- The conversion of an old submarine into an underwater nuclear weapon launch platform likely represents a relatively fast and economical way to establish a sea-based nuclear deterrence.
- If the DPRK converts its entire Type 033 fleet in the next ten years, the DPRK could have a submarine-based arsenal consisting of 20-200 nuclear weapons.
- The DPRK leader ordered the defence industry to increase efforts in building nuclear-powered submarines and to build various kinds of modern warships needed for coastal defence, maritime patrol duty and offensive operations that are powered by modern naval engines. The timeline for these projects is unknown.
- The nuclearization of the Korean People’s Army (KPA) Navy (KPAN) is in line with (1) the DPRK’s long-time effort to increase the number of nuclear weapons and diversify their means of delivery and (2) the development trajectory of a KPA that is increasingly centred around nuclear weapons.
- Arming the KPA Ground Force and the KPAN with nuclear weapons raises the possibility that the DPRK could eventually pursue a nuclear triad. However, there is no evidence the DPRK is currently pursuing this capability.
The views expressed in this post are those of the author and not necessarily those of the Open Nuclear Network or any other agency, institution, or partner.
Key Findings
The No. 841 Submarine
On 6 September 2023, the DPRK launched its first “tactical nuclear attack submarine” - the “No. 841 Hero Kim Kun Ok” - at Pongdae Submarine Factory in Sinpo, South Hamgyong province. The new submarine, rebuilt on the basis of a Chinese Type 033 diesel submarine, has a total of ten vertical missile launch tubes that can potentially accommodate both nuclear-armed short-range ballistic missiles and nuclear-armed land-attack cruise missiles.
The KPAN has approximately 20 Chinese Type 033 medium-size submarines [1], which are the largest submarines operated by the KPAN to date. After over 40 years since their introduction into the KPAN, these submarines are unlikely to still be capable of searching and destroying enemy vessels in a high-threat environment. In previous naval exercises, the Type 033 submarines were seen firing torpedoes at fixed targets while being surfaced (Figure 1). Except for theatrical effects, such practices have little practical value.
Converting these obsolete submarines into nuclear weapon launch platforms could represent a relatively fast and economical way to establish a sea-based nuclear deterrence [3]. In his speech given at the launch ceremony, Kim Jong Un described the conversion as a “low-cost, hi-tech” approach that ensures “maximum efficiency in the light of the defense and economic strategy.” [4]
This shortcut also has drawbacks. The No. 841 submarine is likely longer than the original design (see Appendix); coupled with a new, large missile bay, the displacement of the submarine has increased. Commenting on the launch of the No. 841 submarine, an ROK Joint Chiefs of Staff official stated that “the submarine is not in a shape that can be operated normally.” [5] However, it is likely that the KPAN would adopt a more tolerant acceptance level. As a nuclear weapon launch platform, the No. 841 may be certified operational as long as it can perform basic manoeuvres and launch missiles in waters relatively well-guarded by other KPA assets. [6]
Future Nuclearization Plans
The launch of the No. 841 submarine is the first step in a series of developments pledged by Kim Jong Un. In his speech given at the launch ceremony of the No. 841 submarine, Kim emphasized three major steps for the future: [7]
- To rapidly convert all Type 033 submarines into “tactical nuclear attack submarines” with the No. 841 being the “standard type”;
- To increase efforts in building nuclear-powered submarines; and
- To build various kinds of modern warships needed for coastal defence, maritime patrol duty and offensive operations that are powered by modern naval engines.
As Kim Jong Un has stated previously that the KPAN should become “a component of the state nuclear deterrence carrying out the strategic duty”, [8] there is little doubt that follow-on submarines are also intended to be nuclear-capable. Judging by a corvette inspected by Kim Jong Un in August 2023, [9] some of the future KPAN surface combatants could also be nuclear-capable.
Conversion of Type 033 Submarines
Normally, a new submarine is expected to undertake harbour and sea acceptance tests before it is delivered to the user. Such tests could take many months, if not longer. [10] Though the No. 841 submarine likely inherited a wide range of subsystems from the original Type 033 hull, it may still undergo such acceptance tests due to the major modifications made and the increase in tonnage (see Appendix). Thus, conversion of the remaining Type 033 submarines may not be executed until the No. 841 successfully completes all key tests, including missile testfires. However, considering the urgency expressed during Kim Jong Un’s speech to convert all existing Type 033 submarines “at one go in the true sense of the word”,[11] the testing phase of the No. 841 is likely to be put on a fast track.
