1993|archiveurl=https://web.archive.org/web/20230328232550/https://n.news.naver.com/mnews/article/001/0003761098?sid=104|archivedate=28 March 2023|accessdate=28 March 2023|author=Lee Sun-geun}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003861774?sid=102|title=K-1전차 120mm 탄약 주생산업체 선정|publisher=[[Yonhap News Agency]]|date=10 March 1994|archiveurl=https://web.archive.org/web/20230501074338/https://n.news.naver.com/mnews/article/001/0003861774?sid=102|archivedate=1 May 2023|accessdate=1 May 2023|author=}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003824366?sid=100|title=<國監현장>--국방위|publisher=[[Yonhap News Agency]]|date=12 October 1994|archiveurl=https://web.archive.org/web/20230328232550/https://n.news.naver.com/mnews/article/001/0003824366?sid=100|archivedate=28 March 2023|accessdate=28 March 2023|author=Lee Myeon-jo}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004080524?sid=100|title="잠수함 잡는 신형 輕어뢰 2001년 개발"(종합)|publisher=[[Yonhap News Agency]]|date=10 October 1996|archiveurl=https://web.archive.org/web/20230501083331/https://n.news.naver.com/mnews/article/001/0004080524?sid=100|archivedate=1 May 2023|accessdate=1 May 2023|author=Sung Ki-hong}}</ref>

On 7 October 1994, the ADD reported at a parliamentary inspection that the KGPS, fitted with a [[Raman laser]] rangefinder, was tested on the K1 and showed good performances. It was expected to be tested on an upgraded prototype in 1996.<ref name="Yonhap News 1994-10-07" />

The delivery ceremony of the K1A1 prototype was held on 3 April 1996. The major improvement was firepower, which increased the penetration from 300&nbsp;mm to 600&nbsp;mm and the effective range from 1.2&nbsp;km to 2.5&nbsp;km. South Korea expected to mass-produce the K1A1 in 1997.<ref name="K1A1 prototype">{{Cite web |title=한국형 120mm K-1 성능개량전차 첫 선 |url=https://n.news.naver.com/mnews/article/001/0004139885?sid=102 |access-date=2022-09-20 |website=[[Naver News]] |language=ko}}</ref><ref>{{Cite web |title=한국형전차 성능 대폭개량…K1A1 창원공장서 출고식 |url=https://n.news.naver.com/mnews/article/005/0000073334?sid=102 |access-date=2024-02-13 |website=[[Naver News]] |language=ko}}</ref> On 9 October, the ADD announced the development of the KGPS, which was developed by the technologies gained during the GPTTS upgrades.<ref name="GPS"/><ref name="KGPS">{{cite web|url=https://n.news.naver.com/mnews/article/001/0004072537?sid=102|title=전차포수조준경,熱영상장비 첫 개발|publisher=[[Yonhap News Agency]]|date=9 October 1996|archiveurl=https://web.archive.org/web/20230501102803/https://n.news.naver.com/mnews/article/001/0004072537?sid=102|archivedate=1 May 2023|accessdate=1 May 2023|author=}}</ref>

On 9 June 1998, the Ministry of Defense announced that mass production of K1A1 would begin in 1999, 2 years behind schedule due to the [[1997 Asian financial crisis]] that decreased the defense budget.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004300441?sid=102|title=국방예산 실질삭감 1조3천억-戰力증강사업 손질 불가피|publisher=[[Yonhap News Agency]]|date=6 February 1998|archiveurl=https://web.archive.org/web/20230501105008/https://n.news.naver.com/mnews/article/001/0004300441?sid=102|archivedate=1 May 2023|accessdate=1 May 2023|author=Lee Sung-han}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004386255?sid=100|title=잠수함.유도미사일 사업 내년 추진|publisher=[[Yonhap News Agency]]|date=8 June 1998|archiveurl=https://web.archive.org/web/20220928060455/https://n.news.naver.com/mnews/article/001/0004386255?sid=100|archivedate=28 September 2022|accessdate=28 September 2022|author=}}</ref> On 15 November 1999, Hyundai Precision Industry signed an estimate of 1 trillion KRW contract to produce the K1A1.<ref>{{Cite web |last=안 |first=승섭 |title=현대정공, 1조원 규모 K1A1전차 공급계약 |url=https://n.news.naver.com/mnews/article/001/0004561002?sid=101 |access-date=2022-09-25 |website=[[Naver News]] |language=ko}}</ref> The first K1A1 release ceremony was held on 12 October 2001. The tank weighs 53.2 t and has a length of 9.71 m (gun forward), and each tank costs 4.4 billion KRW with 67% localization rate by value.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/009/0000155877?sid=102|title=국산 K1A1 전차, 실전 배치|publisher=[[Yonhap News Agency]]|date=12 October 2001|archiveurl=https://web.archive.org/web/20220928231040/https://n.news.naver.com/mnews/article/009/0000155877?sid=102|archivedate=28 September 2022|accessdate=28 September 2022|author=Baek Soon-ki}}</ref><ref name="K1A1 release"/>

Unlike the K1, the newly upgraded design was made only by Korean engineers. Originally, GDLS wanted to participate in the K1 series to maintain its level of influence, and it proposed a partnership for the project due to concerns about Koreans lacking such skills. However, South Korean engineers declined the offer, and decided to take full responsibility on the project even if it failed, because they could learn about the main battle tank throughout the process and to maximize localization by reducing the technological reliance from GDLS. In the end, GDLS transferred the TDP, and sent a small team of engineers to South Korea for a 50-man-day contract, but the contract was never needed.<ref name="K1 interview"/><ref name="K1A1 interview"/>

Despite the similar look, the K1A1 is made of completely different materials and carries more advanced subsystems.<ref name="K1 interview"/><ref name="K1A1 interview"/> The K1A1 can easily be distinguished from the K1 by the shape of the gun, location of the co-axial machinegun, shape of the commander's sight, and overall angular shape of the turret (the K1A1 has more curved surfaces than the K1). The 120&nbsp;mm smoothbore gun of the K1A1 is thicker than the K1's 105&nbsp;mm rifled gun and has a thicker thermal sleeve a third of the way from the base of the gun. The co-axial machinegun on the K1A1 is located at a much higher point compared to the K1. The K1A1 also features a somewhat cone-shaped day/night KGPS compared to the day-only sight of the K1, which has a plain, tube-like appearance to it.

