Two Halls Enter – One Sub Leaves

by Joseph Dempsey and Dave Schmerler

In recent months there has been renewed speculation over signs of an impending submarine launch from North Korea’s Sinpo South shipyard. However, as analysts await the next satellite image to study, their focus may be slightly misplaced…

 Awaiting Sinpo C?

The much anticipated submarine, previously shown in July 2019, is assessed as the country’s second ballistic missile capable submarine which appears to be a conversion of an existing Romeo/Type-033 attack submarine. Their first, the purpose built Gorae (Sinpo-B), was launched in 2014 and features single launch tube for trials of the Pukguksong-1 SLBM.  Unlike the original Gorae, the new submarine is believed to have several launch tubes, leading to the initial assessment that it represented more of an operational deployable example.

However, in the intervening period, three successive SLBM designs have emerged;  Pukkuksong-3, tested November 2019 from a submerged stand, while Pukkuksong-4 & 5 were paraded in October 2020 and January 2021 respectively.  Their larger diameter suggests incompatibility with the existing Gorae launch platform without extensive – if indeed feasible modification.  As such, the new submarine will likely play a much more crucial role in the further development of a deployable SLBM than initially thought.

Location, Location, Location

While the location of the July 2019 visit was never officially disclosed, the Sinpo South shipyard, home to the country’s SLBM program and their primary East Coast submarine facility, was the logical location. Analysts previously presumed the new submarine was being built in the largest construction hall, identifiable by its turquoise colored roof, because it was refurbished after the launch of Gorae in 2014, and that after its refurbishment, large rings suspected to form part of the hull construction started to appear and disappear next to this hall.

The presumed hall containing the new submarine has an extended jetty with rails and connection points for a Floating Dry Dock (FDD).  With this extended jetty, added after the building was refurbished, it was assumed that the new submarine would be refloated using a FDD, which led to recent speculation that the North was preparing to launch the new vessel seen in July 2019.

 After a careful review of the state media images released in in July 2019, it has become apparent that the new submarine is actually being assembled in the second, non-refurbished hall, adjacent to the presumed hall.

The authors noticed a few interior features from the most recent submarine inspection that correlate more accurately to the second construction hall with the slipway.  These features can be seen in the building’s various window placements, and a comparative shot taken from the inside of the presumed hall that was taken during a 2013 visit to the site by Kim Jong Un. The authors are not the first to postulate this new interpretation, as in January of this year open source researcher Nathan Hunt challenged the previous assertion of the refurbished hall being the assembly location by noting that internal images did not match up with how the presumed hall should look from the ground. 

The images that helped to form this reassessment can be seen in the series of mid-level window rows (in regards to their placement on the middle of the back and side walls of the second construction hall), the total absence of evenly spaced out skylight slits seen in the presumed location’s roof, and the apparent signature of a rectangular skylight seen on the body of the new submarine, which is absent in the presumed hall.

For comparison, the image from the inside of the presumed hall more accurately reflects the double-rowed, higher placed windows which remained post-refurbishment on the smaller northwestern side of the structure.

An explanation for how the observed ring segments were transported to the second, non-refurbished hall, can be seen in the rail line connecting the two halls to a presumed fabrication workshop. 

False indicator

 With this new interpretation more succinctly placing the new submarine in the adjacent non-refurbished construction hall, image signatures showing FDD movement would not be connected to any launching activity as the second construction hall employs a slipway where the new submarine would be launched by simply rolling out into the water.

With this method likely taking less time to complete with less external indicators of preparation, it is quite possible the launch itself could be easily missed in commercially available satellite images. The first visible indicator will likely be the displacement of the original Gorae from its covered berth to make way for the new submarine.

It is, however, unclear if and when this submarine will be launched. Though shown in an apparent advanced state of completion in July 2019, it is unknown when the conversion commenced and not unfeasible that visible progression of their SLBM designs may have superseded the design and/or required further modification. Other major submarine projects may also be active with earlier original reports and rings outside pointing to a larger Sinpo-C design than the conversion we saw, as well as more recent declared plans for a nuclear-powered submarine.


The authors would like to point out that Nathan Hunt first postulated this interpretation in January 2021 and would like to thank him for reopening the analysis of the new submarine’s assumed location. – source:


Joseph Dempsey, Research Associate at The International Institute for Strategic Studies (IISS) , is the development lead for the Military Balance+ online database, and contributes to The Military Balance and conducts other research.