Some unresolved questions surround the huge new mobile missiles that North Korea showed off in last month’s parade. Most of all: what will they carry, and when will the North Koreans reveal it through flight-testing?
Let’s start with what we can observe. The external characteristics of the weapon are consistent with a two-stage, liquid-propelled ICBM. In many ways, it’s similar to the Hwasong-15, which North Korea tested in 2017, but on a larger scale. My CNS colleagues estimate that the new missile is about 25 m long, compared to the roughly 20 m-long HS-15. It has a first stage of about 2.4 m in diameter, compared to the approximately 2.1 m diameter of the HS-15.
Like the HS-15, the Monster Missile features a “skirt” at the base of its first stage, suggesting a cluster of gimbaled engines, and an evocatively named “shroud” over its payload section at the front. That’s a hollow cover that pops off after the missile leaves the atmosphere, allowing whatever the missile carries to deploy.
As Mike Elleman and Vann van Diepen were quick to observe, the HS-15 already appears capable of sending a heavy payload to anyplace on the mainland of these United States. It follows that the new missile wasn’t built for greater range, but to carry a bigger, heavier payload. Which means… what?
Even before the parade, veteran intelligence analysts Markus Garlauskas and Bruce Perry noted that the logical next step for the North Korean ICBM program would be to deploy multi-warhead missiles in order to thwart U.S. missile defenses. Ensuring that North Korea’s nuclear weapons can penetrate the American “shield” may be what Kim Jong Un meant when he said in 2017 that “our final goal is to establish the equilibrium of real force [or “effective balance of power”] with the U.S. and make the U.S. rulers dare not talk about [a] military option for the DPRK.”
The U.S. pioneered the multiple reentry vehicle (MRV) concept in the early 1960s, followed by the multiple independently targetable reentry vehicle (MIRV). The Soviet Union caught up with their own versions within a decade or so. You could think of MRV as nuclear grapeshot, spraying a handful of bombs across one area. MIRV is more precise and more adaptable; it involves a small rocket engine called a post-boost vehicle, or “bus,” that pushes each warhead it carries onto a selected course, sending them to different targets if desired.
Some combination of multiple warheads and missile-defense countermeasures–chaff, decoys, and so forth–has become the favorite in this morbid little guessing game. If they’re ambitious, perhaps the North Koreans might be trying to replicate Britain’s Chevaline payload, which was designed to let its Polaris missiles thwart nuclear-tipped interceptors placed around Moscow. Chevaline was a two-warhead system with a post-boost vehicle that dispensed countermeasures into various patterns in space. It’s also rather well-documented today, as these things go.
There’s another possibility that I’ve yet to see explored at length, though. Let’s call it a dark horse. It’s another approach to beating missile defense, and one that requires a heavy payload, but no more than a single warhead per missile. That’s the fractional orbital bombardment system (FOBS).
FOBS was a Soviet innovation, brought to fruition in the mid-1960s, before the USSR developed its own multiple-warhead missiles. It involved a modified ICBM that launched its payload into low earth orbit. When the payload approached its target, an onboard retro-rocket would fire, deorbiting the warhead.
The advantage of FOBS was its ability to circumvent NORAD’s lines of early-warning radars in Canada. The FOBS weapon could be launched in any direction, allowing the USSR to launch an attack over the South Pole if desired.
Today’s early-warning radars don’t just provide warning; they also supply crucial data to the Ground-based Midcourse Defense (GMD). These radars are located in Alaska, Greenland, the UK, California, and Massachusetts, pointing north, west, and east, whereas the interceptors themselves are mostly in Alaska, waiting for an attack from the north. Thus, the same old FOBS concept remains applicable. It’s even enjoying new life in Russia, whose president has said that the Sarmat multi-warhead missile can attack over either the North or the South Pole.
With the ability to attack in FOBS mode, North Korea could compel the United States to an unhappy choice: either build what amounts to a substantially new, south-facing defensive architecture, or accept that it cannot physically prevent nuclear attack from Pyongyang, even under the sunniest of assumptions about GMD’s performance.
Even if North Korea is building a FOBS today, its leaders probably anticipate a transition to MIRV in time, following the Soviet precedent. But FOBS could have certain advantages for now. First, the technology simply might be more rapidly attainable. Second, sticking with just one warhead per missile demands less fissile material. Third, it also avoids creating pressure to return to nuclear testing to demonstrate the smaller, lighter warheads most suited to MRV or MIRV. Fourth, being able to deorbit a payload essentially anywhere means that North Korea could finally conduct a fully realistic and instrumented test of an intercontinental-class reentry vehicle on its own territory, or close to its own shores; they’d just have to fly one all the way around the world.
There’s an uncomfortably large chance that we’ll find out soon what the Monster Missile hides under that shroud. A transition to a Biden administration on January 20, 2021 gives Kim Jong Un an incentive to try to demonstrate the existence of an “effective balance of power” beforehand, since it might strengthen his hand without directly challenging the newly inaugurated president. Kim has set the 8th Workers’ Party Congress for January as well; the success of a “new strategic weapon”–either real success or merely alleged–could set the stage for changes in governing structures and the direction of policy.
Whatever does happen, I can’t see any benefits from sitting back and waiting for North Korea to demonstrate the ability to overcome GMD by whatever means. That will mean bargaining for the reaffirmation of Kim Jong Un’s April 2018 pledge not to test long-range missiles or nuclear devices, which he declared a dead letter in January of this year. How that will work will be up to the new team in Washington, but the sooner they decide on their approach, the better.
(For more on this subject, see the April 2019 CNS report, Options for a Verifiable Freeze on North Korea’s Missile Programs.)
