Hwasong-15 Transporter erector vehicle
Hwasong 16 at the 75th WPK anniversary parade 2020.
The Hwasong-15 (KN-22) was launched for the first time on November 29, 2017, when this liquid-fueled ICBM flew on a lofted trajectory to an altitude of 4,500 km. If flown on a standard trajectory, it could have a feasible reach of 13,000 km, which, according to David Wright of the Union of Concerned Scientists, “is significantly longer than North Korea’s previous long-range tests.” According to North Korea’s Korean Central News Agency (KCNA), this flight test was of “an intercontinental ballistic rocket tipped with super-large heavy warhead” which could reach “the whole mainland of the U. S.”
The new ICBM, presumably a Hwasong-16, appears to be approximately 25-26 m long and 2.5-2.9 m in diameter—about 4-4.5 m longer and about 0.5 m larger in diameter than the North’s Hwasong-15 ICBM flight tested once in November 2017. Indeed, the new missile has been correctly characterized as the world’s largest mobile ICBM—in part because countries with ICBMs generally seek to make their road-mobile ICBMs smaller so they can be more mobile and concealable.
That said, we estimate the new missile’s launch weight at roughly 100,000-150,000 kg, compared to some 80,000 kg for the Chinese DF-41 solid-propellant, road-mobile ICBM and about 104,000 kg for the former Soviet SS-24 rail-mobile solid ICBM.
The first stage of the new ICBM appears large enough in diameter to accommodate four of the Soviet RD-250-sized rocket engines believed to power the Hwasong-15 (which uses two in its first stage). The number and type of engine used in its presumed second stage are unclear, making the new missile’s throw-weight capability uncertain. Based on the assumption of four RD-250-type engines in the first stage, however, we estimate the new missile could, in principle, deliver 2,000-3,500 kg of payload to any point in the continental United States—much greater than the Hwasong-15’s assessed 1,000 kg payload capability to the same range.
But why would the North Korean’s need or want such a big missile? Especially since the Hwasong-15 would appear to have sufficient range/payload capability and room for improvement to meet North Korea’s operational targeting needs, and is much easier to move and conceal. There are two main possibilities, which are not mutually exclusive.
First, there may be a political rationale for producing or parading the new system. An unexpected “super heavy” ICBM would be a classically Khrushchevian statement of North Korea’s technical prowess, the robustness of its ability to threaten the US, and the permanence of its nuclear weapons status. It is worth noting that there has been no open-source evidence that the new ICBM’s apparent first-stage propulsion system has been ground-tested, and one analyst has noted that “no North Korean ICBM design that was *first seen at a parade* has seen flight-testing to date.”
Second, there may be operational reasons to make such a large missile. The North may want to be able (or to be seen as able) to deliver a much larger payload to anywhere in the US.
In terms of larger payloads, the North may be working toward developing multiple independently-targetable reentry vehicles (MIRVs). Perhaps the North’s current nuclear RVs are larger and heavier than we expect, and so the Hwasong-15 cannot carry enough such RVs along with the size of post-boost vehicle (PBV) the North currently can provide to dispense them. Or perhaps the Hwasong-15 can be MIRVed but the North wants to be able to deliver more MIRVs per booster.
It should be noted that North Korea has not demonstrated a militarily useful MIRV capability, which is technically demanding. For example, it has yet to flight test a PBV, much less the deployment of MIRVs from a PBV. Given the technical demands of MIRVs, it might instead first deploy non-independently targetable Multiple Reentry Vehicles (MRVs) like the US, USSR, and UK did. Even in this case, the North might want more payload capability to deploy more or larger MRVs.
Another reason for having a bigger payload capacity is the desire to carry more and/or more RV-like (heavier) decoys to spoof US missile defenses than is possible with the Hwasong-15. Alternatively, the North may have decided that it wanted to possess or portray the capability to deliver a “super heavy” single large thermonuclear RV against US cities for political or deterrent effect. While this also is Khrushchevian in nature, one should recall that the Soviet SS-18, Chinese CSS-4 and US Titan-II ICBMs were deployed with massive single RVs having up to nine megatons of yield.
Another size-related question raised by the new ICBM is: why make it road-mobile? Here, too, there could be a political component; after all, it is the world’s biggest mobile ICBM. But to the extent the North truly intends to deploy this system, it would almost certainly judge that road-mobile basing would be more survivable than silo- or other fixed-basing, even though the sheer size and weight of the new ICBM would render it less mobile than the Hwasong-15 and more constrained in the portions of the road network it could use, (limited to smooth, paved roadways), and probably needing to fuel the missile after it was erected at a launch site (adding to vulnerability and reducing response time).