North Korea launched a KN-23 short-range ballistic missile (SRBM) from its submerged GORAE/SINPO-class experimental ballistic missile submarine on October 19. The launch and associated announcements have much greater political than military significance. The test almost certainly is a political message directed against South Korea, which launched a very similar SRBM from a submerged submarine in September. The new submarine-launched ballistic missile (SLBM) is of marginal military significance given the North’s much larger, more survivable, and equally capable land-based mobile missile force (potentially including KN-23s). Moreover, the new missile’s short range would require its submarine carrier to sail much closer to allied anti-submarine defenses than the North’s other SLBMs. Use of a submarine would allow launching KN-23s from different directions than land-based missiles, but would only add marginally to the many options Pyongyang has to evade missile defenses.
Information to Date
South Korea reported that North Korea launched a ballistic missile on October 19, possibly from a submarine. The missile was launched from waters east of Sinpho, reportedly to a range of about 590 km and an apogee of about 60 km. (Another South Korean source reported the range as 430-450 km.) Japan reported a range of as much as 600 km and an apogee of 50 km on an “irregular trajectory,” and that two missiles had been launched.
On October 20, North Korea released a brief statement announcing the successful test-launch of “a new type submarine-launched ballistic missile.” The launch was said to have occurred “from the same ‘8.24 Yongung’ ship from which the first submarine-launched strategic ballistic missile was successfully launched five years ago” [i.e., the GORAE/SINPO-class missile test submarine]. The missile was said to have incorporated “lots of advanced control guidance technologies including flank mobility and gliding skip mobility.”
Accompanying the statement were five still photographs showing the “cold” launch from underwater, using a launch assist device (LAD)/sabot, of what appears to be the previously tested KN-23 solid-propellant SRBM. The missile appears to be the same one displayed in the October 12 photos from Kim Jong Un’s attendance the previous day at the opening of “The Defence Development Exhibition Self-Defense 2021.” The KN-23-like missile was displayed next to the larger, Pukguksong-1 (previously tested) and Pukguksong-5 SLBMs in a similar black-and-white paint job (as was the missile in the October 20 launch photos). The October 20 photos also included a shot of the GORAE/SINPO-class sub, with a new number “824” painted on the sail, appearing to surface with the missile launch hatch atop the sail partially open.
The reported range and apogee of the October 19 SLBM test is consistent with previous flights from road-mobile launchers of the KN-23 SRBM. The land-based version is “hot” launched, rather than being “popped up” using a LAD and then ignited as in the case of the SLBM version. But “cold” launch is much safer for the submerged launch platform and is a technology the North has used successfully with all of its previous SLBMs. The reference in the North Korean statement to “flank mobility and gliding skip mobility” is also consistent with the depressed trajectories and maneuverability attributed to the KN-23. (Lower in altitude than a purely ballistic flight path, depressed trajectories reduce the missile’s visibility to missile defense radars and stay within the atmosphere to permit maneuverability over a longer portion of the missile’s flight.)
The North’s claim that the missile was launched from the GORAE/SINPO-class submarine appears to be borne out by post-launch commercial imagery of the Sinpho South Shipyard on October 20. It is unusual to conduct the first launch of a new type of missile from a submarine rather than the submersible test barge North Korea typically uses for such testing, but the DPRK may have felt that the KN-23 and the cold-launch technique had been sufficiently well-tested that it was safe to make the first launch from the sub.
Because the GORAE/SINPO submarine has only one launch tube, its apparent use would seem to confirm that only one missile was launched on October 19, rather than the two near-simultaneous launches reported by Japan. Tokyo may have confused a single “irregular” missile trajectory that bobbed more than once above and below the radar horizon as two missiles. In any case, the US government would be able to confirm the number of missiles launched using infrared satellite data.
As is often the case with North Korean missile activities, the political motivations behind the test and its announcement are at least as important as the military/operational ones. The political signaling may be even more important in the case of such a short-range SLBM.
The DPRK’s October 20 statement claimed the launch “will greatly contribute to putting the defence technology of the country on a high level,” and “to enhancing the underwater operational capability of our navy.” A follow-up statement issued the next day claimed the test “was part of the normal activities for carrying out the medium- and long-term plan for the development of defence science and it did not pose any threat or damage to the security of the neighboring countries and the region,” that it “does not aim at a specified state or forces but is for preventing the war itself and defending the sovereign rights,” and that “the U.S. and south Korea have been ruled out as our arch-enemies.”