{| class="wikitable"
|+ K1 & K1A1 comparison (1996)
|- style="text-align:center;"
! style=width:140px | Variants
! style=width:28% | K1 (early)
! style=width:28% | K1 (late)
! style=width:28% | K1A1
|- style="text-align:center;"
! Main gun
| colspan=2 | [[Royal Ordnance L7|KM68A1 105 mm rifled]] (47 rounds)
| [[M256 (tank gun)|KM256]] 120&nbsp;mm smoothbore (32 rounds)
|- style="text-align:center;"
! Firepower (estimate)
| colspan=2 | K270 APFSDS, 300&nbsp;mm penetration at 2.5&nbsp;km
| K276 APFSDS, 600&nbsp;mm penetration at 2.5&nbsp;km
|- style="text-align:center;"
! Commander's sight
| colspan=2 | VS580-13
| KCPS
|- style="text-align:center;"
! Gunner's sight
| GPSS
| GPTTS
| KGPS
|- style="text-align:center;"
! Protection (estimate)
| colspan=2 | [[Chobham armour|SAP]] 400–500&nbsp;mm vs KE
| KSAP 600&nbsp;mm vs KE
|- style="text-align:center;"
! Weight
| 51.1 t
| 51.5 t
| 53.2 t
|- style="text-align:center;"
|}

==== Firepower ====
The most important upgrade was switching the [[Tank gun|main gun]] from a 105&nbsp;mm KM68A1 [[Rifling|rifled]] (47 rounds) to a 120&nbsp;mm [[M256 (tank gun)|KM256]] smoothbore (32 rounds), which is produced under license by Hyundai Precision Industry (now [[Hyundai WIA]]), mounted on the domestically upgraded turret.<ref name="K1A1 interview"/> In addition, South Korea began to deploy K276 120&nbsp;mm [[armour-piercing fin-stabilized discarding sabot|armor-piercing fin-stabilized discarding sabot]] (APFSDS) ammunition with the most sophisticated [[tungsten]] heavy alloy [[Kinetic energy penetrator|penetrator]]s during that time, created after several technological breakthroughs that were new to the world. Benefiting from domestic tungsten processing technologies from abundant deposits,{{notetag|In South Korea's Gangwon province, there is the [[Sangdong mine|Sangdong Mine]], the world's largest tungsten mine.}} Korean engineers invented a self-sharpening process on the tungsten heavy alloy (a process which in the past was only achievable for [[depleted uranium]] (DU) penetrators) by applying [[microstructure]] control and multi-stage cyclic [[Heat treating|heat treatment]]. The self-sharpening process was developed over four years between 1990 and 1993 with a 1.1 billion KRW budget.<ref>{{cite web|url=http://www.dapis.go.kr/journal/200204/j120.html|title=텅스텐중합금 관통자 기술현황|publisher=[[Agency for Defense Development]]|date=April 2002|archiveurl=https://web.archive.org/web/20041225223951/http://www.dapis.go.kr/journal/200204/j120.html|archivedate=25 December 2004|accessdate=25 December 2004|author=Hong Moon-hee}}</ref><ref name="ADD">{{Cite web |title=국방과학연구소 50주년 |url=https://www.add.re.kr/board?menuId=MENU02608 |access-date=2022-09-26 |website=www.add.re.kr |language=ko |archive-date=2022-09-26 |archive-url=https://web.archive.org/web/20220926042150/https://www.add.re.kr/board?menuId=MENU02608 |url-status=dead }}</ref> Most penetrators in the world receive a single heat treatment, while Korean penetrators are treated 20 times using the new technology, which increases [[Impact depth|impact]] toughness by 300%. The self-sharpening effect increases penetration by 8–16% compared to regular penetrators, and compensates for tungsten's previous material disadvantage against DU: without the new technology, a tungsten penetrator has 6–10% less penetration than a DU penetrator. Thus, the new technology provides [[firepower]] like of that of DU ammunition without the disadvantage of toxic DU particles.<ref name="K1 interview"/><ref>{{cite web|url=https://koreascience.kr/article/JAKO200141548511327.pdf|title=환경오염 문제가 전혀 없는 대 전차 탄용 텅스텐 중합금 재료 개발|publisher=Korea Defense Industry Association|date=1 August 2001|archiveurl=https://web.archive.org/web/20230410095910/https://koreascience.kr/article/JAKO200141548511327.pdf|archivedate=10 April 2023|accessdate=10 April 2023|author=[[Agency for Defense Development]]}}</ref><ref>{{cite web|url=https://www.reseat.or.kr/portal/cmmn/file/fileDown.do?menuNo=200019&atchFileId=7c05781b826b4406b74cf4cde48f3df2&fileSn=1&bbsId=|title=미세입자 텅스텐 중합금 관통자의 관통 성능과 셀프샤프닝 거동|publisher=[[Korea Institute of Science and Technology Information]]|date=22 November 2016|archiveurl=https://web.archive.org/web/20230506153830/https://www.reseat.or.kr/portal/cmmn/file/fileDown.do?menuNo=200019&atchFileId=7c05781b826b4406b74cf4cde48f3df2&fileSn=1&bbsId=|archivedate=6 May 2023|accessdate=6 May 2023|author=Heo Sun-moo}}</ref> South Korea holds related [[patent]]s on 6 other nations including [[Japan]], the [[United Kingdom]], and the United States,{{notetag|Three other nations are yet unspecified, but it was likely the major manufacturers during that time, which includes France, Germany, and Israel.}} and the penetrator manufacturing technology was on the [[United States Army|U.S. Army]] Science and Technology Master Plan (ASTMP) in 1997 and 1998 as a technology to acquire from outside the United States. Later, In 2009, the U.S. negotiated with the South Korean government to introduce penetrator technology, but the negotiations did not progress further because South Korea wanted to export only the [[Final product|finished product]]s of the penetrator technology through the U.S. Army's Foreign Comparative Testing (FCT){{notetag|The Foreign Comparative Testing (FCT) is one of the U.S. Department of Defense's procurement programs introduced in 1989 to supply superior overseas items or technologies that are not produced in the United States more quickly and economically.}} program.<ref name="K1 interview"/><ref>{{cite web|url=http://www.fas.org/man/dod-101/army/docs/astmp/aE/E2O1.htm|title=Annex E. International Armaments Strategy Army Science and Technology Master Plan (ASTMP 1997)|publisher=[[Federation of American Scientists]]|date=1997|archiveurl=https://web.archive.org/web/20010713020240/http://www.fas.org/man/dod-101/army/docs/astmp/aE/E2O1.htm|archivedate=13 July 2001|accessdate=10 April 2023|author=[[United States Department of the Army]]}}</ref><ref>{{cite web|url=http://www.fas.org/man/dod-101/army/docs/astmp98/eb15.htm|title=1998 Army Science and Technology Master Plan|publisher=[[Federation of American Scientists]]|date=1998|archiveurl=https://web.archive.org/web/20000929233015/http://www.fas.org/man/dod-101/army/docs/astmp98/eb15.htm|archivedate=29 September 2000|accessdate=10 April 2023|author=[[United States Department of the Army]]}}</ref>

