North Korea’s Hwasong-15 ICBM and The Window of Vulnerability

In 1954 President Eisenhower exclaimed that, “soon even little countries will have a stockpile of these bombs, and then we will be in a mess.” Many have, correctly, emphasised that the Hwasong-15 ICBM is a big heavy missile. That’s half the picture. It’s a big missile developed by a small state. One of the more significant implications of the massive Hwasong-15 ICBM is that it represents a kind of “window of vulnerability” that has been long feared, small states with big bombs, but hitherto not seen. The label “window of vulnerability” in the context of North Korea is appropriate, I would argue, because North Korea is a small state with a relatively low population and low per capita GDP and the Hwasong-15 is a beast of an ICBM with throw weight and range sufficient to strike the entire continental United States with a heavy megaton to multi megaton thermonuclear warhead.

The Gulf War of 1991 I would consider to be the most important conflict of the post cold war era, on a number of grounds (I am planning a post about this), one of those being the way it inaugurated a growing concern that small regional powers would be able to develop nuclear weapons and the means to deliver them, that is missiles, such that the United States would be deterred from projecting massive military firepower in support of the system of world order.

How critical one was from 1991 onward regarding US military intervention had a lot to do with one’s understanding of what that system of world order is all about. Some have taken that to mean a type of liberal internationalism built around concepts of collective security, and those that did tended to have a favourable disposition toward US military intervention and various anti realist international relations theories. Yet others saw world order in terms of an increasingly globalised neoliberal order subsisting under an umbrella of power provided by US strategic hegemony, and those who took this view adopted a disfavourable disposition toward US military intervention. The picture is more complex than that, leaving out those who think Washington is too altruistic for its own good and the question of continuity, but it’s a good rough guide.

I submit that we are witnessing before our eyes the birth of something new in the nuclear age that has been with us since the Trinity test of July 1945. That something new is a small and economically vulnerable regional state possessing the capability to deter US intervention through a potential massive thermonuclear attack upon the US mainland.

One could argue that once China was what North Korea is today, and there is surely an element of truth to that but there’s also a sense in which that thesis is overdrawn. The United States was deterred from taking direct military action against China in the Korean War, for example, well before China denotated its first nuclear weapon, both because of China’s then close relationship with the Soviet Union and China’s large size and population. To be sure North Korean artillery arrayed along the DMZ within range of Seoul, chemical weapons and potentially biological weapons to boot, and the prospect of a bloody land war on the Korean peninsula have deterred US action much like with prenuclear China, but we’ve never spoken of North Korea in the same vein as China not even with the China of the 1950s and 1960s.

China is, and was, a great power. North Korea isn’t. That’s why the “loss” of China did and does rankle. Furthermore, continued advances in conventional military technologies, known as the revolution in military affairs, especially of stealth and precision strike, has always left open the prospect that North Korea’s artillery and chemical weapons if not vulnerable today could become so tomorrow. Surely Pyongyang views matters thus, a view no doubt partly driving its nuclear programme.

It is often argued that the recent acceleration in North Korea’s nuclear and missile programmes can be traced back to 2012. In December 2011 Kim Jong-il died leading to the accession of Kim Jong-un to the throne. From 2012 we have seen an upsurge in North Korea’s missile and nuclear programme, which has culminated in a multi hundred kilotonne hydrogen bomb test, and that of a compact deliverable device, and the Hwasong-15 heavy ICBM. The former, it is often and almost universally stated, accounts for the latter. That is the rise of Kim Jong-un explains the North Korean upsurge. As we know Kim Jong-un had adopted a policy of pursuing economic development parallel to a strategic buildup, which was different to the policy pursued by his father, and the 2012 acceleration was surely a reflection of that policy shift. Pointing to an external threat and presenting an image of steadfastness is something that also would have smoothed and cemented Kim Jong-un’s succession to the throne and ensured the continued stability of the monolithic totalitarian tyranny of the Korean Workers’ Party.

But the death of Kim Jong-il wasn’t the only thing that occurred in 2011, for in 2011 Barack Obama announced, “the pivot to Asia” which heralded a shift of military focus from the Middle East to the Asia-Pacific. Up until the late 1970s US military firepower was for the most part actively used in Asia, however from the latter part of the Carter administration, outside of NATOs central front, the main area of US military concern was the Middle East. The relative shift to Asia from 2011 onward, backed up with all sorts of rhetoric about deploying within region a capability to conduct stealthy and precise strikes deep into the Chinese hinterland but also the graduated expansion of US-South Korean military exercises, could plausibly be identified as a key factor in the acceleration of North Korea’s missile programme. It’s not just that the US was deterred from taking military action against North Korea because of its artillery and the prospect of a bloody land war. It’s also because North Korea wasn’t seen as important given Washington’s focus on the Middle East. It’s the high price low gain combination that explains much.

