North Korean SLBM Surface Launch Fleet: An Open Source Investigation

When North Korea fired the Pukguksong-3 submarine-launched ballistic missile back in October, something funny appeared in one of the images released about the test. A fairly large ship was stationed directly in front of the missile’s smoke plume. As with any large, expensive piece of equipment, I wanted to find out more about the ship using information gleaned from public sources.

A brief eyeball measurement shows that the ship is perhaps a hair narrower than the missile is long. According to CSIS, the missile’s length (and therefore roughly the ship’s width) is between 7.8 and 8.3m. The vessel also has a white bridge, blue hull, and two masts – one near the bow and one just behind the bridge.

As luck would have it, a ship matching that exact description can be found on satellite imagery docked at the Toejo-dong naval base just south of the North Korean city of Sinpo.

The vessel seen in the missile test (let’s call it Ship A for simplicity’s sake) is normally moored at the corner of the long pier seen in the image above. However, it is occasionally moored within the secure boat basin north of the pier, near North Korea’s Sinpo-class submarine, a submersible ballistic missile test stand, and other support vessels (let’s call them Ship B and Ship C).

Building on the outstanding detective work done by Jeffrey Lewis and Dave Schmerler, who noticed that a North Korean SLBM was fired in 2015 from a towed barge, rather than a submarine, I wanted to see if the presence of support vessels in the secure boat basin indicates an increased likelihood of a missile test. After all, the support vessels could have towed the submersible test stand used to fire the missiles, rather than a submerged submarine firing the missiles.

Using a few different sources, I compiled what I think is a comprehensive list of all probable North Korean SLBM test dates since 2014.

I then recorded the appearances of Ship A, Ship B (the vessel Lewis and Schmerler noticed towing the launch barge in 2015), and Ship C (a smaller trawler) in the secure boat basin using Google Earth and the imagery in 38 North’s excellent analyses of the Sinpo shipyard. Finally, I recorded every time there was a missile test within two weeks before or after satellite imagery of the boat basin. (I did this in order to be able to compare the set of images taken around the same time as SLBM tests with the set of images that were not taken soon before or after missile launches.)

I found that appearances of the ships within the secure boat basin are highly correlated with missile test dates. The correlation is particularly strong with Ship A, the vessel seen in October’s test, and is also somewhat robust with Ship B, the vessel identified by Lewis and Schmerler.

Note that Y? or N? indicate likely or unlikely appearances of vessels in incomplete imagery or imagery affected by cloud cover.

Interestingly, the correlation with Ship C is weak. This absence of correlation could mean Ship C is used for other duties besides missile launches or that it was poorly suited for missile test duty and therefore only used once or twice. Also note that Ship C has a sister ship of the same size and appearance, which showed up in the imagery twice.

Finally, satellite images that do not show any of the three ships within the secure boat basin are highly correlated with a lack of recent missile tests. In fact, there is only a single image taken within two weeks of a missile test that did not show any of the three vessels in the secure boat basin.

That single image, taken on December 25, 2015, four days after an SLBM test, shows Ship A, B, and C moored together near the corner of the long pier where Ship A is typically stationed.

However, in KCTV footage of the missile test closest to this image, on December 21st 2015, a vessel, likely Ship B, is briefly visible near the missile launch site:

Ship B docked in the secure boat basin

Even though Ship A, B, and C were not seen in the secure boat basin following the December 21st missile test, the KCTV video shows that at least Ship B was an integral part of the test.

What do these data tell us? First, October’s test was not the first time Ship A or Ship B have been used to support North Korean SLBM launches. Unfortunately, Ship A does not appear in any other launch images released by the North Korean government besides the one from October’s test (although I would love to be proven wrong on that point). However, it may have been edited out of launch pictures, supported the launches off-scene, or towed the launch barge to the firing range before dropping it off and departing.

Second, Ship A is perfectly suited to towing the submersible missile test barge. Ship A appears to be a modified version of the deep sea fishing trawlers often seen around Sinpo. Like Ship A, the Sinpo fishing trawlers are around 38 meters long and 7 meters wide, often with one or two masts, and a white bridge. Here’s an example of one docked at the deep-sea fishing complex north of the Toejo-dong naval base:

These vessels are used to tow long nets for catching fish in deep, offshore waters. With few modifications, the same towing apparatuses could be used on Ship A to drag the submersible test barge out to sea. In fact, the white piece of equipment at the stern of Ship A, seen in several satellite images, could be used for precisely this purpose. Alternately, the vessel’s masts and booms could be used to operate towing equipment as well.

Based on the possible trawling gear and the extremely strong correlation between Ship A and Ship B’s appearances in the secure boat basin and missile tests, both ships are likely regularly used to tow the missile test stand.

Finally, the presence of ships in the secure boat basin does not make it certain that North Korea is preparing for a launch, but it does signal an increased likelihood of an SLBM test happening in the days or weeks after the imagery. During the pause in preparations for SLBM launches between August 2016 and summer 2019, none of the three support vessels were seen in the secure boat basin. Then, by mid-2019, as soon as another SLBM launch was on the table, the vessels began appearing in the secure boat basin once again.

Although open-source intelligence cannot tell us exactly how, when, and which ships participated in every SLBM test, information from publicly available sources can confirm that at least Ships A and B are critical parts of North Korea’s SLBM test launch surface fleet. Analysts should be aware of further satellite imagery or state media releases that help confirm or deny these vessels’ involvement in North Korea’s SLBM program.