==== Electronics and sensors ====
The systems were upgraded from 16-bit to 32-bit and were designed using upgraded computers including 32-bit digital ballistic calculators.<ref name="K1A1 release">{{Cite web |title=한국형 K1전차 성능 개량 K1A1 전차개발 출고식 |url=https://n.news.naver.com/mnews/article/020/0000089881?sid=100 |access-date=2022-09-24 |website=[[Naver News]] |language=ko}}</ref>

The new gunner's sight KGPS consists of a stabilization device that allows better accuracy for aiming and shooting during maneuvers, a thermal imaging device and a daytime optical device for night and day observation and a laser rangefinder that measures the range of the captured target. The sharpness and magnification of the thermal imager and daytime optical system have been increased, making it possible to observe and identify the target from a greater distance. In particular, the screen display method of the thermal imager has been improved for enhanced night combat capability. The laser rangefinder uses an eye-safe Raman laser, which gives excellent distance measurement ability while providing crew safety during crew training. In addition, the sight has a recording feature for the gunner to check the location of the aiming point during actual shooting or non-shooting training, enhancing the training effect and verifying the results. The thermal imaging device can be operated independently for convenience, thus allowing the tank to shoot even if the imager malfunctions.  The daytime optical system image is displayed in natural color, making it convenient to observe. The power consumption is reduced by about 40% compared to the previous model, which increases operational time with the engine off to maximize stealth kill.<ref name="GPS"/><ref name="KGPS"/><ref name="K1A1 interview"/> It has a daytime magnification of 1 to 10 times and a far-infrared thermal magnification of 3 to 10 times.<ref name="ADD"/>

The new commander's sight KCPS (Korean Commander's Panoramic Sight) was developed in 1999 and has a thermal sight for night operation.<ref>{{Cite web |title=155mm 자주포등 5건 최우수방산개발품 선정 |url=https://n.news.naver.com/mnews/article/001/0004499076?sid=100 |access-date=2022-09-24 |website=[[Naver News]] |language=ko}}</ref> However, both the KGPS and KCPS heavily rely on foreign parts and were reported to have an average localization rate of 27.6% in the year 2004.<ref>{{Cite web |title=삼성탈레스 국방위 국감 |url=https://n.news.naver.com/mnews/article/028/0000082208?sid=102 |access-date=2022-09-24 |website=[[Naver News]] |language=ko}}</ref>

==== Protection ====
The SAP was changed to a more protective Korean Special Armor Plate (KSAP)<ref name="Samyang Comtech">{{cite web|url=http://samyangct.com/eng/lab/?ckattempt=1|title=Special Armor Plate for K1A1 Tank, K2 Tank, Altay Tank|publisher=[[Samyang Comtech]]|date=|archiveurl=https://archive.today/20220902201337/http://samyangct.com/eng/lab/?ckattempt=1|archivedate=2 September 2022|accessdate=2 September 2022|author=}}</ref> as well as switching American RHA to Korean domestic armor steel.<ref>{{cite web|url=http://kidet.or.kr/webzine/2011/09.php|title=K계열 전차 장갑의 성능개량 필요성과 기술추세|publisher=The Korean Institute of Defense Technology|date=November 2020|archiveurl=https://web.archive.org/web/20210419122250/http://kidet.or.kr/webzine/2011/09.php|archivedate=19 April 2021|accessdate=19 April 2021|author=Seo Ho-geun}}</ref> Although the exact specification is classified, it was reported that the KSAP provides a protection level of 600&nbsp;mm against KE ammunition for frontal armor.<ref name="k1 armor"/><ref name="K1A1 interview"/> In addition, the exterior of the K1A1 has [[Nut (hardware)|nuts]] that were not seen on the K1, hinting at a structural difference from the previous version. This is different from the way Americans installed and welded the SAP directly to prevent Koreans from technically accessing the armor during the K1 production.{{citation needed|date=October 2024}}{{notetag|Later produced batch of the K1 also shows nuts on the exterior, but there is no direct evidence of changing armor type.}} Moreover, a captain of the ROK Army Armor School mentioned the combination of [[Reactive armour|explosive reactive armor (ERA)]] with composite material being used for the armor of the K1A1.<ref>{{Cite web |title=우리는 고구려 철갑기병 후예 |url=https://kookbang.dema.mil.kr/newsWeb/20100721/2/BBSMSTR_000000010058/view.do |access-date=2022-09-24 |website=국방일보}}</ref> In 1996, South Korea acquired a 1,250&nbsp;hp variant of the Russian domestic specification T-80U tank along with [[Kontakt-5]] ERAs, and the T-80U contributed to developing Korean domestic ERAs and enhancing armor technology.<ref>{{Cite web |title=차관급 다수 편성, 대외 협력시 격 더 올라가 |url=https://kookbang.dema.mil.kr/newsWeb/20190527/1/BBSMSTR_000000010376/view.do |access-date=2022-09-24 |website=국방일보 |archive-date=2022-12-11 |archive-url=https://web.archive.org/web/20221211091324/https://kookbang.dema.mil.kr/newsWeb/20190527/1/BBSMSTR_000000010376/view.do |url-status=dead }}</ref><ref>{{Cite web |title=두 개의 안테나·4색 위장 무늬... 디테일이 살아있다 |url=https://kookbang.dema.mil.kr/newsWeb/20210623/1/BBSMSTR_000000100121/view.do |access-date=2022-09-24 |website=국방일보 |archive-date=2022-12-11 |archive-url=https://web.archive.org/web/20221211091641/https://kookbang.dema.mil.kr/newsWeb/20210623/1/BBSMSTR_000000100121/view.do |url-status=dead }}</ref><ref>{{Cite web |date=2010-03-25 |title=[기획 한국군 무기 21] 국군이 보유한 러시아 전차 T-80U |url=https://nownews.seoul.co.kr/news/newsView.php?id=20100325601007 |access-date=2024-02-20 |website=나우뉴스 |language=ko}}</ref> Therefore, based on the available sources, the K1A1 is fitted with domestic armor, in which the technology has influence from the American M1 Abrams and the Russian T-80U, and ERAs are located behind the outer shell of the tank.