During his speech, Kim Jong Un called for the KPAN to “usher into a new era” in the “next five or ten years.” [12] This remark might reflect Kim’s expectation for the timeline of the conversion project. If the DPRK converts two submarines each year, the entire Type 033 fleet (consisting of about 20 hulls) could become nuclear weapon launch platforms in the next ten years. Assuming that each converted submarine accommodates between one and ten nuclear-armed missiles, a full fleet conversion could involve an arsenal of 20-200 nuclear weapons.
However, it remains unclear if a few Type 033 hulls would be kept back as donors for the “tactical nuclear attack submarine” fleet. A conversion of all existing hulls would indicate that the DPRK is able to manufacture or procure replacement parts for all subsystems of the Type 033 submarine.
Nuclear-Powered Submarines
The DPRK is not known to operate any pressurised water reactors, a type of nuclear reactor that is widely used for naval propulsion systems. The timeline for accomplishing this task is unclear. [13]
Modern Warships
The modern naval engines for surface combatants referred to by Kim Jong Un most likely involve gas turbine engines, [14] which are sophisticated machines required to work reliably for a long duration. [15] The timeline for accomplishing this also remains unknown.
On 21 August 2023, the Korean Central News Agency (KCNA) reported Kim Jong Un’s inspection of a corvette named “Patrol Ship No. 661.” During the inspection, the corvette reportedly launched at least one “strategic cruise missile,” which is presumed to be nuclear-capable. [16] Thus, it is plausible that some new warships to be built in the future will also serve as nuclear weapon launch platforms.
Further Implications
The nuclearization of the KPAN and the deployment of nuclear-capable missiles to KPA Ground Force units indicate that the KPA continues to advance its nuclear war-fighting posture by introducing nuclear weapons to previously conventionally-armed military branches. This development is also in line with (1) the DPRK’s long-time effort to increase the number of nuclear weapons and diversify their means of delivery and (2) the development trajectory of a KPA that is increasingly centred around nuclear weapons.
Arming the KPA Ground Force and the KPAN with nuclear weapons raises the possibility that the DPRK could eventually pursue a nuclear triad. Light bombers of the KPA Air and Anti-Air Force could in theory have the capacity to carry and launch land-attack cruise missiles or even light-weight aero-ballistic missiles. [17] However, there is no evidence the DPRK is currently pursuing this capability.
Appendix: Overview of the No. 841 Submarine Conversion Project
The existence of a relatively large [18] ballistic missile submarine has been known to external observers since July 2019, when DPRK leader Kim Jong Un inspected a Type 033 submarine that was apparently undergoing conversion into a ballistic missile submarine at the Pongdae Submarine Factory. Since then, this submarine has not been seen until its launch ceremony on 6 September 2023, [19] when it reappeared as the No. 841 submarine with several new features, including:
- Rounded bow (Figure 2);
- Diving planes moved from the bow to the sail (Figure 3); and
- Modification of the sail and missile bay (Figure 3).
These new features were likely introduced to follow Kim’s instructions. In a speech given at the launch ceremony, Kim Jong Un mentioned that during his July 2019 trip he “gave the task of introducing advanced power systems in the existing medium-sized submarine and improving their overall underwater operation capabilities.” [25] Technological hurdles might also be one of the factors contributing to the longer-than-expected interval between the submarine’s July 2019 debut and its launch in September 2023. [26]
The possibility that the No. 841 submarine and the submarine inspected by Kim Jong Un in July 2019 are two different submarines can not be entirely ruled out at this point. [27] Though considering Kim Jong Un’s command to rapidly convert all existing Type 033 submarines into “tactical nuclear attack submarines” (with No. 841 [28] being the “standard type”) and the lack of evidence pointing to a second submarine under another conversion project, this possibility remains unlikely.
Using KCTV footage (Figure 4) and the Google Earth measurement tool, the No. 841 has a measured length of approximately 80 m, which is roughly 3 m longer than the Type 033 submarine. [29] As of 19 September 2023, the No. 841 submarine is no longer visible at the pier. It is possible that the submarine has been moved to another location at the shipyard, such as under the roof of a nearby boat basin.
