In July 2019, North Korea revealed a conventionally powered ballistic missile submarine (SSB) in the late stages of construction and announced that it would be deployed in the near future. However, since then, there has been no evidence of the SSB’s launch, despite numerous occasions when that was expected. It is unclear what is holding up this process, although there are likely three key factors at play.
It remains to be seen when or if the new SSB ever sees the light of day. It is possible that the sub will be reconfigured once a suitably sized SLBM completes development or that it will be reconfigured for use in another role, such as supporting minisubs or special operational forces. Pyongyang may decide to dismantle the new SSB altogether in favor of building a larger sub. The SSB may just be left in the construction hall until a course of action is decided or even indefinitely.
Whatever happens with the new SSB, a several-boat SSB force that could truly serve as a consequential and credible “leg” of a nuclear dyad or triad does not seem to be in the cards anytime soon. Pyongyang’s land-based missiles, which are much more survivable and cost-effective than an SSB force, are highly likely to remain the mainstay of its nuclear and missile forces.
A Long Time Coming
In July 2019, North Korean media reported that Kim Jong Un had “inspected a newly built submarine” and that the sub’s “operational deployment is near at hand.” Associated photos showed the presence of what appeared to be a substantially externally complete SSB inside a covered construction hall at the Sinpho South Shipyard. The sub seemed to be based on North Korea’s ROMEO-class submarine, which uses old Soviet technology, and apparently had room for three missile launch tubes in the sail.
North Korea began work on the infrastructure to build a new type of submarine in June 2014, according to analysis of commercial imagery, and by September 2016, construction of the SSB appeared to be underway.
Since mid-2019, there have been several instances where experts and analysts have predicted the imminent rollout of the new SSB based on various shipyard activities, upcoming North Korean ceremonial days, or trends in the North’s missile activities. These include:
North Korea could have rolled the SSB out of the construction hall at any time since at least the summer of 2020, when the parts yard apparently used to stage components flowing into the construction hall has been empty, suggesting the end of major construction, or July 2021, when the South Korean press claimed the Republic of Korea (ROK) and US intelligence assessed construction of the SSB was complete. As of June 10, 2023, there was still no open source evidence the SSB has been launched, although it is and will remain the case that the sub could be rolled out at any time in the future.
What’s Taking So Long?
The long period of time since Pyongyang publically reported the SSB’s “operational deployment is near at hand” strongly suggests there are some compelling reasons why the sub has remained in the construction hall.[1] Based on analysis of the available information, one or more of the following three key factors probably explains why the new SSB has been a no-show for almost four years.
Missile subs are not a high priority. When the new SSB was revealed, the US media often claimed that Kim Jong Un was “determined to deploy it as soon as he can” and had a “full steam ahead program to perfect his submarines.” Such commentary was bolstered by assessments that North Korea was seeking to develop a “second leg of the nuclear triad,” even “undeniably” so.
Clearly, the SSB program has not actually proceeded in this fashion and has not taken any central role in North Korea’s nuclear force. Pyongyang thus does not appear to have put much priority on ballistic missile submarines, and so there seems to be little pressure to finalize the new sub. (This lack of priority also is reflected in the associated SLBM program, discussed below.) A contrary example of what the North can do when it decides to ramp up the priority of a program is the recent attempt to place a reconnaissance satellite into orbit: a new satellite and space-launch vehicle—the Chollima-1—were developed, and in just over a month a new launch pad was erected from scratch and used to conduct the first (albeit unsuccessful) launch on May 31, 2023.
There are good operational and cost-effective reasons for the SSB not being a priority for North Korea, although we do not know the extent to which those reasons have influenced its decisions. The North’s large, longstanding force of road-mobile, land-based ballistic missiles offers substantially more survivability than noisy ROMEO-based SSBs that would be at substantial risk of acoustic detection and operate under conditions of allied air and naval superiority. SSBs will not expand the target coverage of land-mobile missiles or add meaningfully to the number of warheads North Korea can deliver—which can be done more cost-effectively by adding more truck- or railcar-based land-mobile missile launchers than by adding more resource-intensive, slow-to-build SSBs that only carry three SLBMs each.
The SLBM program is in flux. When the SSB was first unveiled, it was widely assumed that the sub would carry the Pukguksong-3 SLBM (about 8 meters long and 1.6 meters in diameter), a missile revealed by the North in 2017 and flight tested for the first and only time in October 2019. Since then, the North has displayed—but has not yet flight tested—three progressively larger (and thus longer-ranged) SLBMs:
This lack of SLBM developmental flight testing also suggests lower priority for SSBs. In stark contrast, North Korea has flight tested six new types of land-based ballistic missiles since the only Pukguksong-3 SLBM test in October 2019: two short-range ballistic missiles (SRBMs), two “hypersonic” medium-range ballistic missiles, and two intercontinental ballistic missiles. It also tested two new types of land-attack cruise missiles (LACM).