==== Mobility ====
Both the torsion bar and hydropneumatic suspension were enhanced to withstand the recoil of the new 120&nbsp;mm cannon. The vehicle can move at a speed of 65&nbsp;km/h.<ref name="K1 interview"/><ref name="K1A1 interview"/><ref name="K1A1 release"/>

=== K1A2 ===
In 2007, the Joint Chiefs of Staff, the Army, and Hyundai Rotem planned to develop an upgrade model of the K1A1 by installing C4I [[network-centric warfare]] capability by 2011. On 22 September 2008, the Defense Acquisition Program Promotion Committee approved the K1A1 upgrade plan to install a [[battlefield management system]], [[identification friend or foe]], driver's thermal sight, and front and rear surveillance cameras. The upgraded K1A1 tank is expected to increase cooperative combat capabilities with the [[K2 Black Panther|next generation tanks]] and [[K21|K21 infantry fighting vehicles]] through improved all-weather combat capabilities and battlefield information sharing functions. However, the JCS cut the air conditioner budget by 100% to reduce the defense budget by sacrificing the welfare of the soldiers, which was heavily criticized as the air conditioner is a part of the positive pressure system that allows tank crews to operate in contaminated zones without wearing a gas mask.<ref>{{Cite web |date=2008-07-23 |title=사거리 60㎞ 다연장로켓 2013∼2014년 양산 계획 |url=https://www.segye.com/view/20080722003437 |access-date=2024-02-13 |website=[[Segye Ilbo]] |language=ko}}</ref><ref>{{Cite web |last=이 |first=현준 |title=사정거리 60km 이상 다련장로켓 국내 개발 |url=https://n.news.naver.com/mnews/article/003/0002202871?sid=100 |access-date=2024-02-13 |website=[[Naver News]] |language=ko}}</ref><ref>{{Cite web |last=박 |first=성진 |date=2009-12-03 |title=국산 전차 에어컨 "달아, 말아" |url=https://www.khan.co.kr/politics/defense-diplomacy/article/200912031813595 |access-date=2024-02-19 |website=[[Kyunghyang Shinmun]] |language=ko}}</ref><ref>{{Cite web |date=2009-12-02 |title=Soldiers Suffer Heat in Tanks |url=https://www.koreatimes.co.kr/www/nation/2024/02/205_56568.html |access-date=2024-02-19 |website=[[The Korea Times]] |language=en}}</ref>

On 12 September 2024, the [[Defense Acquisition Program Administration]] (DAPA) announced the completion of the K1A2 program and the achievement of full operational capability. The K1A2 was produced in four batches. The installation of a battlefield management system improved the previous analog communication to a digital form which has enabled digital map-based information sharing and visualization of battlefield situations for K1A2 crews. By applying the ground tactical data link (KVMF), a standardized specialized transmission and reception system, the tanks will be able to exchange tactical information between ground weapon systems quickly and accurately.<ref name="DAPA K1A2">{{Cite web |last=국방일보 |title=K1A2 전차 전력화 완료&hellip;전장 가시화 능력 향상 |url=https://kookbang.dema.mil.kr/newsWeb/20240913/3/ATCE_CTGR_0010020000/view.do |access-date=2024-09-20 |website=국방일보 |language=ko}}</ref><ref>{{Cite web |date=2024-09-13 |title=K1A2전차 양산계약 및 성능개량에 따른 공급량, 육군 부대에 인도 완료 |url=https://www.gukjenews.com/news/articleView.html?idxno=3090025 |access-date=2024-09-20 |website=국제뉴스 |language=ko}}</ref>

== Operational history ==
On 19 June 1995, the United States and South Korea agreed upon exporting the K1 to third countries during defense talks. Hyundai Precision Industry planned to sell 70 tanks to [[Malaysia]]. The price of the K1 was increased to $2.8 billion KRW in 1995.{{notetag|Presumably batch 3 price.}}<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003996055?sid=102|title=한국형 K-1전차, 제3국 수출 합의|publisher=[[Yonhap News Agency]]|date=19 June 1995|archiveurl=https://web.archive.org/web/20230128013741/https://n.news.naver.com/mnews/article/001/0003996055?sid=102|archivedate=28 January 2023|accessdate=28 January 2023|author=}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0003899162?sid=101|title=현대정공 K-1전차 수출 추진|publisher=[[Yonhap News Agency]]|date=10 July 1995|archiveurl=https://web.archive.org/web/20230128014243/https://n.news.naver.com/mnews/article/001/0003899162?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004072415?sid=100|title="방산업체 高價무기 수출 3년간 전무"|publisher=[[Yonhap News Agency]]|date=14 October 1996|archiveurl=https://web.archive.org/web/20230128015509/https://n.news.naver.com/mnews/article/001/0004072415?sid=100|archivedate=28 January 2023|accessdate=28 January 2023|author=Sung Ki-hong}}</ref> The K1 was displayed in Malaysia at DSA 1996 on 23–26 April 1996.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004131834?sid=102|title=말레이시아 防産전시회에 한국관설치|publisher=[[Yonhap News Agency]]|date=22 April 1996|archiveurl=https://web.archive.org/web/20230128020118/https://n.news.naver.com/mnews/article/001/0004131834?sid=102|archivedate=28 January 2023|accessdate=28 January 2023|author=}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004078023?sid=101|title=<焦点> 한국의 방위산업|publisher=[[Yonhap News Agency]]|date=22 October 1996|archiveurl=https://web.archive.org/web/20230128021701/https://n.news.naver.com/mnews/article/001/0004078023?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Moon Byung-hoon}}</ref> To suit the jungle environment of Malaysia, Hyundai suggested a 47.9 t variant '''K1M''' based on the K1; the tank carries a total of 41 rounds and is equipped with KGPS for the gunner's sight and an [[Overpressure (CBRN protection)|overpressure device]] for CBRN protection. The K1 competed against the Polish [[PT-91 Twardy]] of [[Bumar-Labedy]] and Ukrainian [[T-84]] of [[Kharkiv Morozov Machine Building Design Bureau|KMDB]]. Initially, the K1 was favored by Malaysia, but the high price and Malaysia's economic crisis caused by the [[1997 Asian financial crisis]] led to the selection of the Polish PT-91.<ref>{{cite web |url=https://n.news.naver.com/mnews/article/001/0004091376?sid=101|title=대외경제조정위원회 개최|publisher=[[Yonhap News Agency]]|date=6 December 1996|archiveurl=https://web.archive.org/web/20230128024859/https://n.news.naver.com/mnews/article/001/0004091376?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Kim Chang-hoi}}</ref><ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004392737?sid=102|title=<국감현장>-국방위|publisher=[[Yonhap News Agency]]|date=6 November 1998|archiveurl=https://web.archive.org/web/20230128025509/https://n.news.naver.com/mnews/article/001/0004392737?sid=102|archivedate=28 January 2023|accessdate=28 January 2023|author=Jung Hak-gu}}</ref><ref name="K1M"/>

