It’s the Launcher, Not the Missile: Initial Evaluation of North Korea’s Rail-Mobile Missile Launches

North Korea’s September 15 launches of short-range ballistic missiles (SRBMs) from a railcar are significant for its first-time use of a rail launcher, not because of the missiles that were tested. The SRBMs launched are along the lines of existing types, and North Korea has long deployed hundreds of SRBMs. The use of a rail-mobile launcher is not significant for Pyongyang’s SRBMs, which are already road-mobile and highly survivable, but for the potential future use with intercontinental ballistic missiles (ICBMs). ICBMs are harder to make road-mobile than smaller missiles, and thus would benefit much more from rail mobility. While rail-mobility is less survivable than road-mobility, rail-mobile systems are significantly more survivable than fixed-base ones.

Information to Date

On September 15, South Korea’s Joint Chiefs of Staff announced that North Korea had fired two unidentified ballistic missiles from Yangdok, in its central inland region, just after 12:30 p.m. (03:30 GMT) that flew 800 km (497 miles) to a maximum altitude of 60 km (37 miles).[1] The missiles landed in the sea between North Korea and Japan. Japan’s Ministry of Defense originally issued a statement “saying that it ‘assumed’ the missile did not reach the country’s territorial waters or its exclusive economic zone (EEZ),” but later said the missiles landed inside the EEZ.

The next day, North Korea issued a statement confirming the launches, general launch location and the flight range.[2] It explained:

• This had been a “drill of the Railway Mobile Missile Regiment,” which had been organized by the Eighth Congress (January 2021) of the Korean Workers’ Party “to increase the capability for dealing intensive blow [sic] to the menacing forces in many places at the same time during necessary military operation and powerfully improve the ability to more actively cope with all sorts of threats as part of establishment of new defence strategy.”
• The purpose of the drill was “confirming the practicability of the railway mobile missile system deployed for the first time for action, evaluating without notice the combat preparedness of the new regiment and its ability to perform firepower mission and mastering the actual war procedures.”

The article also discussed “accumulating combat experiences of the missile regiment at the earliest possible time and expanding the regiment into [sic] brigade,” and concluded by stating: “it is of great significance in strengthening the war deterrent of the country that the railway mobile missile system has been introduced into reality.”

North Korean state media also released four still photographs depicting a KN-23-class short-range ballistic missile (SRBM) lifting off from a railcar just beyond the entrance to a rail tunnel in a wooded area.[3]

Later that day, it released a video of the launch that showed:

• Two railcars and a locomotive backing out of a rail tunnel.
• The hot launch of two missiles in turn from the end railcar, using two side-by-side erector/launcher mechanisms akin to the side-by-side arrangement used in the KN-23’s road-mobile launch vehicle. (The second railcar appeared to be used for cargo/support.)
• The launch railcar resembled a normal boxcar but had sliding-door-covered openings at all four corners used to vent the missile launch exhaust. The roof was divided longitudinally into two sections, each of which slid down over its side of the railcar to permit the missile on its side to be erected and launched. Two sets of leveling jacks at each end of the railcar had been put down to stabilize the railcar for launch.

Analysis and Implications

Based on the images, the missile appears to be the North’s KN-23 SRBM. The reported range and apogee, however, appear to be more consistent with the “new-type” of missile North Korea first revealed on March 25, 2021, that seems to be a KN-23 variant.[4] The 800-km range demonstrated in the latest launches is substantially greater than the 600-km range claimed by the North Koreans in March, much less the 450 km demonstrated by the original KN-23. The “new type” from March probably could reach 800 km if its payload were reduced, even if the North’s claim of a very large 2,500 kg payload almost certainly was overstated. The September 16 statement’s characterization of the latest launches as being for operational training purposes suggests North Korea considers the missiles already to have been proven, which would be inconsistent with an entirely new KN-23 version or variant.

The unveiling of a rail-mobile SRBM is surprising, given that North Korea has deployed all of its SRBMs on road-mobile launchers since their advent in the mid-1980s, and all of its new SRBMs (including the KN-23 and the “new type” variant) have been displayed on such launchers. Road-mobile deployment of such small missiles is straightforward and well-understood by Pyongyang.

The September 16 statement suggests that going rail-mobile was intended to diversify and add to the mobility and flexibility of the missile force and its ability to “deal a heavy blow at the threatening forces multiconcurrently [sic] with dispersive firing across the country.”[5] Pyongyang may also have seen propaganda value in revealing a hitherto unknown basing mode, and one cannot rule out the possibility of a new pet project of the reputedly train-loving Kim Jong Un.

A new basing mode would certainly diversify the force, although rail-mobility isn’t really needed for SRBMs to “deal a heavy blow.” Rail-mobile missiles are much more survivable than fixed-based ones, although relatively small SRBMs and medium-range ballistic missiles (MRBMs) are even more survivable when road-mobile, because they can move and deploy off-road and camouflaged. Rail-mobile missiles, however, cannot leave the fixed, well-known rail network.

Adding rail-mobile launchers would bolster the size of the SRBM force. The September 16 statement suggests the “Railway Mobile Missile Regiment” is operational or on the verge of being so. Based on Soviet practice, a mobile missile regiment would have nine (in this case, dual) launchers; a good guess would be deployment in three “battalion” trains with three launchers each. A missile brigade might have two to three such regiments, if analogous to North Korean artillery brigades. North Korea already possesses a large number of trucks able to transport SRBMs, however, and even many able to haul MRBMs. It is unclear whether modifying railcars to launch SRBMs would be cheaper than modifying trucks, given that missile erector-launchers need to be added in both cases and that addition comprises the bulk of the work needed on a road-mobile launcher (no sliding roof or exhaust vents required as for a rail launcher).