Having the longest-ranged SLBMs possible makes the most military and operational sense for Pyongyang. This allows the associated missile sub to strike targets that are farther away while staying in waters closer to North Korea (and thus farther from allied anti-submarine assets, and closer to North Korean air and naval assets that can help protect the SSB). The delays in flight testing any of the new SLBMs (reinforced by the lack of any known ejection testing[2]) may well have contributed to the delay in rolling out the new SSB, which would need to have its sail section modified to accept progressively larger launch tubes for the series of new SLBMs.
Moreover, if the new large SLBM is now the missile of choice, it is possible that the new SSB is simply too small to accommodate that missile. This might mean that the SSB has become obsolete even before seeing the light of day.
Further confusing the picture, North Korea launched a KN-23 SRBM from its single-tube GORAE (or SINPO)-class ballistic missile test submarine in October 2021. The test sub apparently is still configured to launch that much smaller, shorter-range missile (about 7.5 meters long and 0.9 meters in diameter) and would need to be reconfigured if it was going to be used in the flight testing of one of the larger SLBMs for ultimate deployment on the new SSB. Moreover, the GORAE’s missile hatch appears to be only 1.8 meters in diameter, which is too small to accommodate the new large SLBM. In any case, a deployed sub-launched KN-23 makes very little military sense, given the North’s large existing force of more survivable land-based SRBMs.
The SSB itself has problems. It is possible that the North encountered problems in the construction of the new SSB (or its conversion from a preexisting ROMEO) that it has still not overcome, that any such problems were somehow insurmountable or not cost-effective to rectify, or that the North came to realize the SSB would not meet its operational needs.[3] An example of the latter reason could be that, as noted above, the sub may be too small to accommodate the new large SLBM.
All that can be said at this point is that there has been no evidence that the SSB has been moved from the construction hall, and given the lack of activity in the construction hall’s parts yard since the summer of 2020, it does not appear that the SSB has thus far been dismantled or subjected to major reconstruction, or that a replacement submarine is being built alongside it.
Future Prospects Uncertain
It remains to be seen when or if the new SSB will ever be launched. There are four main possibilities for its future, listed in descending order of likelihood:
Whatever happens with the new SSB, a several-boat SSB force that could truly serve as a consequential and credible “leg” of a nuclear dyad or triad does not appear to be in the cards anytime soon. Pyongyang’s land-based missiles, which are much more survivable and cost-effective than an SSB force, are highly likely to remain the mainstay of its nuclear and missile forces.
It should be noted, however, that true “operational deployment” probably would take a year or more after rollout due to the highly likely need for fitting-out, acceptance trials, commissioning, and shake-down cruises as with other North Korean submarines. See Joseph Bermudez and Victor Cha, “Sinpo South Shipyard: Construction of a New Ballistic Missile Submarine?,” Beyond Parallel, August 28, 2019, https://beyondparallel.csis.org/sinpo-south-shipyard-construction-of-a-new-ballistic-missile-submarine.
Before conducting flight tests, SLBM programs usually conduct “ejection tests” or “pop-up tests,” in which the system used to eject the missile from the submerged submarine prior to ignition is tested using a dummy missile and a land-based rig or submersible platform.
See Tianran Xu, “Constraints and Outlook: Future Deployment of DPRK Ballistic Missile Submarines,” Open Nuclear Network, January 5, 2022, https://opennuclear.org/publication/constraints-and-outlook-future-deployment-dprk-ballistic-missile-submarines; and Joseph S. Bermudez Jr., Victor Cha, and Jennifer Jun, “Sinpo South Shipyard Update: Vessel Movements and New Construction,” Beyond Parallel, September 15, 2022, https://beyondparallel.csis.org/sinpo-south-shipyard-update-vessel-movements-and-new-construction.
See Vann H. Van Diepen, “Initial Analysis of North Korea’s “New Type Long-Range Cruise Missile,” 38 North, September 15, 2021, https://www.38north.org/2021/09/initial-analysis-of-north-koreas-new-type-long-range-cruise-missile; and Vann H. Van Diepen, “North Korea Launches Four “Hwasal-2” LACMs to Show Strong Deterrence and Rapid Response,” 38 North, March 1, 2023, https://www.38north.org/2023/03/north-korea-launches-four-hwasal-2-lacms-to-show-strong-deterrence-and-rapid-response.