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In late 2023, Russia started using North Korean ballistic missiles in its war against Ukraine. One of them is the Hwasong-11A, also known as Hwasong-11Ga (“Ga” is the first letter of the Korean alphabet) or as the US designator KN-23. This missile resembles the Russian Iskander short-range ballistic missile (SRBM), also in use against Ukraine. Reportedly, the North Korean missiles are getting harder to intercept and more accurate. Analysis based on images, video analysis, and computer simulations of the North Korean missile’s reported trajectories shows that the Hwasong-11A is larger and heavier than the Iskander and confirms longstanding assessments that, like the Iskander, it can fly maneuvers that can challenge missile defenses.
Figure 1. Launch of a North Korean Hwasong-11A in May 2019 (left) and a launch of a Russian Iskander ballistic missile (right). (Images: Korean Central News Agency; Russian Ministry of Defense)
Non-Ballistic Trajectories
Figure 1 shows that, at first glance, the Hwasong-11A and the Russian Iskander are very similar. They are launched vertically, after explosives blow off straps that attach them to short-launch rails. Both have moveable vanes mounted in their exhaust nozzle that deflect the thrust to steer them in the direction of their targets. Both missiles also have moveable aerodynamic tailfins.
After engine burnout, a traditional ballistic missile flies a ballistic trajectory, determined by gravity (and by aerodynamic drag while inside the atmosphere). Consequently, if an air-defense system can track it, it can predict where to send an interceptor missile. In principle, that interceptor only has to adjust its trajectory to compensate for measurement errors.
Some ballistic missiles can fly more complicated trajectories. They may initially fly a so-called depressed ballistic trajectory, with the apogee (the highest point of the trajectory) at a much lower altitude than a conventional trajectory. This means they can stay below the horizon of an air defense radar for longer. Furthermore, in the denser atmosphere at lower altitudes, they can use aerodynamic control fins to generate lift and to maneuverability, complicating the ability to predict where they will go.
Such maneuvers can include pitching down sharply to approach the target from directly above. In theory, a maneuverable missile can also fly a gliding flight, like the hypersonic missile North Korea tested in 2022. Alternatively, it can fly range-extension maneuvers in which it climbs up using aerodynamic lift when at low altitude, before dropping down again due to the lower atmospheric density at higher altitudes. Such a trajectory is known as a skipping trajectory. Near the lowest points and during its final descent, the missile may also maneuver sideways. This makes its trajectory even more unpredictable.
Range-extension maneuvers extend the missile’s path through the atmosphere by generating aerodynamic lift at the cost of increasing drag. That drag causes the missile to lose velocity, which potentially makes it easier to intercept in the final phase of its flight. At the end of its September 2021 test flight, for example, the KN-23 would have been barely supersonic.
Initially, Ukrainian Patriot missile defense systems had considerable success intercepting Iskanders, as well as Kinzhals, which are an air-launched version. Recently, interception rates have gone down, however, this may be the result of these missiles flying more challenging maneuvers. Both Russian missile types have long been expected to be able to fly non-ballistic trajectories.
Prior to the Hwasong-11A being used against Ukraine, there were clear indications of it flying non-ballistic trajectories too. Table 1 gives an overview of Hwasong-11A test flights conducted by North Korea, based on reports by the UN Panel of Experts on the DPRK. Despite the flights achieving a wide variety of ranges, their apogees are often similar. The two launches in July 2019 are a clear example: both missiles reached an apogee of 50 km, but one travelled 430 km while the other travelled 690 km. If these trajectories would have been ballistic, their apogees would be different.
Figure 2. Official North Korean photograph of Kim Jong Un, purportedly during a July 2019 Hwasong-11A flight test. The screen on the very right shows the claimed trajectory. (Image: Korean Central News Agency)
One of the screens in a photograph of Kim Jong Un (Figure 2), ostensibly shows part of one of the missile’s trajectories, suggesting a skipping trajectory. Furthermore, for some flights, the UN also reports the missile flying “pull-up manoeuvres” or “irregular trajectories.”