As noted Washington’s singular obsession with the Middle East, especially after the end of the Bush administration, ebbed for the first time in a long time. That combination of increasing conventional military capabilities and increasing strategic focus upon East Asia may well have exercised the minds of North Korean planners, hence accounting, in part, for the post 2011 acceleration. Planners in Pyongyang may well have judged that the pivot to Asia made North Korea that much more the potential subject of US military action given the growing strategic rivalry among the great powers in Northeast Asia. The ascendancy of conservative forces in South Korea would have magnified this effect.

Alas, after all that, I come to the window of vulnerability. There were two distinct, supposed, “windows of vulnerability” during the Cold War even though we mostly remember the second, which helped to bring Ronald Reagan to office. The first, in the 1960s, was occasioned by the R-36 (SS-9) ICBM the core stage of which was powered by three twin chambered RD-250 rocket engines (that’s the engine some suppose, I believe erroneously, powers the Hwasong-14 and Hwasong-15 ICBM booster). The R-36 had sufficient throw weigh to deliver a 10 megaton thermonuclear warhead (later 2-3 MIRVed warheads of lower yield) over 10,200km with a maximum, cross range or down range, error of 5km (so maximum CEP of 5.3km see below). That relative low accuracy but high yield combination, it was argued, made US Minuteman silos vulnerable to a first strike. Minuteman vulnerability made the US susceptible to coercion in a crisis, it was argued. That claim was, of course, fanciful, one reason being Washington had a secure second strike capability, but we forget that the first running of the window of vulnerability argument was used, in part, to justify the development of Multiple Independently Targetable Reentry Vehicles.

There’s some irony in this for the heavy ICBM successors to the R-36, especially the SS-18 ICBM, had larger throw weight and greater accuracy and that larger throw weight was used to MIRV these missiles with up to 10 warheads in the case of the SS-18. That made Minuteman III vulnerable to a first strike, it was subsequently argued, again upon essentially the same basis as the R-36, so necessitating, it was argued by Cold War hawks, the development of a heavy ICBM in response what became the MX missile. The MX, much like MIRV in the first instance, had more to do with target coverage rather than a putative window of vulnerability.

The Hwasong-15 features on the first stage a twin, March 18 revolution, engine cluster, and the second stage is quite larger than the Hwasong-14 second stage, so therefore carries more propellant, although we don’t know much about the second stage as of yet (the July 28 Hwasong-14 test reportedly employed four vernier engines for the second stage whereas the first Hwasong-14 test second stage reportedly employed two vernier engines) but the diameter suggests that it is much more powerful than the Hwasong-14 second stage as it can accommodate a more powerful engine array.

That equates to greater range, 13000+km, but also a greater throw weight than the Hwasong-14 meaning that large payload fairing is, to quote Mitsubishi, “not so squeezy.” Have a look at an image of the test RV reportedly in the payload fairing and the remaining volume. See computer screen to the bottom left, and note the sharp front end of the RV.


It has been speculated that the North Koreans could use that volume, in addition to BMD countermeasures such as decoys,to MIRV the Hwasong-15. That is true, but developing a MRV or Multiple Reentry Vehicle would, if history be any guide, proceed MIRVing and MIRVing is a complex technological enterprise. An early harbinger of MRV in the US context was the development, through the space programme, of a capability to launch multiple satellites from the one space booster onto the same orbit and an early harbinger of MIRV, again via the space programme, was acquiring the capability to launch multiple satellites to different orbits from the one booster. North Korea has launched single satellites, with a pretty mixed record, to low earth orbit from the Scud/Nodong derived Unha space launchers. North Korea’s missile programme is well ahead of its demonstrated space capabilities, but the big Hwasong-15 means a big space booster with greater payload capacity is on its way.

The Hwasong-15 missile and RV looks a lot like the Titan II ICBM. See my previous post for more detailed discussion. The Titan II had a 9 megaton thermonuclear warhead, the W53, based on the B53 bomb. The fissile primary of the W53 consisted of an all weapons grade uranium fissile core, rather than plutonium, and the mass of a significant quantity of a weapons grade uranium fissile core is larger than a plutonium fissile core meaning, all things being equal, that the weapons grade uranium bomb will have greater mass.

In philosophy the problem of the mind has been an especial puzzle, for obvious reasons. Overt behaviour we can readily perceive, as we can the hard or sloshy if you prefer matter of the brain, but the mind is not so readily accessible to empirical observation. That has been one of the main drawbacks of empiricist epistemology and physicalist ontology (and crude variants, not true to the originators, of logical positivism) now being addressed through the cognitive sciences, which are more grounded in rationalist thought.