In March 1996, LG Cable developed the K1 MBT detachable pad track to replace the locally produced American M88A1 integral pad track.<ref name="track shoe">{{Cite web |title=LS mtron Track Shoes |url=http://www.lstrackshoe.co.kr/company/history.html |access-date=2024-02-20 |website=www.lstrackshoe.co.kr}}</ref>

On 7 June 1999, Hyundai Precision Industry announced to co-develop the K1 tank simulator for weaponry with the ADD to lower the training cost.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004542561?sid=101|title=현대정공, 전차포술 모의훈련장비 개발 착수|publisher=[[Yonhap News Agency]]|date=7 June 1999|archiveurl=https://web.archive.org/web/20230128032817/https://n.news.naver.com/mnews/article/001/0004542561?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Lee Kyung-wook}}</ref> On 19 February 2001, Hyundai Mobis (formerly Hyundai Precision Industry) announced that the simulator was completed and supplied to the military on 19 February 2001. Simulators are expected to decrease training costs from 20 billion KRW to 1.4 billion KRW per 1,000 trainees every year.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/008/0000052608?sid=101|title=[거래소] 현대모비스 "전차 포술 모의훈련기 개발·납품"|publisher=Money Today|date=19 February 2001|archiveurl=https://web.archive.org/web/20230128034518/https://n.news.naver.com/mnews/article/008/0000052608?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Park Jae-bum}}</ref>

On 28 October 1999, [[Samsung Electronics]] and [[Thomson-CSF]] agreed to create a joint venture with each company investing and holding 50% of the shares. Thomson-CSF will receive technology transfer of Samsung's defense products such as communication equipment, satellite communication systems, and terminals, fire control systems, detection and tracking devices, radar guidance equipment, and gunner's sight (KGPS), while Samsung will gain access to Thomson-CSF's network for overseas exports.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0004478581?sid=101|title=삼성전자-톰슨, 방산 합작계약|publisher=[[Yonhap News Agency]]|date=28 October 1999|archiveurl=https://web.archive.org/web/20230128035148/https://n.news.naver.com/mnews/article/001/0004478581?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Park Sang-hyun}}</ref> In February 2000, Samsung Thomson-CSF was created, and it was renamed Samsung Thales on 26 February 2001.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/009/0000116748?sid=101|title=[인터뷰] 박태진 삼성탈레스 사장|publisher=[[Maeil Business Newspaper]]|date=13 May 2001|archiveurl=https://web.archive.org/web/20230128035703/https://n.news.naver.com/mnews/article/009/0000116748?sid=101|archivedate=28 January 2023|accessdate=28 January 2023|author=Choi Eun-soo}}</ref>

On 27 February 2003, Ssang Yong Information and the ADD developed an [[Interactive electronic technical manual|IETM (interactive electronic technical manual)]] in four [[CD-ROM]]s that contain twenty books of a technical manual for the K1A1 using domestically developed software for the first time.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/031/0000019117?sid=105|title=쌍용정보, 국방 기술교범 디지털화 SW 개발|publisher=inews24|date=27 February 2003|archiveurl=https://web.archive.org/web/20230128040451/https://n.news.naver.com/mnews/article/031/0000019117?sid=105|archivedate=28 January 2023|accessdate=28 January 2023|author=Lee Kyun-sung}}</ref> On 26 September, the ADD announced the development of insensitive gunpower that does not explode in shock, fire, or heat that can occur in the transport, storage, and operation of warheads and ammunition.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/001/0000466999?sid=102|title=차기전차용 열상센서.둔감화약 개발|publisher=[[Yonhap News Agency]]|date=26 September 2003|archiveurl=https://web.archive.org/web/20230128041231/https://n.news.naver.com/mnews/article/001/0000466999?sid=102|archivedate=28 January 2023|accessdate=28 January 2023|author=Lee Sang-heon}}</ref>

In September 2003, [[Typhoon Maemi]] caused seawater damage to the domestic circular cooler prototype for K1 tanks and its test and evaluation facilities at Hanjo Company in Busan. The STX engine, which had joined with Hanjo to localize core components since 2002, also dispatched a team to recover the sight and requested an extension of the project to the Ministry of Defense as the due date was only six months away. Eventually, two companies restored damages in three months and completed product development in January 2004. The localized circular cooler costs 26 million KRW, less than the import variant, which costs 43 million KRW.<ref>{{Cite web |title=STX엔진-한조, 태풍매미도 못꺾은 '국산화 집념' |url=https://n.news.naver.com/mnews/article/009/0000382409?sid=101 |access-date=2024-02-19 |website=[[Naver News]] |language=ko}}</ref>

On 21 October 2004, it was revealed that South Korea was developing [[depleted uranium]] tank munitions between 1983 and 1987. South Korea eventually halted the development after the United States learned about the project in 1987.<ref>{{cite web|url=https://n.news.naver.com/mnews/article/047/0000052071?sid=100|title="원자력연, 80년대 열화우라늄탄 개발"|publisher=[[OhmyNews]]|date=21 October 2004|archiveurl=https://web.archive.org/web/20230128044731/https://n.news.naver.com/mnews/article/047/0000052071?sid=100|archivedate=28 January 2023|accessdate=28 January 2023|author=Kwon Bak-hyowon}}</ref>

In March 2005, LS Cable (formerly LG Cable) developed the K1A1 MBT detachable pad track to replace the previous generation model for both K1 and K1A1.<ref name="track shoe"/>

On 26 June 2008, the Defense Acquisition Program Promotion Committee approved mass production of the KCPS for K1 tanks until 2014 to provide thermal sight for tank commanders.<ref>{{Cite web |last=송 |first=한진 |title=李 국방, 제28회 방위사업추진위원회 주재 |url=https://n.news.naver.com/mnews/article/003/0002160787?sid=100 |access-date=2024-02-11 |website=[[Naver News]] |language=ko}}</ref>

