K21-105: A Very Light Medium Tank

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Welcome to the suggestion post for the South Korean K21-105! This vehicle is a South Korean-developed K21 IFV, but fitted with the Belgian John Cockerill company’s CT-CV 105HP turret. Since it uses a turret similar to that on the Swedish CV90105 XC-8, it has all the features one might want, including thermal imaging, a 105 mm gun capable of firing 105 mm tank rounds, and two-plane stabilization. The hull, as mentioned, is that of a South Korean K21, which is a solid vehicle in its own respect. That’s why to start, I’ll begin with the history of the K21 IFV, and how the K21-105 came to be. If you see anything that is incorrect, feel free to let me know. Let’s begin!



A K200 APC, which replaced the M113.

In 1981, a request was submitted by the Republic of Korea Army for a new infantry fighting vehicle, called KIFV, or Korean Infantry Fighting Vehicle. South Korea had been looking to replace its aging M113A1s ever since the end of the Vietnam War, where the vehicle’s thin armor was noted, despite a number of successful engagements. Development of the KIFV was taken over by the Agency for Defense Development, while production would be carried out by Daewoo Heavy Industries once development was complete. The goals for the vehicle were to create a cost-effective vehicle that was still capable of carrying troops and crossing shallow bodies of water if necessary. The KIFV was to be based on the chassis of the AIFV, American Infantry Fighting Vehicle, itself a development of the M113. One notable part of development that occurred was Doosan signing a license-production deal with the German MAN company for its D2848T engine for use in the KIFV. The vehicle was eventually approved, and production began in 1986, and continues to see service to this day under the name K200.

Despite the name KIFV, the K200 was actually more of an APC by definition, with the basic version only being equipped with a 12.7 mm machine gun. A design for an IFV with a 25 mm cannon had been planned for development in the 1970s, but this was scrapped because of a lack of budget. A July 1989 study on the necessary requirements for a program known as NIFV, Next Infantry Fighting Vehicle, concluded that the NIFV would need increased levels of protection, as well as increased firepower, notably anti-tank missiles. A couple of miniature models were presented in 1991 by the Agency for Defense Development, one armed with a 30 mm cannon, another with a 35 mm cannon. Development officially began in December 1999, with the NIFV now being known under another name, K300. In 2003, Doosan DST was contracted to produce a prototype vehicle for 77 billion KRW. Three prototypes would be delivered to the Republic of Korea Army in 2005. In November 2009, after nearly 10 years of development, production officially began on the NIFV, now known under another designation, K21.

A K21 IFV, developed as a replacement for the K200.

Since its introduction into service, the K21 has been selected for use in a 2013 joint development by the Belgian company CMI Defence and the developer of the K21, Doosan DST. This cooperation aimed to create an upgunned K21 fitted with CMI Defence’s XC-8 series of turrets, notably the 105 mm and 120 mm variants.

A scale model of Hanwha Defense’s K21-105 Medium Tank at the 2018 Asian Defence and Security Trade Show at the World Trade Center in Pasay, Metro Manila, Philippines.

A K21-105 on display at the Seoul International Aerospace & Defense Exhibition at Seoul Airport, 2017.

A K21 fitted with the Cockerill XC-8 120HP turret at ADEX 2013.

The purpose of the K21 with the XC-8 turret is for fire support for infantry against hard targets, that is, armored vehicles, IFVs, APCs, buildings, and fortifications. Though both vehicles have been showcased, the 105 mm variant, the K21-105, first officially revealed in 2014, has received more coverage. The Cockerill XC-8 105HP turret on the K21-105 uses a 105 mm gun that loads ammunition from a bustle autoloader, and can fire 105 mm NATO tank rounds, as well as the Ukrainian Falarick GLATGM. While the K21-105 would have a difficult time against modern main battle tanks, it is perfect for use against older tanks such as those used by North Korea. Although classed by some as a light tank, Hanwha Defense, previously Doosan DST, has marketed the K21-105 as a medium tank. Despite this, one country looking into it as part of a light tank procurement program is India, where the K21-105 could prove to be a counter to Chinese vehicles such as the ZTQ-15.

Some of the features and specifics on the Cockerill 105HP turret.

While the turret may have changed, the chassis has not. The K21 hull was designed to provide protection against 30 mm APDS rounds firing at the front of the vehicle, while the side is meant to protect against 14.5 mm AP rounds. The composite armor on the vehicle has been confirmed to feature S2-glass fibre and Alumina ceramic, as well as lightweight aluminum alloy. Mobility is helped by a 750 hp turbocharged Doosan D2840XLE V-10 diesel engine. This, combined with a weight of around 25 tons, allows the vehicle to go to a maximum speed of 70 km/h.

As of September 2022, the K21-105 is not known to have been sold to any countries, but nevertheless provides a competitive choice for any future potential customers.

A K21-105 being demonstrated.



  • Crew: 3
  • Weight: 25 t
  • Length: 8.5 m
  • Hull length: 7 m
  • Width: 3.4 m
  • Height: 3 m
  • Main armament: 105 mm L/50 rifled gun
  • Ammunition stowed: 40 rounds
  • First-stage ammunition stowage (autoloader): 10 rounds
  • Secondary armament: Coaxial 7.62 mm machine gun
  • Elevation range: -10° to 42°
  • Traverse range: 360°
  • Engine: Doosan D2840LXE 750 hp diesel engine
  • Maximum road speed: 70 km/h
  • Maximum amphibious speed: 7 km/h
  • Maximum range: 450 km





Video showcase from Hanwha Defense: