North Korea’s Pukguksong-3 SLBM Test: What Insights Might We Draw?

We’ve surely heard by now North Korea tested a new sea launched ballistic missile, the Pukugksong-3 SLBM, on October 2. We’ve also surely heard the working level talks on denuclearisation between the US and North Korea collapsed not long thereafter. Let’s concentrate on the first, for now. A North Korean SLBM test (not necessarily of the Pukguksong-3) was anticipated. There was quite a bit of, very good, satellite image analysis going around in the period prior to it suggesting something was in the works. That was all right on the money.

One of the first things that came to mind when the launch location was roughly pinpointed, and then North Korean state media confirmed the missile tested was the Pukguksong-3, was Kim Jong-un’s August 2017 visit to the Chemical Materials Institute of the Academy of Defence Science. That was the first time we heard of the Pukguksong-3 (it featured on a poster visible in images released of the visit). I’ll return to this in short order.

Here’s a sample from the satellite image analysis of Jack Liu and Jenny Town at 38North not long before the Pukugksong-3 test (published September 26);

“Imagery from August 26 shows the presence of four vessels berthed at the secure boat basin… [snip]… In imagery from September 23, the cylindrical canister and associated support equipment now appear on the submersible test barge along with support vessels. The canister transport truck and crane are still on the quay. These activities suggest that preparations for a pop-up ejection test are likely underway.”

And there she was

Notice the cold launch

The test was certainly conducted from a submersible test barge, as the above linked article points out, and the Pukguksong-3 note was also cold launched

“This test is routinely done prior to actual missile launches, to ensure that the missile can be ejected at the proper speed and angle before committing to ejection and launch from the submarine.”

What might we say about the missile? What may we say about the submarine to which it might be deployed? What might we say about the test’s strategic implications?

The October 2 test flew on a lofted 910km trajectory and to a 450km range. As David Wright of the Union of Concerned Scientists quickly pointed out if flown on a standard trajectory the range would have been 1,900km. Initial reports had two missiles being launched, however we know now North Korea tested the single two stage SLBM. As the images above show the Pukguksong-3 is a solid fuel missile, North Korea’s longest range solid propellant missile. The dimensions are of interest, especially the diameter. Unfortunately, the pictures released do not give us a reference frame to conclusively calculate this. Michael Elleman, at 38North, argues from analogy the diameter is likely 1.4-to-1.5 metres

“the Pukguksong-3 is likely to be about 1.4 to 1.5 meters in diameter, and roughly 7.8 to 8.3 meters long, making it similar, if not the same as, the land-based Pukguksong-2, but with a substantially shortened and blunted nose cone. The shorter nose cone was likely adopted to fit the missile into a submarine-launch tube. The US Poseidon and Trident SLBMs and the Chinese JL-2 all employ similar front ends.”


“The Pukguksong-3’s size and configuration is consistent with other SLBM designs. The US Polaris SLBM had a diameter of 1.37 meters, early-French SLBMs were 1.5 meters in diameter and China’s JL-1 was 1.4 meters. The first stage motor of the Pukguksong-3 is roughly two times the size of the second stage motor. This ratio is similar to those found on the US, French and Chinese SLBMs. These similarities are driven by engineering optimization, and not by one country copying another’s design decisions.”

If there’s one thing North Korea’s recent round of missile tests have done, not that it was needed, is they’ve blown the “bluff hypothesis,” in addition to Pyongyang’s missile programme is dependent on foreign expertise, theses both out of the water.

This is where the 2017 Chemical Materials Institute of the Academy of Defence Science visit by KJU enters the picture. Elleman had a good 38North write up of this at the time. One of the things we saw then was KJU inspecting a solid motor casing made of composite fibres

“The large bronze-colored vessel examined by Kim Jong Un is an advanced, light-weight casing designed to house solid propellant. Its size, roughly 1.4-1.5 meters in diameter, is consistent with North Korea’s two existing solid-fuelled missiles: the submarine-based Pukguksong-1 and the land-based Pukguksong-2.”

The Pukguksong series has been developed from the Soviet 2,400km range R-27 Zyb (liquid propellant) SLBM which had a metal casing.  Furthermore, Elleman writes (of the Pukguksong-3 depicted in the poster),

“Building the Pukguksong-3 using lighter-weight composite motor casings, instead of cases made from metal, should allow the new missile to fly further, though exactly how much further is difficult to determine. If North Korea masters the production processes, maintains a reliable supply chain for the filaments and resins needed to create the cases, and adheres to strict quality control procedures, the Pukguksong-3 might be capable of reaching targets 2,000 km away.”

Which is bang on target with the 1,900km estimate for the Pukguksong-3 based on the October 2 test parameters.  The dimensions are interesting because of another thing KJU (partially) showed off, namely a filament winding machine which is used to wind together the composite material of the missile motor case.

“It is unclear if the machine can produce motor casings larger than a 1.5 meter diameter. If not, North Korea will need to acquire a larger winding machine to produce motor casings large enough to power intercontinental ballistic missiles (ICBMs).”

Should the Pukguksong-3 have a maximum diameter greater than 1.5m, then the filament winding machine KJU showed off can produce motor casings larger than 1.5m. The UN Panel of Experts in its latest report stated that, according to the assessment of a member state, North Korea is working on the first stage of a solid propellant ICBM. In which case, yes, North Korea does have a filament winding machine capable of producing missile motor casings greater than 1.5m in diameter.