On 19 March 2009, the STX Engine and the MTU signed a MOU to transfer the ownership of the MB871Ka-501 diesel engine. The STX Engine had achieved 80% localization rate prior to the MOU, and gained right to manufacture, maintain, and sell the engine.<ref>{{Cite web |date=2009-03-19 |title=STX엔진, K1전차 엔진 독점권 인수 |url=https://news.mt.co.kr/mtview.php?no=2009031908480358603 |access-date=2024-02-11 |website=Money Today |language=ko}}</ref><ref>{{Cite web |date=2009-03-19 |title=STX엔진, 獨 전차 디젤엔진 소유권 확보 |url=https://www.asiae.co.kr/article/2009031908240943129 |access-date=2024-02-11 |website=아시아경제 |language=ko}}</ref>

On 6 September 2009, North Korea released the floodgates of Hwanggang Dam at dawn without warning, leaving six South Korean civilians missing and one K1 tank trapped in the swollen river, which was rescued after hours.<ref>{{Cite web |date=2009-09-07 |title=北 예고없는 '물폭탄'… 야영객 6명 실종 |url=https://www.donga.com/news/article/all/20090907/8806170/1 |access-date=2024-02-19 |website=[[The Dong-a Ilbo]] |language=ko}}</ref>

On 23 October 2009, i3system, inc. developed a domestic infrared detector after 3 years of research. The infrared detector detects infrared rays emitted from an object even when there is no light and converts them into a two-dimensional image signal of 320×240 pixels. Until now, infrared detectors have only been produced in five countries, including the U.S. and France, and have been expensive equipment costing 25 million KRW each. Infrared detectors were tested and determined to be suitable for military use in April and May and will be deployed to K1 tank thermal sights and artillery observation equipment from 2010, and will be applied to guided weapons and K21 IFV sights afterward.<ref>{{Cite web |date=2009-10-23 |title=아이쓰리시스템 '적외선검출기' 국내 최초 개발 |url=https://www.asiae.co.kr/article/2009102309234180812 |access-date=2024-02-19 |website=아시아경제 |language=ko}}</ref>

On 6 August 2010, during a live firing exercise at [[Paju]], a round exploded in the barrel of a K1's 105&nbsp;mm gun, destroying the gun but leaving the crew uninjured.<ref>{{Cite web |date=2010-09-06 |title=육군주력 K1전차 포신 폭발 |url=https://www.seoul.co.kr/news/newsView.php?id=20100906006012 |access-date=2024-02-11 |website=[[Seoul Shinmun]] |language=ko}}</ref> It was the ninth incident since the operation of the K1 tanks: 1985 (1, XK1), 1987 (2), 1991 (1), 1994 (1), 2002 (1), 2009 (2), and 2010 (1), of which the previous eight were caused by foreign substances within the barrel according to the Agency for Defense Development, the Defense Agency for Technology and Quality, and the manufacture.<ref>{{Cite web |last=김 |first=귀근 |title=K1전차 포신파열 사고 9회..원인은 못밝혀 |url=https://n.news.naver.com/mnews/article/001/0004642540?sid=100 |access-date=2024-02-11 |website=[[Naver News]] |language=ko}}</ref><ref>{{Cite web |last=김 |first=호준 |title="K-1 전차 포신파열 사고원인 이물질로 추정" |url=https://n.news.naver.com/mnews/article/001/0004658095?sid=100 |access-date=2024-02-11 |website=[[Naver News]] |language=ko}}</ref> However, the Army reinvestigated and claimed the August 2009 incident was due to fatigue failure caused by long usage of the barrel, which is a human error for failing inspection.<ref>{{Cite web |date=2010-09-15 |title=K-1전차 포신파열은 정비불량탓 |url=https://www.donga.com/news/article/all/20100915/31200276/1 |access-date=2024-02-11 |website=[[The Dong-a Ilbo]] |language=ko}}</ref> On 19 November, the investigation team concluded that the August 2010 barrel burst was caused by the tensile residual stress remaining in the metal during the processing stage and a long period of use and exposure to corroded environments such as humidity, oxygen, and temperature. Therefore, the Army will conduct a detailed inspection of all K1 tank guns, use specialized tools to conduct preliminary inspections, and carry out the procedure for barrel cleaning before firing. In the long run, the Army will request external agencies to establish the acceptance criteria for microcracks and manage the cannon production process more thoroughly.<ref>{{Cite web |date=2010-11-20 |title=[사설] 설계결함·거짓정비… 軍需 환부 도려내라 |url=https://www.seoul.co.kr/news/newsView.php?id=20101120027010 |access-date=2024-02-11 |website=[[Seoul Shinmun]] |language=ko}}</ref><ref>{{Cite web |date=2010-11-19 |title="불량 K계열 장비, 부실 제조와 기강 해이의 결합" |url=https://www.newdaily.co.kr/site/data/html/2010/11/19/2010111900039.html |access-date=2024-02-22 |website=뉴데일리 |language=ko}}</ref>

On 15 September, the Ministry of Defense revealed that the LSG 3000 transmission used for the K1 and the K1A1 has defects, and the production of the K1A1 has been suspended since February and expects a delay of one year until fixing the problem. In 2005, the Army checked 1,329 vehicles and found 102 with defective transmissions caused by iron powder and broken gear pieces in transmission oil. 77 vehicles with minor problems were fixed at the base while 25 vehicles with major issues had to be repaired at the maintenance depot. The initial solution was to install magnetic drainage plugs and oil drainage ports to collect iron powders but did not fix the source of the problem. Between 2005 and 2010, 189 additional vehicles were repaired after experiencing same transmission problem. On 30 December 2010, the Defense Acquisition Program Promotion Committee resumed the production of the K1A1 before the transmission durability test results, with a condition for recalling all vehicles if found to be manufacturer's fault, due to [[2010 Yeonpyeong bombardment|changes in national security situation]]. In April 2011, the Korea Institute of Machinery and Materials, which conducted durability tests of the K1A1 tank since June 2010, concluded that the right output bearing and fan housing were damaged during the basic steering durability test due to a design defect in the transmission itself.<ref>{{Cite web |date=2010-09-15 |title=주력무기 K계열 무엇이 문제인가 (1) 현대로템의 K1, K1A1전차 |url=https://www.asiae.co.kr/article/2010091510451223139 |access-date=2024-02-11 |website=아시아경제 |language=ko}}</ref><ref>{{Cite web |title=K계열 국산무기, 설계 결함·이물질 때문 |url=https://www.konas.net/article/article.asp?idx=22987 |access-date=2024-02-11 |website=www.konas.net |language=ko}}</ref><ref>{{Cite web |last=홍 |first=장기 |title=K계열 전차 변속기 6년간 291대 결함 |url=https://n.news.naver.com/mnews/article/086/0002057196?sid=102 |access-date=2024-02-12 |website=[[Naver News]] |language=ko}}</ref><ref>{{Cite web |title="검증 안됐는데…" 변속기결함 K1A1전차 생산재개 |url=https://n.news.naver.com/mnews/article/003/0003766982?sid=100 |access-date=2024-02-12 |website=[[Naver News]] |language=ko}}</ref>

