Fact Sheet

North Korea Submarine Capabilities

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North Korea Submarine Capabilities

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North Korea maintains one of the world’s largest submarine fleets, with estimates for the total fleet ranging from about 64 to 86 submarines. North Korea maintains approximately 40 Sang-O-class coastal submarines (SCC), 20 Romeo-class conventional submarines (SS), 20 Yugo- and Yono-class mini submarines (SSM), and a single diesel-electric ballistic missile submarine (SSB) known as the Gorae-class (a.k.a. “Sinpo-class”).1

Open source satellite analysis of North Korea’s Sinpo Naval Shipyard suggests that North Korea is developing a new SSB, known within U.S. intelligence circles as the Sinpo-C-class.2 Despite the size of North Korea’s submarine fleet, experts doubt that all of the country’s submarines are operational given the age of the vessels. The Korean People’s Navy (KPN) is the primary operator, with some assets falling under the control of North Korea’s primary foreign intelligence agency, the Reconnaissance General Bureau (RGB).3

Capabilities at a Glance

Total Submarines in Fleet: 82

  • Ballistic Missile Submarine (SSBNs): 2
  • Nuclear-Powered attack submarines (SSNs): 0
  • Diesel-electric attack submarines (SSKs): 0
  • Air-independent propulsion (AIP) enabled: 1
  • Coastal Submarines (SSCs): 40
  • Conventional Submarines (SS): 20
  • Mini Submarines (SSMs): 20

 

Submarines

 
 

North Korea’s Gorae-class (Sinpo-class) submarine, which was first spotted at the Sinpo South Naval Shipyard in July 2014.

 

History

North Korea’s use of submarines, particularly for the purposes of espionage and infiltration, has precipitated a number of crises on the Korean Peninsula since the 1953 armistice. In 1996, a Sang-O-class submarine operated by the RGB ran aground near the South Korean city of Gangneung. The crew attempted to escape back to North Korea on foot and an ensuing 49-day manhunt led to the capture or killing of every crew member, save one who was never found.4 In June 1998, a Yugo-class North Korean submarine became entangled in a fishing net in South Korean waters near the port of Sokcho: all crewmembers perished in an apparent murder-suicide that took place as the submarine was towed back to port.5 In November 1998, a North Korean mini submarine was spotted by South Korean patrol boats near Ganghwa Island and narrowly evaded interception by South Korean forces, causing embarrassment to North Korea.6

A serious naval incident occurred on 26 March 2010 with the sinking of the ROKS Cheonan. The Cheonan, a South Korean corvette with a crew of 104, was attacked and sunk off the coast of Baengnyeong Island, near the Northern Limit Line. An international investigation concluded that a North Korean mini submarine likely sunk the Cheonan in a torpedo attack.7 North Korea has vehemently denied the report’s conclusions, and no party has accepted responsibility for the attack.

Modernization and Current Capabilities

While North Korea’s submarine fleet is largely comprised of small coastal submarines suitable for coastal defense, infiltration, and espionage missions, the Gorae SSB program suggests North Korea has plans to develop a strategic force. An operational SSB and SLBM capability could provide North Korea with additional options for nuclear launch, and a hedge against destruction of its land-based nuclear systems.8 Given the Gorae’s reliance on diesel-electric engines and lack of an Air-Independent Propulsion (AIP) system, the submarine can only remain submerged for a few days. This limits the Gorae to an effective range of an estimated 1,500 nautical miles, holding South Korean and Japanese targets at risk but precluding its ability to attack U.S. mainland targets.9

In parallel with its SSB production, North Korea has also produced a solid-fuel SLBM, the Pukguksong-1, also called the KN-11. North Korea has built a submerged test barge to facilitate ejection tests without risking damage to North Korea’s lone ballistic missile submarine, and satellite imagery suggests a second test barge is under construction.10 The SLBM program progressed remarkably quickly. The first ejection test from a sea-based platform occurred in December 2014, and only about 20 months later North Korea successfully test-fired an SLBM from the Gorae SSB.11 All tests have been conducted near the eastern port of Sinpo on the Sea of Japan. 12 Subsequent tests of a larger solid-fueled missile, the Pukguksong-2, appear to involve a land-based variant of the Pukguksong-1 SLBM.13

 

North Korea’s SLBM Test Site, Sinpo South Naval Shipyard

 

Ship Biographies

Gorae-Class

North Korea possesses one Gorae-class ballistic missile submarine that was launched in March 2014. 14 The Gorae holds a crew of 35, features a top speed of 10 knots, is 66.75 meters long, and has a 6.7-meter-wide beam. It likely features diesel-electric propulsion, but does not feature an Air-Independent Propulsion (AIP) system. 15 This limits the Gorae’s capability as a survivable, second-strike nuclear deterrent, as it cannot remain submerged for more than a few days without surfacing. The Gorae appears capable of firing a single ballistic missile; it has been used as a test-fire platform for submarine-launched ballistic missiles (SLBMs), but it is unclear whether North Korea intends to deploy the Gorae as an operational system. 16