What about the submarine to house the Pukguksong-3 SLBM? We know, thanks to this exceptionally good analysis from H.I. Sutton at his Covert Shores submarine warfare analysis website, that the submarine KJU recently showed off is an SSB modification to the Romeo class vintage Soviet era diesel submarine. Sutton suggests the sail has been lengthened and heightened to accommodate (at time of the writing) Pukguksong-1 SLBMs (KN-11 US designation) in the aft battery compartment. Most likely, Hutton concludes, this configuration could house two KN-11 SLBMs possibly a maximum of three. Should the Pukguksong-3 be for the SSB Mod Romeo submarine then a 1.4-to-1.5 metre diameter estimate for the missile is consistent with what we know.

There have been reports that North Korea is working on another submarine, the Sinpo-C, larger than the Romeo class Mod, although we have not seen it. A diameter larger than 1.5 metres for the Pukguksong-3 would be consistent with that. The 38North analysis of recent activities at the Sinpo South shipyard, linked above, does suggest submarine construction is underway although whether that’s of the SSB Mod Romeo or the rumoured Sinpo-C is unclear. You’d think the former. One of the questions looked at there is whether a new submarine is due for launch, the 38North report is sceptical of this however analysts at the Centre for Nonproliferation Studies at the Middlebury Institute for International Studies argue the satellite images suggest a launch sooner rather than later. I’d argue they’re right about that; too many dots fall neatly into place on this (KJUs submarine construction hall visit, the satellite images of activity at Sinpo South, the PG-3 test).

I suspect something like this. Reports have suggested that the Pukguksong-3 test represents North Korea pushing the envelope on missile technology. I agree, but I suggest we might consider going further. The Pukguksong-3 SLBM test does not push the envelope, instead it understates North Korea’s solid fuel production capabilities. Pyongyang has built itself a solid fuel missile with two composite case motors designed for the SSB Romeo class submarine, but the facilities at the Chemical Materials Institute can do better than that.

Don’t forget when KJU visited the Institute the Pukguksong-3 wasn’t the only missile on display (in poster form, of course). So was the Hwasong-13 (KN-08) ICBM. That we previously knew basically to be a mock up of a liquid propellant ICBM based on the engine technology of the R-27 Zyb. That’s so ancient history now.

Image originally provided by KCNA. This enhancement is due to Nathan Hunt available on his Twitter feed

Note the (possible) three stage configuration above. Solid propelled ICBMs and solid propelled SLBMs of ICBM range are typically designed with three stages whereas liquid propelled ICBMs are typically designed with two.

Reports and commentary of the strategic implications of the Pukguksong-3 divided into two strands. The first, it gives North Korea a first strike capability. North Korea can launch a sneaky, undetected, first strike perhaps even against the United States itself.  The second, North Korea is working on a sea based leg of its strategic rocket forces as it seeks an assured second strike capability. The first can be dismissed whatever one thinks about the survival capability of the SSB mod Romeo submarine in so far as we are talking about the United States. A first strike capability doesn’t necessarily mean striking first undetected it means launching a disarming first strike. What we’re talking about here does not give North Korea that capability vis a vis the US. South Korea and Japan, however, is another matter. Whether intended or not, the (possible) capability alone will be of concern to Seoul and Tokyo. South Korea has a programme to acquire nuclear powered submarines to hunt Pyongyang’s ballistic missile submarines, a combination that adds a new dimension to strategic dynamics on and around the Korean peninsula.

I’m not too flashy on the second. I think this is a bit of mirror imaging. I doubt North Korea wants to build a bunch of submarines so at least one is permanently on deterrence patrol. Mainly because I don’t think Pyongyang would like what that would mean for its ultra centralised system of command and control. I’m more in favour of a third position. I tend to think this capability, whose manifestation is more imminent than many suppose, is part of a nuclear strategy not unlike that of China. I surmise that Pyongyang is developing a sea based version of its, what the Chinese call, “shooting a firecracker outside the front door” operational strategy. Pukguksong-3 SLBMs will surge from port in a crisis and they’re to target the ballistic missile defence systems of the region in particular. In that sense the sea based leg of North Korea’s nuclear forces are for assured deterrence but not quite in the manner usually envisaged. Remember that the KN-11 was initially seen as providing for an all-azimuth attack against South Korea’s THAAD radar. Now South Korea is indeed investing in more radars to address gaps in THAADs coverage, but I suspect that North Korea’s strategy for the Pukguksong-3 is not unlike that previously reputed for the KN-11. The Pukguksong-3, in addition to some of the other capabilities we’ve seen North Korea test in recent times, will present the battle assessment and response system of regional BMD with a complex, multi-facetted, challenge. BMD faces more problems than just the physics of interception.  Recall how initial assessments on October 2 wrongly assumed two missiles were launched. That, I submit, was a good example of how cognitive biases influence information processing and that was during a benign period certainly relative to a full-blown crisis. Reports at the time of the Pukguksong-3 test continued to repeat the canard North Korea does not have an RV capable of striking the mainland United States. That’s wishful thinking. The big story here is that Northeast Asia, and the United States, does not have a BMD system capable of addressing the North Korean challenge.

Of course, this all does pose dilemmas for strategic stability during a crisis on the Korean peninsula. We’ve got ourselves plausible submarine based nuclear escalation scenarios and don’t be thinking that’s years off because North Korea wants to build a nuclear navy with permanent deterrence patrols either.

If there’s one thing we’ve learnt about the North Korean nuclear crisis it’s that our penchant for wishful thinking leads us astray, both analytically and, crucially, regarding policy.

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