On 31 March 2011, the Army found an issue with 95 K1A1s with domestic fire detector, which replaced American counterpart that suspended production, activating fire extinguishing system when the tank fires to its left side. It was due to its excessive sensitivity (5 meters) that detected flame from gunfire, so the manufacturer adjusted to the American detector standard (2.5 meters).<ref>{{Cite web |last=박 |first=성진 |date=2011-08-16 |title=K1전차 훈련 중 오작동 97대 전량 리콜 |url=https://www.khan.co.kr/politics/defense-diplomacy/article/201108162300225 |access-date=2024-02-12 |website=[[Kyunghyang Shinmun]] |language=ko}}</ref><ref>{{Cite web |date=2011-08-17 |title="K1 전차가 리콜된 게 아니구요…." |url=https://www.newdaily.co.kr/site/data/html/2011/08/17/2011081700015.html |access-date=2024-02-12 |website=뉴데일리 |language=ko}}</ref>

In December 2020, the ADD commenced a program to develop unmanned versions of the K1 tank and [[K9 Thunder]]. [[Hyundai Rotem]] was contracted to develop the unmanned tank by 2024.<ref>{{cite web|url=https://www.janes.com/defence-news/news-detail/south-korea-to-develop-unmanned-technologies-for-k1-mbt-and-k9-sphs|title=South Korea to develop unmanned technologies for K1 MBT and K9 SPHs|publisher=[[Janes Information Services]]|date=11 August 2020|archiveurl=https://web.archive.org/web/20230128050351/https://www.janes.com/defence-news/news-detail/south-korea-to-develop-unmanned-technologies-for-k1-mbt-and-k9-sphs|archivedate=28 January 2023|accessdate=28 January 2023|author=Dae Young Kim}}</ref><ref>{{cite web|url=https://www.janes.com/defence-news/news-detail/hyundai-rotem-aims-to-roll-out-unmanned-k1-mbt-testbed-by-2024|title=Hyundai Rotem aims to roll out unmanned K1 MBT testbed by 2024|publisher=[[Janes Information Services]]|date=6 January 2021|archiveurl=https://web.archive.org/web/20230128051118/https://www.janes.com/defence-news/news-detail/hyundai-rotem-aims-to-roll-out-unmanned-k1-mbt-testbed-by-2024|archivedate=28 January 2023|accessdate=28 January 2023|author=Dae Young Kim}}</ref>

== Variants and upgrades ==
[[File:2015 아덱스(ADEX) K1 교량전차 가설시범.jpg|thumb|right|A K1 AVLB deploying its bridge]]
[[File:2011.11.11 육군11사단 정비대대 전차정비 (7633936210).jpg|thumb|The K1 ARV being in use when replacing a tank engine]]