Where rail-mobility has more potential to make a military contribution is with much larger intercontinental ballistic missiles (ICBMs). North Korea has flight tested and/or paraded four types of liquid-propellant mobile ICBMs on large road-mobile launchers. But it has always been unclear how many road-mobile ICBM launchers North Korea possesses or is capable of producing or procuring. It would be able to modify many dozens of its 23,900 existing freight railcars to launch ICBMs, obviating any limits on road-mobile launcher production.[6]

The North’s current liquid-propelled ICBMs would be especially suitable for rail-mobile deployment. It would be easier to move such ICBMs by rail in an already fueled state, thus avoiding long set-up and fueling times prior to launch. Rail transport would subject the fueled missiles to a smoother ride and allow better environmental control than road mobility. Moreover, all of the needed support capabilities (including propellants and fueling infrastructure even if the missiles were transported unfueled) could simply be added in additional cars to the missile train. This is much easier to move and less conspicuous and vulnerable than the many trucks that would have to be added to an equivalent road-mobile deployment.

The new Hwasong-16 (KN-27) liquid ICBM—the world’s largest mobile ICBM, weighing some 100,000 to 150,000 kg fueled—would be a prime beneficiary of rail mobility. (It has yet to be flight tested, and its deployment prospects are unknown.) If road-mobile, it probably would be constrained to smooth, straight roads and being transported unfueled, thus adding to its vulnerability and response time. Rail deployment would significantly improve its mobility and survivability.

Solid-propellant missiles are the next logical step in North Korean ICBM development. Such missiles already incorporate all of the propellants, and thus are much heavier than unfueled liquid propellant systems. A first-generation small solid-propellant ICBM probably would weigh some 30,000-40,000 kg; it could be made road-mobile, but also would be well suited for rail deployment. The USSR/Russia deployed the heavier (104,500 kg), medium-sized SS-24 solid-propellant ICBM on railcars from 1989 to 2005, and India has deployed the lighter solid-propellant Agni-III intermediate-range ballistic missile (48,300 kg) on rail-mobile launchers since 2011.

As noted previously, North Korean rail-mobile missiles would be much more survivable than fixed-based systems. They could be dispersed along much of the North’s 7,435 km of railways, although 97 percent of that is single-tracked and much of it is in “truly bad shape,” which would limit how much of the network would be usable for missile trains (especially with hefty ICBMs). Missile trains could be configured to look like civilian freight trains, hidden in rail tunnels (which also would offer some protection against attack), dispersed to remote sidings and camouflaged. Decoy missile trains also could be deployed to confuse attackers.

At the same time, the North Korean rail network is already a prime target for attack in wartime, given its role in transporting and supplying North Korean conventional forces. A rail-mobile missile force could expect to be regularly harassed and attacked by allied forces enjoying air superiority, and to have its movement impeded by strikes on chokepoints, bridges, tunnels and rail yards—even without any special effort made to attack the missile force per se. The advent of rail-mobile missile deployment no doubt also would spark specific allied efforts to detect, track and strike missile units in addition to the general air campaign against the rail network. Thus, as already noted, rail-mobile missiles would not be as survivable as road-mobile systems, which can utilize the much larger road network (724 km of paved and 24,830 km of unpaved roads) and, in most cases, can go off-road, hiding under camouflage away from any conspicuous place like a rail line.

The Bottom Line

The significance of the September 15 SRBM tests is not the missiles, which are along the lines of existing types, but the use of a rail-mobile launcher, which has little added value for the North’s already road-mobile SRBM force but important implications for its ICBMs. ICBMs, which are harder to make road-mobile than smaller missiles, would benefit from rail mobility much more than smaller systems. While rail-mobility is inferior to road-mobility in terms of promoting survivability, rail-mobile systems are significantly more survivable than fixed-base ones.

1. [1]

   See: Hyonhee Shin and Josh Smith, “North and South Korea conduct missile tests as arms race heats up,” Reuters, September 15, 2021, https://www.reuters.com/business/aerospace-defense/nkorea-fired-unidentified-projectile-yonhap-citing-skorea-military-2021-09-15; and Choe Sang-Hun, “North Korea Fires 2 Ballistic Missiles as Rivalry With the South Mounts,” The New York Times, September 15, 2021, https://www.nytimes.com/2021/09/15/world/asia/north-korea-ballistic-missiles.html.

2. [2]

   “Secretary Pak Jong Chon guides launching drill of Railway Mobile Missile Regiment for inspection,” Voice of Korea, September 16, 2021.

3. [3]

   “Secretary Pak Jong Chon guides launching drill of Railway Mobile Missile Regiment for inspection,” Rodong Sinmun, September 16, 2021.

4. [4]

   Joseph Dempsey, “North Korea tests new SRBM,” International Institute for Strategic Studies, April 28, 2021, https://www.iiss.org/blogs/analysis/2021/04/mdi-north-korea-srbm.

5. [5]

   “Secretary Pak Jong Chon guides launching drill of Railway Mobile Missile Regiment for inspection,” Rodong Sinmun.

6. [6]

   “Major Statistics Indicators of North Korea 2019,” Statistics Korea, 2019.