That sounds like an odd digression, but I would argue it isn’t. We know a bit about the Hwasong-15 main engines because we can see them. We know something about North Korea’s propellants because the exhaust plume gives us clues about their nature. We know something about the airframe for what we see here too comes with empirical clues. We know something about the RV. But we know much less of the Hwasong-15’s mind, namely the missile’s guidance and control mechanism and so hence the missile’s accuracy. The gyroscopes and the accelerometers and their computational basis we cannot see, and they are the mind that lurks within.

David Wright, of the Union of Concerned Scientists, has argued that the accuracy of the Hwasong-12 IRBM, which has a range of 3,700km has a CEP accuracy of 5 to 10km quite possibly larger. Missile accuracy is largely a function of velocity and position errors prior to separation of the warhead from the last stage of the missile in space and the various buffeting forces upon reentry into the atmosphere. Both accumulate with range. That means should the Hwasong-15 use the same guidance technology as the Hwasong-12 it would be more inaccurate, making it especially inaccurate on Wright’s assumptions. It has been estimated, by John Schilling, that a North Korean ICBM using the Soviet R-27 SLBM guidance technology (the basis of the Musudan MRBM and the Pukguksong-1 and Pukguksong-2 medium range SLBMs) would have a down range error of 8km and a cross range error of 4km. Summing the cross range and down range errors and multiplying by 0.59 gives a CEP in this case of 7km. If based on Nodong guidance a cross range error of 10km and a downrange error of 20km is cited, giving a CEP of 18km.

However, everything that we can externally perceive suggests that North Korea’s missile programme has advanced handily. So why, then, adopt the assumption, by fiat, that what we can’t see, the mind, has not advanced handily also? It seems to me that this a priori assumption should not be uncritically accepted indeed, I’d go further, prima facie is not plausible. Consider one aspect of control technology we can see. North Korea has moved from jet vanes and tail fins (Scud/Nodong), to vernier engines (Musudan, Hwasong 12/Hwasong 14), and now with the Hwasong-15 to a two engine cluster that is most likely gimbaled. I submit that North Korea has more advanced gyroscopic and accelerometer technology than we have hitherto supposed, and one factor enabling this is the greater industrial precision afforded by computer numerically controlled machine tools. In the early days North Korea’s machine work led to buyers of North Korean missile technology, such as Iran, to express displeasure at the quality of the product.

Excluding the R7 this is the accuracy of early Soviet ICBMs up to the R-36 (1960s) that employed autonomous inertial guidance. These figures are from Bukharin et al Russian Strategic Nuclear Forces.

R-16
Range 11000-13000km
Maximum error 10km (down range or cross range not given taking 9km for the other gives max CEP 11km)
R-9a
Range 12500km
CEP 7km
R-36
Range 10200-15200
Maximum error 5km (down range or cross range not given taking 4km for the other gives max CEP 5.3km).

More accurate than what is often imputed to North Korea for ICBM distances. Having improved everything else regarding missile design parameters I find it difficult to believe that North Korea, for the Hwasong-15, would settle for whatever inaccuracies would accumulate from its legacy guidance and control technologies. I suspect that North Korea would aspire to design performance on a par with early Soviet and Chinese long range missiles as they have with other aspects of their programme, and that requires further improvement of guidance and control technology from legacy technology (not from here on, which is different).

I tend to think that the Hwasong-15 ICBM is designed to give North Korea the ability to strike the major cities of the United States with a heavy thermonuclear warhead, accompanied by anti BMD penetration aids, with accuracy and reliability sufficient to wipe those cities out. That is, to be blunt, to reliably kill millions to tens of millions of people. MRV and MIRV is for later, perhaps.

That equates to a type of window of vulnerability occasioned by a large throw weight ICBM only this time the window is real, the two of the Cold War were largely constructions justifying a strategic build up already committed to. I refer to it as a window of vulnerability as it shuts the door on US military escalation, much as the original two feared would, during a crisis only this time we are speaking of a window of vulnerability with respect to a small and impoverished regional state, and that’s new.

It has been suggested, including by the North Koreans themselves, that they may test a thermonuclear device by airbursting it over the Pacific or by testing a more powerful device, in the megaton class, underground. Either are a real possibility.

There’s more I’d like to say about what may happen from this point onward, but this post is already packing too much throw weight by way of words so I’ll leave it here, for now of course.

I’ll finish by returning where I started. When President Eisenhower uttered the exclamation with which I began the chairman of the Atomic Energy Commission, the odious Lewis Strauss, retorted that it would be “quite a long time before little countries” posed a nuclear threat.

Not anymore. That day has arrived.