[1] An Ye, “中国江南造船厂援外军事项目回顾” [Reviewing military assistance of the Jiangnan Shipyard], Naval & Merchant Ships, 2006, available at: http://mil.news.sina.com.cn/p/2006-01-23/0725346203.html; “2021 Defense of Japan”, Japanese Ministry of Defense, available at: https://www.mod.go.jp/en/publ/w_paper/index.html
[2] 적해상목표에 대한 군종타격훈련을 조직지도하시였다 [Kim Jong Un guides naval strike drill], Rodong Sinmun, 31 January 2015, available at: https://dprkmedia.com/wp-content/themes/KPMSite/pdf.php?media=rodong&pdf-year=2015&pdf-month=1&pdf-day=31&attached=
[3] As foreseen by an independent observer. See: Twitter post by user Taepodong, 22 May 2017, available at: https://x.com/stoa1984/status/866496301667569664
[4] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[5] 합참, 北 전술핵공격잠수함에 "정상운용 가능한 모습 아냐" [JCS: “North Korean tactical nuclear attack submarine not in shape for normal operations”], Yonhap News Agency, 8 September 2023, available at: https://www.yna.co.kr/view/AKR20230908063300504
[6] For a discussion on how the KPAN might deploy their sea-based strategic assets, see: Tianran Xu, “Constraints and Outlook: Future Deployment of DPRK Ballistic Missile Submarines”, Open Nuclear Network, 5 January 2022, available at: https://opennuclear.org/publication/constraints-and-outlook-future-deployment-dprk-ballistic-missile-submarines
[7] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[8] “Respected Comrade Kim Jong Un Makes Congratulatory Speech in Celebration of Navy Day”, KCNA, 29 August 2023,available at: http://www.kcna.kp/en/article/q/624e32649d11c459e48c132588392616.kcmsf
[9] Tianran Xu, Jaewoo Shin, Elin Bergner, “Nuclear Risk Assessment Report - August 2023”, Open Nuclear Network, 12 September 2023, available at: https://opennuclear.org/publication/nuclear-risk-assessment-report-august-2023
[10] For example, see: “Submarine prototype could be ready ahead of schedule”, Taipei Times, 2 April 2023, available at: https://www.taipeitimes.com/News/front/archives/2023/04/02/2003797167. “Navantia Completes Initial Sea Trials Of Isaac Peral (S-81) Submarine”, Naval News, 27 May 2022, available at: https://www.navalnews.com/naval-news/2022/06/navantia-completes-initial-sea-trials-of-isaac-peral-s-81-submarine/. “French Navy Receives its Second Next-Generation Nuclear-Powered Submarine”, The Maritime Executive, 18 August 2023, available at: https://maritime-executive.com/article/french-navy-receives-its-second-next-generation-nuclear-powered-submarine
[11] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[12] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[13] “Today’s launching ceremony will be as burdensome to our opponents as is our building a new-type nuclear-powered submarine.” See: “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[14] Judging by a naval engine factory tour made by Kim Jong Un in early September 2023. See: “Respected Comrade Kim Jong Un Inspects Pukjung Machine Complex and Major Munitions Factory”, KCNA, 3 September 2023, available at: http://www.kcna.kp/en/article/q/88f82710e24720b2d4349e9b34c18bdc.kcmsf
[15] It is worth noting that turbo engines used to power military aircraft are also gas turbine engines. In fact, these aircraft engines are often converted into naval gas turbine engines. Thus, a successful naval gas turbine engine project might encourage Kim Jong Un to embark on a more ambitious plan to develop or reverse engineer modern aircraft engines, on the basis of which combat aircraft modernization could be pursued in the long term.
[16] Tianran Xu, Jaewoo Shin, Elin Bergner, “Nuclear Risk Assessment Report - August 2023”, Open Nuclear Network, 12 September 2023, available at: https://opennuclear.org/publication/nuclear-risk-assessment-report-august-2023
[17] The DPRK has developed a small aero-ballistic missile referred to as the Hwasong-11Ra. Assuming that the Hwasong-11Ra has a weight comparable to that of its ROK counterpart, the KTSSM (1.5 tons), it may be possible for the Harbin H-5/Il-28 of the KPAF to carry at least one Hwasong-11Ra after necessary modifications (the Harbin H-5/Il-28 has a maximum payload capacity of 3 tons). See: Tianran Xu, “Brief on 27 July 2023 Parade of the DPRK”, Open Nuclear Network, 8 August 2023, available at: https://opennuclear.org/publication/brief-27-july-2023-parade-dprk; “South Korea to start series production of new KTSSM short range tactical ballistic missile”, Asia Pacific Defense Journal, 30 November 2020, available at: https://www.asiapacificdefensejournal.com/2020/11/south-korea-to-start-series-production.html; “国产轰-5最大载弹量3000公斤曾成功实施核试验” [Home-made H-5 bomber, with a maximum payload capacity of three tons, successfully conducted nuclear tests before], PLA Daily, 4 January 2010, available at: http://mil.news.sina.com.cn/2010-01-04/0718579471.html?from=wap