In late 2017, construction activity at North Korea’s Sinpo Shipyard led observers to believe that the country may be building a new SSB as a successor to the Gorae, called the Sinpo-C class within the U.S. intelligence community. 17 The new Sinpo-C class submarine may feature a wider range and be able to accommodate a more advanced SLBM. 18

Sinpo-C-Class

North Korea possesses one Sinpo-C class ballistic missile submarine. On 21 August 2020, the South Korean National Intelligence Service reported that construction of the Sinpo-C class submarine was completed. 19 It is estimated to be around 3000 tons with the capacity to carry three or four ballistic missiles, possibly the Pukguksong-3. It likely features diesel-electric propulsion, and is purported to feature an Air-Independent Propulsion (AIP) system. If confirmed this would make this the first KPN submarine with this technology. 20

Sang-O-Class and Sang-O II Class

North Korea possesses approximately forty Sang-O- and Sang-O II-class costal submarines. The Sang-O-class features a top speed of 9 knots, is 34 meters long, and has a 3.8-meter-wide beam. 21 The Sang-O II-class is slightly longer and faster than its predecessor. Its top speed is approximately 15 knots and is 39 meters long. 22 It likely features diesel-electric propulsion, but does not feature an Air-Independent Propulsion (AIP) system.

Romeo-Class

The KPN’s aging fleet of 20 Romeo-class submarines is in an unknown state of operational readiness. The vessels remain the KPN’s only submarines capable of long-range patrols. The KPN first acquired 7 Romeo-class submarines from China in the mid-1970s, and then began producing the submarines domestically from 1976 until 1995, when production shifted in favor of the Sang-O-class.23 Reports suggest that the KPN is seeking to acquire modern sonar and radar technology in order to retrofit some of the aging Romeo-class submarines. However, North Korea is also likely replacing many of these with newer Sang-O-class vessels. 24 The majority of the Romeo-class fleet seems to be stationed on North Korea’s east coast.

Yugo- and Yono-Class SSM

North Korea operates a significant number of mini submarines (SSM), referred to as the Yugo- and Yono-class. Estimates vary, but nearly 20 may be in service. 25 The KPN began building Yugo-class submarines based on Yugoslavian designs in the 1960s. The Yono-class appears to be an improvement of the Yugo model, although Yugo submarines are still produced.

Import-Export Behavior

Imports

The KPN first acquired 7 Romeo-class submarines from China in the mid-1970s, and then began producing the submarines domestically from 1976 until 1995, when production shifted in favor of the Sang-O-class.26

Exports

North Korea has reportedly exported both physical vessels and designs of the Yono-class submarine to Iran and Vietnam. Iran’s Ghadir-class submarines are remarkably similar to the Yono-class submarines.27

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Glossary

Ballistic missile
A delivery vehicle powered by a liquid or solid fueled rocket that primarily travels in a ballistic (free-fall) trajectory.  The flight of a ballistic missile includes three phases: 1) boost phase, where the rocket generates thrust to launch the missile into flight; 2) midcourse phase, where the missile coasts in an arc under the influence of gravity; and 3) terminal phase, in which the missile descends towards its target.  Ballistic missiles can be characterized by three key parameters - range, payload, and Circular Error Probable (CEP), or targeting precision.  Ballistic missiles are primarily intended for use against ground targets.
SSBN
Ship, Submersible, Ballistic, Nuclear: A hull classification for a submarine capable of launching a ballistic missile. The "N", or nuclear, refers to the ship's propulsion system. SSBN's are generally reserved for strategic vessels, as most submarine launched ballistic missiles carry nuclear payloads. A non-strategic vessel carries the designation SSN, or attack submarine.
Diesel-electric submarine
Diesel-electric submarine: A submarine with a diesel-electric transmission. Diesel-electric transmissions require access to oxygen for the diesel generator to charge the submarine’s batteries or drive the motor. This type of submarine is thus louder and must surface more frequently than a nuclear-powered submarine. A diesel-electric submarine can fire conventional cruise missiles against land targets, and in theory, can also carry nuclear-tipped cruise missiles. Diesel-electric submarines are significantly cheaper to build and purchase than nuclear-powered vessels, which makes them the vessel of choice for smaller navies.
Air Independent Propulsion Technology (AIP)
Air Independent Propulsion Technology (AIP): A propulsion system that uses liquid (or compressed) oxygen or hydrogen fuel cells, thereby allowing submarines to stay submerged for longer periods without the need for external sources of oxygen. This increased endurance also increases a submarine’s survivability.
Submarine-launched ballistic missile (SLBM)
SLBM: A ballistic missile that is carried on and launched from a submarine.
Air Independent Propulsion Technology (AIP)
Air Independent Propulsion Technology (AIP): A propulsion system that uses liquid (or compressed) oxygen or hydrogen fuel cells, thereby allowing submarines to stay submerged for longer periods without the need for external sources of oxygen. This increased endurance also increases a submarine’s survivability.
Deterrence
The actions of a state or group of states to dissuade a potential adversary from initiating an attack or conflict through the credible threat of retaliation. To be effective, a deterrence strategy should demonstrate to an adversary that the costs of an attack would outweigh any potential gains. See entries for Extended deterrence and nuclear deterrence.
Deployment
The positioning of military forces – conventional and/or nuclear – in conjunction with military planning.

