In late 2023, Russia began utilizing North Korean ballistic missiles in its struggle in opposition to Ukraine. Considered one of them is the Hwasong-11A, also referred to as Hwasong-11Ga (“Ga” is the primary letter of the Korean alphabet) or because the US designator KN-23. This missile resembles the Russian Iskander short-range ballistic missile (SRBM), additionally in use in opposition to Ukraine. Reportedly, the North Korean missiles are getting tougher to intercept and extra correct. Evaluation based mostly on photos, video evaluation, and laptop simulations of the North Korean missile’s reported trajectories exhibits that the Hwasong-11A is bigger and heavier than the Iskander and confirms longstanding assessments that, just like the Iskander, it may well fly maneuvers that may problem missile defenses.
Non-Ballistic Trajectories
Determine 1 exhibits that, at first look, the Hwasong-11A and the Russian Iskander are very comparable. They’re launched vertically, after explosives blow off straps that connect them to short-launch rails. Each have moveable vanes mounted of their exhaust nozzle that deflect the thrust to steer them within the route of their targets. Each missiles even have moveable aerodynamic tailfins.
After engine burnout, a conventional ballistic missile flies a ballistic trajectory, decided by gravity (and by aerodynamic drag whereas contained in the environment). Consequently, if an air-defense system can monitor it, it may well predict the place to ship an interceptor missile. In precept, that interceptor solely has to regulate its trajectory to compensate for measurement errors.
Some ballistic missiles can fly extra sophisticated trajectories. They could initially fly a so-called depressed ballistic trajectory, with the apogee (the best level of the trajectory) at a a lot decrease altitude than a standard trajectory. This implies they’ll keep beneath the horizon of an air protection radar for longer. Moreover, within the denser environment at decrease altitudes, they’ll use aerodynamic management fins to generate raise and to maneuverability, complicating the power to foretell the place they are going to go.
Such maneuvers can embrace pitching down sharply to method the goal from instantly above. In principle, a maneuverable missile also can fly a gliding flight, just like the hypersonic missile North Korea examined in 2022. Alternatively, it may well fly range-extension maneuvers during which it climbs up utilizing aerodynamic raise when at low altitude, earlier than dropping down once more as a result of decrease atmospheric density at increased altitudes. Such a trajectory is named a skipping trajectory. Close to the bottom factors and through its ultimate descent, the missile may maneuver sideways. This makes its trajectory much more unpredictable.
Vary-extension maneuvers prolong the missile’s path via the environment by producing aerodynamic raise at the price of rising drag. That drag causes the missile to lose velocity, which probably makes it simpler to intercept within the ultimate part of its flight. On the finish of its September 2021 take a look at flight, for instance, the KN-23 would have been barely supersonic.
Initially, Ukrainian Patriot missile protection techniques had appreciable success intercepting Iskanders, in addition to Kinzhals, that are an air-launched model. Lately, interception charges have gone down, nonetheless, this can be the results of these missiles flying tougher maneuvers. Each Russian missile varieties have lengthy been anticipated to have the ability to fly non-ballistic trajectories.
Previous to the Hwasong-11A getting used in opposition to Ukraine, there have been clear indications of it flying non-ballistic trajectories too. Desk 1 offers an outline of Hwasong-11A take a look at flights carried out by North Korea, based mostly on experiences by the UN Panel of Specialists on the DPRK. Regardless of the flights reaching all kinds of ranges, their apogees are sometimes comparable. The 2 launches in July 2019 are a transparent instance: each missiles reached an apogee of fifty km, however one travelled 430 km whereas the opposite travelled 690 km. If these trajectories would have been ballistic, their apogees could be completely different.
One of many screens in {a photograph} of Kim Jong Un (Determine 2), ostensibly exhibits a part of one of many missile’s trajectories, suggesting a skipping trajectory. Moreover, for some flights, the UN additionally experiences the missile flying “pull-up manoeuvres” or “irregular trajectories.”
Hwasong-11A Properties
In accordance with a 2019 evaluation revealed by the UN, the Hwasong-11A has a diameter of 0.92 m and a size of seven.4 m, similar to the Iskander, and a spread of 450 km with a 400 kg warhead, and an total mass of three,800 kg. With Hwasong-11A missiles getting used in opposition to Ukraine, extra data has grow to be accessible. Preliminary reporting confirmed similarities with the Iskander but in addition talked about that the Hwasong-11A is much less correct. Investigations of wreckage of missiles that got here down in Ukraine revealed that the missile has an inertial measurement unit, for navigating, which is up to date utilizing satellite tv for pc navigation. Wreckage additionally reveals it has a diameter of 1.1 m (roughly 20 p.c bigger than the Iskander) and a heavier warhead (maybe weighing as a lot as 1000 kg). Based mostly on Ukrainian assessments, it has a most vary “set at as much as 650 km.”
Figuring out the missile’s diameter permits measuring its size. In September 2021, two KN-23s had been launched from a rail boxcar. By scaling a picture of one among them with this diameter, we discover a size of 8.77 m (with solely a small error margin), see Determine 3. The 1.1 meter diameter and a heavier payload had been additionally assessed in a 2023 evaluation of missile photos from North Korean media by the Fondation pour la Recherche Stratégique (FRS). The FRS evaluation, nonetheless, posits a missile that, whereas nonetheless longer than the Iskander, is shorter and has much less take-off mass and propellant mass than the present evaluation. The missile may very well be shorter than it seems from Determine 3 if the DPRK had been to have manipulated the {photograph}’s proportions to obscure the missile’s true form and dimension. Nevertheless, previous to the launch in Determine 3, doorways opened within the boxcar’s roof to permit the missiles to be erected, with these doorways subsequently hanging down the boxcar’s sides. Their dimension (measured vertically) matches the width of the openings within the roof (almost horizontal). This exhibits that North Korea has not manipulated the proportions.