[18] In comparison to an experimental ballistic missile submarine operated by the DPRK. See: Tianran Xu, “Ballistic Missile Submarines and Submarine-launched Ballistic Missiles of the Democratic People's Republic of Korea”, Open Nuclear Network, 16 April 2021, available at: https://opennuclear.org/publication/ballistic-missile-submarines-and-submarine-launched-ballistic-missiles-democratic
[19] In a report by Kim Jong Un during the Eighth Congress of the Workers Party of Korea (WPK), Kim mentioned that “a medium-sized submarine had been remodelled experimentally to enhance the ‘existing subsurface operational capabilities’ of the Korean People’s Army (KPA) Navy.” The submarine being mentioned was likely the submarine inspected by Kim during his July 2019 inspection. See: “Great Programme for Struggle Leading Korean-style Socialist Construction to Fresh Victory. On Report Made by Supreme Leader Kim Jong Un at Eighth Congress of WPK”, KCNA, 9 January 2021, available at: http://www.kcna.kp/en/article/q/4bd89fa5293bdf0a82d3f4323d1636e2.kcmsf
[20] “Supreme Leader Kim Jong Un Inspects Newly Built Submarine”, KCNA, 23 July 2019, available at: http://www.kcna.kp/en/article/q/29765936ffadd2657650846784357a1b.kcmsf
[21] “Ceremony of Launching Newly-built Submarine Held with Splendor in Presence of Respected Comrade Kim Jong Un”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/54c10cba542ecad949930e434de8baab.kcmsf
[22] 旅顺口 游旅顺潜艇博物馆 [Touring the Lvshun Submarine Museum], ce.cn, 24 August 2018, available at: http://m.ce.cn/bwzg/201808/24/t20180824_30110783.shtml
[23] “혁명활동소식]경애하는 최고령도자 김정은동지께서 새로 건조한 잠수함을 돌아보시였다” [Supreme Leader Kim Jong Un Inspects Newly Built Submarine], KCNA, July 2019, available at: https://www.youtube.com/watch?v=ZkFig69qytM&ab_channel=PaektuTV%EB%B0%B1%EB%91%90%EC%97%90%EC%84%9C%ED%95%9C%EB%9D%BC
[24] “Ceremony of Launching Newly-built Submarine Held with Splendor in Presence of Respected Comrade Kim Jong Un”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/54c10cba542ecad949930e434de8baab.kcmsf
[25] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[26] For example, see: Vann H. Van Diepen. “Hey, Boomer: What Happened to North Korea’s Ballistic Missile Subs?” Vann H. Van Diepen, 38 North, 10 July 2023, available at: https://www.38north.org/2023/07/hey-boomer-what-happened-to-north-koreas-ballistic-missile-subs/
[27] Independent defence analyst H I Sutton raised the possibility that at least two Type 033 submarines underwent conversions, with one into a strategic type and the other into a tactical type. See: “Further Analysis Of North Korea's New Missile Submarines”, Covert Shores, 17 September 2023, available at: http://www.hisutton.com/North-Korea-Submarines-Compared.html
[28] “Respected Comrade Kim Jong Un Makes Congratulatory Speech at Ceremony for Launching Newly-Built Submarine”, KCNA, 8 September 2023, available at: http://www.kcna.kp/en/article/q/a244151196662609d466a37d1f9ce288.kcmsf
[29] Both Beyond Parallel and 38 North measured the submarine with high-resolution satellite images. Their initial measurements vary by approximately 9 m. Beyond Parallel estimated that “there have been minimal, if any, changes to the overall length of the submarine” although “although it is too early to provide a definitive analysis.” 38 North estimated the length to be “around 86 meters, including 9.3 meters of the bow under the hall entrance.” A standard Type 033 submarine is 76.6 m long. See: Joseph S. Bermudez Jr., Victor Cha, Jennifer Jun, “North Korea Launches New Ballistic Missile Submarine”, Beyond Parallel, 11 September 2023, available at: https://beyondparallel.csis.org/north-korea-launches-new-ballistic-missile-submarine/; Peter Makowsky, Jack Liu, “Sinpho South Shipyard: New Submarine Makes Debut, but With Many Questions To Be Answered”, 38 North, 8 September 2023, available at: https://www.38north.org/2023/09/sinpho-south-shipyard-new-submarine-makes-debut-but-with-many-questions-to-be-answered/; “常规潜艇033型” [Type 033 conventional submarine], Dalian Lvshun Submarine Force Museum, available at: http://www.qtmuseum.com/about/cgqt033xd86.html
[30] Established with a high resolution satellite image released by Beyond Parallel. See: Joseph S. Bermudez Jr., Victor Cha, Jennifer Jun, “North Korea Launches New Ballistic Missile Submarine”, Beyond Parallel, 11 September 2023, available at: https://beyondparallel.csis.org/north-korea-launches-new-ballistic-missile-submarine/
[31] “金正恩同志をお迎えし、新たに建造した潜水艦の進水式が盛大に開催” [Kim Jong Un attends launch ceremony of new type submarine], KCTV, 8 August 2023, available at: https://www.youtube.com/watch?v=4mjmPNqdfVQ&ab_channel=dprknow