Hwasong-11A Properties
According to a 2019 assessment published by the UN, the Hwasong-11A has a diameter of 0.92 m and a length of 7.4 m, identical to the Iskander, and a range of 450 km with a 400 kg warhead, and an overall mass of 3,800 kg. With Hwasong-11A missiles being used against Ukraine, more information has become available. Initial reporting confirmed similarities with the Iskander but also mentioned that the Hwasong-11A is less accurate. Investigations of wreckage of missiles that came down in Ukraine revealed that the missile has an inertial measurement unit, for navigating, which is updated using satellite navigation. Wreckage also reveals it has a diameter of 1.1 m (roughly 20 percent larger than the Iskander) and a heavier warhead (perhaps weighing as much as 1000 kg). Based on Ukrainian assessments, it has a maximum range “set at up to 650 km.”
Figure 3. Hwasong-11A launched from a rail car in September 2021, with the missile length and diameter indicated. (Image: Korean Central News Agency, modified annotated by author)
Knowing the missile’s diameter allows measuring its length. In September 2021, two KN-23s were launched from a rail boxcar. By scaling an image of one of them with this diameter, we find a length of 8.77 m (with only a small error margin), see Figure 3. The 1.1 meter diameter and a heavier payload were also assessed in a 2023 analysis of missile images from North Korean media by the Fondation pour la Recherche Stratégique (FRS). The FRS analysis, however, posits a missile that, while still longer than the Iskander, is shorter and has less take-off mass and propellant mass than the current analysis. The missile could be shorter than it appears from Figure 3 if the DPRK were to have manipulated the photograph’s proportions to obscure the missile’s true shape and size. However, prior to the launch in Figure 3, doors opened in the boxcar’s roof to allow the missiles to be erected, with these doors subsequently hanging down the boxcar’s sides. Their size (measured vertically) matches the width of the openings in the roof (nearly horizontal). This shows that North Korea has not manipulated the proportions.
Other images confirm the length-over-diameter ratio: this is a considerably larger missile than the Iskander. Like the Iskander, it is quite stubby, though. This has two advantages: it makes the structure more rigid (helping it to withstand the stress of maneuvers) and limits the missile’s pitch moment of inertia, which potentially makes it more maneuverable.
The KN-23’s performance can be assessed based on the available information on the missile’s size, the properties of other similar missiles and their propellants, and measuring the take-off acceleration in a video of the launch. This allows estimating missile parameters needed for computer simulations of the missile’s flight, such as the mass and propellant burn time. The relevant parameters are listed in Table 2.
A measurement of the KN-23’s shape, based on photographs, allows estimating its aerodynamic properties. These are needed to simulate the missile’s maneuvers. The simulation program calculates a ballistic trajectory towards a selected distance, by iteratively changing how the missile pitches over during its burn time. For a range-extension maneuver, the simulated missile flies such that its lift-over-drag ratio is maximized. The program iteratively finds how long the missile needs to do this to get close to the target.
In the final part of the flight, the model assumes that the missile steers towards the target using proportional navigation (a commonly used guidance algorithm). If this model is reliable, the simulations should be able to recreate the reported test flights.
Flight Simulation Results
The flight simulation was able to successfully recreate the previously-reported test flights, showing in the process that the KN-23 has demonstrated a number of different trajectory types (and thus ranges). Figure 4 shows the trajectories. These results confirm that the model can represent the missile’s performance.
Figure 4. Simulated trajectories, for July 2019, September 2021, and January 2022. Solid curves represent ballistic trajectories, while the dashed curves represent the maneuvers. (Chart by author)
Figure 5. North Korean visualization of a part of the July 2019 trajectory in an enhanced and straightened image (a) and a visualization of the simulated trajectory (b) with the yellow trajectory reaching 430 km and the red 690 km. (Images: Open Nuclear Network and Savelsberg.)