Different photos affirm the length-over-diameter ratio: it is a significantly bigger missile than the Iskander. Just like the Iskander, it’s fairly stubby, although. This has two benefits: it makes the construction extra inflexible (serving to it to face up to the stress of maneuvers) and limits the missile’s pitch second of inertia, which probably makes it extra maneuverable.
The KN-23’s efficiency could be assessed based mostly on the accessible data on the missile’s dimension, the properties of different comparable missiles and their propellants, and measuring the take-off acceleration in a video of the launch. This enables estimating missile parameters wanted for laptop simulations of the missile’s flight, such because the mass and propellant burn time. The related parameters are listed in Desk 2.
A measurement of the KN-23’s form, based mostly on pictures, permits estimating its aerodynamic properties. These are wanted to simulate the missile’s maneuvers. The simulation program calculates a ballistic trajectory in the direction of a specific distance, by iteratively altering how the missile pitches over throughout its burn time. For a range-extension maneuver, the simulated missile flies such that its lift-over-drag ratio is maximized. This system iteratively finds how lengthy the missile wants to do that to get near the goal.
Within the ultimate a part of the flight, the mannequin assumes that the missile steers in the direction of the goal utilizing proportional navigation (a generally used steerage algorithm). If this mannequin is dependable, the simulations ought to have the ability to recreate the reported take a look at flights.
Flight Simulation Outcomes
The flight simulation was in a position to efficiently recreate the previously-reported take a look at flights, displaying within the course of that the KN-23 has demonstrated numerous completely different trajectory varieties (and thus ranges). Determine 4 exhibits the trajectories. These outcomes affirm that the mannequin can characterize the missile’s efficiency.
Depressed trajectory. In a simulation of one of many July 2019 flights, a depressed ballistic trajectory to a spread of 430 km ends in a 50 km apogee, as reported by the UN.
Depressed plus one range-extension. A simulation of the second July 2019 flight reveals a trajectory during which the missile first flies the identical depressed trajectory as the primary July 2019 flight, adopted by a single range-extension maneuver that permits it to cowl 690 km.
Determine 5: North Korean visualization of part of the July 2019 trajectory in an enhanced and straightened picture (a) and a visualization of the simulated trajectory (b) with the yellow trajectory reaching 430 km and the crimson 690 km. (Pictures: Open Nuclear Community and Savelsberg.)
A visualization of the trajectory ensuing from the simulation intently matches the ostensive (partial) trajectory proven on Kim Jong Un’s display screen in July 2019, see Determine 5.
Ballistic trajectory plus two vary extensions. The missiles launched from the railway boxcar in September 2021 reached a 60 km apogee and a spread of 800 km. Based mostly on simulations, this corresponds to a ballistic trajectory to a spread of about 475 km, adopted by two range-extension maneuvers.
Ballistic trajectory plus pitch-down. Two missiles launched in January 2022 reached an apogee of solely 20 km, overlaying a spread of 190 km. Simulated ballistic trajectories to 210 km lead to a 20 km apogee, however the missiles can hit their targets at 190 km by pitching down sharply.
Clearly, by flying a ballistic trajectory with two consecutive range-extension maneuvers the missiles can fly farther than the 650 km “most” vary reported in Ukrainian media. This “most” could also be based mostly on a purely ballistic trajectory with none maneuvers; the simulation exhibits a most vary below these circumstances of 674 km with an apogee at 182 km. Alternatively, 650 km matches a depressed trajectory adopted by a single range-extension maneuver, which might supply a compromise between a low apogee, an unpredictable trajectory and the rate of the missile.
To date, the simulated trajectories concerned maneuvers within the vertical route solely. Nevertheless, the missile can probably use a few of its aerodynamic raise to show horizontally. The simulation program can discover how a lot of the entire raise is required to fly a flip in the direction of a specific goal. Determine 6 exhibits two difficult examples, each simulated with an preliminary depressed ballistic trajectory with a 60 km apogee.
Flying a single range-extension maneuver and utilizing a few of the raise to show permits the missile to achieve a goal that’s 580 km down-range and displaced by 175 km within the cross-range (horizontal) route (i.e. to the aspect of the ballistic trajectory). If the missile makes use of most of its raise to show, it may well even flip again (hitting a goal at cross-range distance of 100 km). Whereas such maneuvers trigger the missile to lose velocity, an interceptor could not have the ability to match them. Moreover, based mostly on the KN-23’s preliminary ballistic trajectory, an air-defense unit, reminiscent of a Patriot unit, could anticipate the missile to land outdoors of its defended space and due to this fact not try an interception, to protect scarce and costly interceptors. Nevertheless, by maneuvering, the KN-23 could fly into the defended space and pose a menace in spite of everything, however too late for the air protection unit to react.
Conclusion
Data from Ukraine and pictures of the missile present that the Hwasong-11A, whereas externally just like the Russian Iskander, is significantly bigger and heavier, with a bigger warhead. Its design permits it to fly maneuvers which can be very difficult to air defenses. That is unhealthy for Ukraine but in addition doesn’t bode nicely for South Korean and US air defenses in a doable battle in Korea.
A part of this work was offered on the NDIA Missile Protection Convention, in Tokyo in October 2025. This text doesn’t mirror any official place or coverage of the Authorities of the Netherlands.