*'''ROKIT''': Acronym for the Republic of Korea Indigenous Tank. Experimental prototype by Chrysler Defense. 2 vehicles (PV-1 and PV-2) were produced.<ref name="MILP">{{cite web | url=https://milmag.pl/en/development-of-south-korean-tank-k1/ |title=Development of South Korean Tank K1 | date=8 February 2024 }}</ref>
*'''XK1''': Preproduction prototype by Hyundai Precision Industry. 5 vehicles were produced, and entered service in 1986.<ref name="MILP"/>
*'''K1''': First production variant. 1,027 units built between 1987 and 1997 (445 with GPSS and 582 with GPTTS) in 3 batches. To be upgraded to K1E1 by 2026.
**'''K1M''': Proposed export variant for Malaysia.<ref>{{cite web | url=https://premium.globalsecurity.org/military/world//rok/type-88-mbt.htm |title=Type 88 K1 Main Battle Tank &#91;Hyundai&#93; }}</ref>
**'''K1 PIP''': Replaced VS580-13 with KCPS.<ref>{{Cite web |date=2010-02-24 |title=베레모 쓴 최강 기갑부대 훈련은 |url=https://www.asiae.co.kr/article/2010021610325640645 |access-date=2024-02-19 |website=아시아경제 |language=ko}}</ref>
***'''K1E1''': Further upgraded K1. Production began in December 2013, and the first K1E1 rolled out on 7 July 2014. The upgrade will be similar to that of K1A2. All K1 will be upgraded to K1E1 by 2026.<ref name="The Korea Defense Daily">{{cite web|url=http://kookbang.dema.mil.kr/kookbangWeb/view.do?parent_no=82&bbs_id=BBSMSTR_000000000138&ntt_writ_date=20140522|title=2022년까지 K1A1→ K1A2로 개량|publisher=The Korea Defense Daily|access-date=21 May 2014|language=ko|archive-url=https://web.archive.org/web/20170305025249/http://kookbang.dema.mil.kr/kookbangWeb/view.do?parent_no=82&bbs_id=BBSMSTR_000000000138&ntt_writ_date=20140522|archive-date=5 March 2017|url-status=live}}</ref> The name was inherited from the K1A1 prototype, the K1E1.<ref name="K1A2, K1E1">{{cite web|url=https://blog.hyundai-rotem.co.kr/444|title=K1A2·K1E1, 성능개량으로 강해지는 전차!|publisher=Hyundai Rotem|date=22 May 2020|archiveurl=https://web.archive.org/web/20220616104131/https://blog.hyundai-rotem.co.kr/444|archivedate=16 June 2022|accessdate=16 June 2022|author=}}</ref>
***'''K1E2''': As of August 2018, the K1E2 type is planned to be improved. It is expected to be upgraded to a large-scale repair (renovation) in 2024. The main improvement point is the replacement of the new armored upgrading of the protection, installation of the positive pressure device, acceleration of 10% upgrade (1200&nbsp;hp engine to 1320&nbsp;hp) or change 1500&nbsp;hp engine, Introduction of RWS, etc.<ref name="Seoul Economy">{{cite web|url=https://www.sedaily.com/NewsView/1S3B2XO27V|title=(권홍우 선임기자의 무기 이야기)K1전차 개량 '환갑'까지...2024년부턴 에어컨도|date=10 August 2018|publisher=Seoul Economy|access-date=10 August 2018|language=ko|archive-url=https://web.archive.org/web/20180814230120/http://www.sedaily.com/NewsView/1S3B2XO27V|archive-date=14 August 2018|url-status=live}}</ref>
*'''K1A1''': First major enhanced variant. 484 units built between 1999 and 2011 in 2 batches.<ref>{{Cite web |last=김 |first=상범 |title="국방부 국회승인 안거치고 26개사업 전력증강비 12조 늘려" |url=https://n.news.naver.com/mnews/article/086/0000006510?sid=100 |access-date=2022-12-08 |website=[[Naver News]] |language=ko}}</ref> All vehicles received A2 upgrade as of September 2024.<ref name="DAPA K1A2"/>
**'''K1A2''': Upgraded K1A1. Originally named as K1A1 PIP. Developed from 2008 to 2010, and mass-production started in 2012. First upgraded vehicle was rolled out on 20 December 2013. Technology benefit from [[K2 Black Panther]] has been applied to this model. It features additional systems such as a [[Battlefield management system|battlefield control system]], [[Identification friend or foe|IFF system]], front and [[Backup camera|rear surveillance camera]] and [[navigation]] system. With its improved real-time information sharing, inter-combat vehicle operation, friendly fire prevention and driver operability.<ref name="DAPA K1A2"/>
***'''K1A2 PIP''': Upgraded K1A2. [[Positive pressure]] devices and [[air conditioning]], soft-kill [[active protection system]]s have been added.
*'''K1 ARV''': The K1 Armored Recovery Vehicle is based on the K1 tank. It has a crane, winch and dozer system built on the vehicle.<ref name="ARV">[http://www.globalsecurity.org/military/world/rok/k1-arv.htm K1 ARV.] {{Webarchive|url=https://web.archive.org/web/20080220041524/http://www.globalsecurity.org/military/world/rok/k1-arv.htm |date=2008-02-20 }} Retrieved on 9 January 2008.</ref> It was developed with assistance from Krupp [[Maschinenbau Kiel]] GmbH (now [[Rheinmetall Landsysteme]] GmbH) between 1988 and 1992, with first deployment in 1993.<ref name="ARV" />
*'''K1 AVLB''': The K1 Armoured Vehicle-Launched Bridge variant uses a scissor-type bridge system mounted on the chassis. It was developed from 1988 to 1992 with help from [[Vickers plc|Vickers Defense Systems]].<ref>[http://www.globalsecurity.org/military/world/rok/k1-avlb.htm K1 AVLB.] {{Webarchive|url=https://web.archive.org/web/20080220041334/http://www.globalsecurity.org/military/world/rok/k1-avlb.htm |date=2008-02-20 }} Retrieved on 9 January 2008.</ref>
*'''K600 Rhino CEV''': The K1 Combat Engineer Vehicle is based on the K1A1/A2 chassis, mounting a [[mine plough]], an excavator arm on the right side, and a lane marking system.  Development is expected to be completed in June 2018 and begin production in 2019.<ref>[http://www.shephardmedia.com/news/landwarfareintl/hyundai-rotem-advances-armoured-armada/ Hyundai Rotem advances armoured armada] {{Webarchive|url=https://web.archive.org/web/20151223044638/https://www.shephardmedia.com/news/landwarfareintl/hyundai-rotem-advances-armoured-armada/ |date=2015-12-23 }}{{Snd}} Shephardmedia.com, 22 October 2015.</ref><ref>{{cite web|url=https://www.janes.com/amp/update-hyundai-rotem-awarded-contracts-for-k600-cevs-k1e1-mbts/ZnlJK3dHVU9mZ28xajRJVkc5dVI5VFp1cVMwPQ2|title=Update: Hyundai Rotem awarded contracts for K600 CEVs, K1E1 MBTs|publisher=Jane's|date=2018-06-10|access-date=2023-05-29|archive-url=https://web.archive.org/web/20210112061003/https://www.janes.com/amp/update-hyundai-rotem-awarded-contracts-for-k600-cevs-k1e1-mbts/ZnlJK3dHVU9mZ28xajRJVkc5dVI5VFp1cVMwPQ2|archive-date=2021-01-12|url-status=live}}</ref>

== Operators ==
[[File:K1 operators.svg|thumb|400px|Map of operators of K1 or its variants]]

=== Current operators ===
<!--READ FIRST: This section is for cited entries only. Please do not add entries into this list without a citation from a reliable source. All entries without a citation will be removed. Thank you.-->
<!--READ FIRST: Please list operators in alphabetical. Thank you.-->

;{{flag|Republic of Korea}}
* [[Republic of Korea Armed Forces]] – Received 1,027 K1 between 1987 and 1997, and 484 K1A1 between 1999 and 2011.<ref name="K1M"/> All K1/K1A1 are being upgraded to K1E1/K1A2 variants.
** [[Republic of Korea Army]]
** [[Republic of Korea Marine Corps]]

== See also ==
* [[List of main battle tanks by generation]]
* [[List of main battle tanks by country]]

==Notes==
{{Notelist}}

{{NoteFoot}}

==References==
{{reflist}}

==External links==
{{commons category|K1 88 tanks}}
* [http://www.army-technology.com/projects/k1/ K1A1 Main Battle Tank Details]
*[http://www.rotem.co.kr/eng/main_html/business.asp?url=%222-6-1-M%22 K1A1 Tank Overview] {{Webarchive|url=https://archive.today/20121220011013/http://www.rotem.co.kr/eng/main_html/business.asp?url=%222-6-1-M%22 |date=2012-12-20 }} at [[Hyundai Rotem]] Website (Best viewed in [[Internet Explorer]]).
* [http://www.globalsecurity.org/military/world/rok/type-88-mbt.htm Type 88 K1 Main Battle Tank] at GlobalSecurity.org
* [http://www.globalsecurity.org/military/world/rok/k1a1.htm K1A1 Main Battle Tank] at GlobalSecurity.org
* [http://www.globalsecurity.org/military/world/rok/k1-pics.htm Photos] at GlobalSecurity.org
* [http://armour.ws/south-korean-k1-and-k1a1-mbt/ K1-K1A1 MBT] at Armour.ws

{{Cold War tanks|style=wide}}
{{Post-Cold War tanks|style=wide}}

[[Category:Main battle tanks of the Cold War]]
[[Category:Post–Cold War main battle tanks]]
[[Category:Main battle tanks of South Korea]]
[[Category:Military vehicles introduced in the 1980s]]
[[Category:ADD research and development projects]]