Depressed trajectory. In a simulation of one of the July 2019 flights, a depressed ballistic trajectory to a range of 430 km results 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 in which the missile first flies the same depressed trajectory as the first July 2019 flight, followed by a single range-extension maneuver that allows it to cover 690 km.
Figure 5: North Korean visualization of a part of the July 2019 trajectory in an enhanced and straightened image (a) and a visualization of the simulated trajectory (b) with the yellow trajectory reaching 430 km and the red 690 km. (Images: Open Nuclear Network and Savelsberg.)
A visualization of the trajectory resulting from the simulation closely matches the ostensive (partial) trajectory shown on Kim Jong Un’s screen in July 2019, see Figure 5.
Ballistic trajectory plus two range extensions. The missiles launched from the railway boxcar in September 2021 reached a 60 km apogee and a range of 800 km. Based on simulations, this corresponds to a ballistic trajectory to a range of about 475 km, followed by two range-extension maneuvers.
Ballistic trajectory plus pitch-down. Two missiles launched in January 2022 reached an apogee of only 20 km, covering a range of 190 km. Simulated ballistic trajectories to 210 km result in a 20 km apogee, but 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 “maximum” range reported in Ukrainian media. This “maximum” may be based on a purely ballistic trajectory without any maneuvers; the simulation shows a maximum range under these circumstances of 674 km with an apogee at 182 km. Alternatively, 650 km matches a depressed trajectory followed by a single range-extension maneuver, which would offer a compromise between a low apogee, an unpredictable trajectory and the velocity of the missile.
So far, the simulated trajectories involved maneuvers in the vertical direction only. However, the missile can potentially use some of its aerodynamic lift to turn horizontally. The simulation program can find how much of the total lift is needed to fly a turn towards a particular target. Figure 6 shows two challenging examples, both simulated with an initial depressed ballistic trajectory with a 60 km apogee.
Figure 6. Extreme trajectories, with the missile using some of its lift to turn, reaching a 175 km cross-range distance (red trajectory) and using most of its lift in the turn, to turn back and hit a target at a 100 km cross-range distance (blue trajectory). The dashed lines represent the ground paths. (Chart by author)
Flying a single range-extension maneuver and using some of the lift to turn allows the missile to reach a target that is 580 km down-range and displaced by 175 km in the cross-range (horizontal) direction (i.e. to the side of the ballistic trajectory). If the missile uses most of its lift to turn, it can even turn back (hitting a target at cross-range distance of 100 km). While such maneuvers cause the missile to lose velocity, an interceptor may not be able to match them. Furthermore, based on the KN-23’s initial ballistic trajectory, an air-defense unit, such as a Patriot unit, may expect the missile to land outside of its defended area and therefore not attempt an interception, to preserve scarce and expensive interceptors. However, by maneuvering, the KN-23 may fly into the defended area and pose a threat after all, but too late for the air defense unit to react.
Conclusion
Information from Ukraine and images of the missile show that the Hwasong-11A, while externally similar to the Russian Iskander, is considerably larger and heavier, with a larger warhead. Its design allows it to fly maneuvers that are very challenging to air defenses. This is bad for Ukraine but also does not bode well for South Korean and US air defenses in a possible conflict in Korea.
Part of this work was presented at the NDIA Missile Defense Conference, in Tokyo in October 2025. This article does not reflect any official position or policy of the Government of the Netherlands.
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첫댓글 기동을 하면 요격을 피할 수 있지만 기동하며 에너지를 써서 사거리는 좀 짧아지고, 결국 trade-off입니다.
우러전쟁 관심도가 많이 낮아져서 이스칸데르나 KN-23의 요격성공률이나 명중도에 관한 기사들이 이전처럼 많이 나오질 않네요..
잠수함 싣느라 짜리몽땅 한 줄 알았는데, 기동에 대한 장점도 있었군요. 또 새로 배우고 갑니다.
저렇게 옆으로도 많이 빗겨 날아가면 방공포병은 이걸 어디서 어떻게 요격을 해야 할 지 의사결정도 쉽지 않고, 결국은 통합지휘망에 연결돼야 할 것 같습니다.