Sources

  1. “North Korea – Navy,” Jane’s Sentinel Security Assessment, 21 March 2018, www.janes.com; Department of Defense, “Democratic People’s Republic of Korea 2015,” 5 January 2016.
  2. Ankit Panda, “The Sinpo-C-Class,” The Diplomat, 18 October 2017.
  3. Department of Defense, “Military and Security Developments Involving the Democratic People’s Republic of Korea 2015: A Report to Congress Pursuant to the National Defense Authorization Act for Fiscal Year 2012,” 5 January 2016, www.defense.gov.
  4. Harry P. Dies, Jr., “North Korean Special Operations Forces: 1996 Kangnung Submarine Infiltration,” Military Intelligence Professional Bulletin, October-December 2004, www.thefreelibrary.com.
  5. Don Kirk, “9 North Koreans Dead in Submarine,” The New York Times, 27 June 1998, www.nytimes.com.
  6. Sebastien Roblin, “A Short History of North Korea’s Long Mini-Submarine Spy Campaign,” War Is Boring, 25 March 2017, www.warisboring.com.
  7. The Joint Civilian-Military Investigation Group, “Investigation Result on the Sinking of ROKS ‘Cheonan,’” 20 May 2010, http://news.bbc.co.uk.
  8. Kathleen J. McInnis et. al, “The North Korean Nuclear Challenge: Military Options and Issues for Congress,” Congressional Research Service, 6 November 2017.
  9. “Sinpo/GORAE-class Ballistic Missile Sub,” www.globalsecurity.org.
  10. “North Korea Continues Work on Second Barge Used for SLBM Test,” 38 North, 28 September 2017, www.38north.org.
  11. H.I. Sutton, “North Korea’s Polaris: Gorae Class Ballistic Missile Submarine (Sinpo),” 27 August 2016, hisutton.com.
  12. “Chronology of North Korea’s Missile, Rocket Launches,” Yonhap News Agency, 5 April 2017, english.yonhapnews.co.kr.
  13. Ankit Panda, “It Wasn’t an ICBM, but North Korea’s First Missile Test of 2017 Is a Big Deal,” The Diplomat, 14 February 2017, www.thediplomat.com.
  14. “Gorae Class,” Jane’s Fighting Ships, 13 December 2016, www.janes.com; “North Korea – Navy,” Jane’s Sentinel Security Assessment, 21 March 2018, www.janes.com; Joseph S. Bermudez Jr., “North Korea’s Submarine Ballistic Missile Program Moves Ahead: Indications of Shipbuilding and Missile Ejection Testing,” 38 North, 16 November 2017, www.38north.org.
  15. “Gorae Class,” Jane’s Fighting Ships, 13 December 2016, www.janes.com.
  16. “North Korea’s Submarine Ballistic Missile Program Moves Ahead: Indications of Shipbuilding and Missile Ejection Testing,” 38 North, www.38north.com.
  17. John Schilling, “North Korea’s SLBM Program Progresses, but Still Long Road Ahead,” 38 North 26 August 2016, 38north.org; Department of Defense, “Democratic People’s Republic of Korea 2015”; Kyle Mizokami, “Everything You Need to Know: North Korea’s Submarine Fleet,” The National Interest, 1 August 2017.
  18. Ankit Panda, “The Sinpo-C Class,” The Diplomat, 18 October 2017, www.thediplomat.com.
  19. “North Korea – Navy,” Jane’s Sentinel Security Assessment, 21 March 2018, www.janes.com.; Yang Seung-sik, “N.Korea Expected to Launch New Submarine Soon,” The Chosunilbo, 21 August 2020, www.english.chosun.com.
  20. “Sang-O Class,” Jane’s Fighting Ships, 1 December 2016, www.janes.com. “Sang-O II (K-300) Class,” Jane’s Fighting Ships, 1 December 2016, www.janes.com.; Elizabeth Shim, “Report: North Korea completing work on new SLBM submarines,” United Press International, 14 September 2017, www.upi.com.
  21. “North Korea – Navy,” Jane’s Sentinel Security Assessment, 21 March 2018, www.janes.com., “Sang-O Class,” Military Factory, 9 August 2017, www.militaryfactory.com.
  22. “N.Korea Builds up Submarine Force,” The Chosunilbo, 21 March 2011, www.english.chosun.com.
  23. “Romeo (Project 033) Class,” Jane’s Fighting Ships, 8 March 2018, www.janes.com.
  24. “North Korea – Navy,” Jane’s Sentinel Security Assessment, 21 March 2018, www.janes.com.
  25. “Yugo Class,” Jane’s Fighting Ships, 2 December 2016, www.janes.com. “Yono (P4) Class,” Jane’s Fighting Ships, 20 July 2017, www.janes.com.
  26. “Romeo (Project 033) Class,” Jane’s Fighting Ships, 8 March 2018, www.janes.com.
  27. “Yono (P4) Class,” Jane’s Fighting Ships, 20 July 2017, www.janes.com.

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