In reality, however, the political messaging behind the unveiling of a 430-600-km range SLBM is aimed primarily at South Korea. Beyond the short range of the missile, it almost certainly cannot be a coincidence that, just a few weeks after South Korea’s September 7 announcement (to great fanfare) of its first flight-test of a 500-km range SRBM from a submerged submarine, the North revealed the existence of and then test-fired a submarine-launched SRBM. The North’s KN-23 even looks like the South’s Hyunmoo-2B SRBM/SLBM, both of which appear to be inspired by the Russian Iskander SRBM. We do not know when North Korea began work on the SLBM version of the KN-23, although it probably would have taken at least several months to a year or two to do the necessary technical work and to modify the launcher in the GORAE/SINPO submarine. But the North could have known since at least 2015 or 2016 that the South intended to install launch tubes for the Hyunmoo-2B into the KSS-III (Jangbogo-III) submarines it was building.
The North likely sees the unveiling and launch of the new SLBM as having further political purposes. As is the case with its other recent missile launches, Pyongyang probably sees such activities as bolstering deterrence, trumpeting its technological prowess (not just over South Korea), generating prestige and legitimacy, and underscoring the foresight and accomplishments of the regime.
More perplexing, perhaps, is why North Korea issued on September 20 a highly unusual and technical denunciation of South Korea for launching an SRBM that was “clearly not an SLBM” from a submarine, when we now know it was clearly on track to do the same thing. The North decried the “funny yet surprising news…that south Korea tries to rank itself among the world SLBM possessors” even though it had just launched “a typical ground-to-ground tactical ballistic missile”—not a “wholesome SLBM with perfect underwater operational maneuverability and with the capability to give influence enough to tilt the war in one’s favor in terms of power,” like the North’s earlier SLBMs.
The military significance of the new SLBM, however, clearly is marginal. Contrary to some Western commentary that “It poses a huge risk…that could be a game-changer for South Korea and Japan,” or poses “a far greater threat to the United States,” the North Koreans came closer to the truth on September 20 when characterizing the very similar South Korean short-range SLBM: “Such meaningless missile [sic] is just for ‘bragging’ and ‘self-comforting,’ as it has only hundreds km of flight range and it can load conventional warhead weighing 1-2 ton at most and it is launched from conventional submarine.”
(The North is assessed to be able to deploy the KN-23 with nuclear weapons, unlike South Korea, which does not possess them. Pyongyang’s October 20 statement did not describe the new missile’s payload type, however, and did not describe the system as “strategic,” which many commentators associate with a nuclear payload—unlike how that statement described the SLBM tested five years earlier.)
North Korea already possesses hundreds of road-mobile SRBMs (potentially including KN-23s) and medium-range ballistic missiles that can cover targets throughout South Korea and Japan. Even if a KN-23-equipped submarine could carry more SLBMs than one fitted out for the North’s larger SLBMs, and if it would be easier to retrofit or build multiple subs for KN-23s than for larger SLBMs, a North Korean SLBM force is highly unlikely ever to come close to the number of land-based missiles able to reach regional targets. More of these land-based missiles (and still more in the future) would be as “valuable for striking hardened, high-value targets” as sub-launched KN-23s, and as “good for evading missile defenses.”
Moreover, submarines carrying short-range KN-23s, assuming they are ever built and deployed, would have to get much closer to their targets to be within range than subs carrying the North’s previously tested 1,200-1,900 km range Pukguksong-1 and -3 SLBMs—much less its larger, as-yet-untested Pukguksong-4 and -5. KN-23 subs would thus be much more vulnerable to detection and destruction. North Korea’s land-based mobile missile force is almost certainly more survivable than a future SLBM force, particularly if carrying KN-23s.
As with other SLBMs, KN-23 subs would be able to strike targets in South Korea from different directions than land-based missiles. (To do so for targets in Japan would essentially require sailing out of the East Sea/Sea of Japan, which is unlikely to be wise or worthwhile.) This could complicate the task of missile defenses deployed in the South, but would provide only a marginal increase to the many other options North Korea has to combat such defenses—to include saturation attacks, early-release submunitions, penetration aids, maneuvering re-entry vehicles, and possible future long-range cruise missiles (like the one flight-tested September 11 and 12), hypersonic boost glide vehicles (like the one flight-tested on September 28), and multiple reentry vehicles.
“Academy of Defence Science Succeeds in Test-Launch of New Type SLBM,” Rodong Sinmun, October 20, 2021.
“Kim Jong Un Makes Commemorative Speech at Defence Development Exhibition,” Rodong Sinmun, October 12, 2021.
“Answer of Spokesperson for DPRK Foreign Ministry,” KCNA, October 21, 2021.
“Clumsy SLBM Launch of S. Korea,” KCNA, September 20, 2021.