| Introduction

North Korea announced that it test-fired two types of strategic cruise missiles from the submarine "Hero Kim Kun Ok" on October 14, 2026.¹⁾ It also stated that the purpose of the launch was to inspect the mobilization posture of its underwater combat system, to master the strategic mission capabilities of its navy, and to demonstrate the reliability and capability of its war deterrent. In particular, the photographs released show the two missiles launched through a vertical launch system (VLS) and a horizontal torpedo tube respectively, which makes the test notable in that North Korea actually demonstrated a capability to launch strategic cruise missiles from a submarine.

Since 2024, North Korea has focused on verifying the range, flight performance, and warhead yield of its strategic cruise missiles, and since 2025 it has broadened its development goals toward securing the operational capability of launch units and the operational reliability of the weapon system. In 2025 in particular, it verified long-range flight performance using ground-based launch platforms and rehearsed operational mission procedures, and in 2026 it launched strategic cruise missiles from a destroyer, testing the integration between the vessel's weapons and command-and-control systems as well as its operational capability. Against this backdrop, the submarine launch can be assessed as a move to extend the operating domain of strategic cruise missiles from land and surface vessels to the underwater environment, and to secure a submarine-based strategic strike capability through the diversification of launch platforms. However, the fact that a submarine launch capability was demonstrated in this test is not sufficient to conclude that the reliability of the launch system and its actual operational capability have been secured, and further verification appears necessary.

The launch also came six days after South Korea conducted the first test launch of its indigenously developed hypersonic glide vehicle (HGV) on October 8. North Korea may therefore have sought to send a military message in response to South Korea's development of advanced strike systems, by showcasing its own submarine-based strategic strike capability.

The latest strategic cruise missile launch warrants attention not only for the emergence of the submarine as a new launch platform, but also for the implications of this platform diversification for South Korean and U.S. detection and defense systems and the increased operational burden it could impose on their forces. North Korea's strategic cruise missile development can be interpreted as moving beyond improvements in range and accuracy toward diversifying launch positions and approach directions, so as to complicate threat anticipation and response on the part of the defending side. From this perspective, the submarine launch can be assessed as an attempt to showcase an underwater launch capability, thereby widening the range of threats that the ROK and the United States must prepare for and increasing their military response burden.

Accordingly, this paper assesses trends in North Korea's strategic cruise missile development and launches, infers the purpose of the launch from technical-military and external-political perspectives, and examines the implications that the diversification of launch platforms holds for South Korea's surveillance, reconnaissance, and defense posture.

| Assessment of North Korea's Strategic Cruise Missile Development Trends

Development Trends of Strategic Cruise Missiles

Since publicizing a long-range cruise missile test launch in September 2021,²⁾ North Korea has pursued the development and performance upgrading of long-range cruise missiles for striking ground targets, including the "Hwasal-1" and "Hwasal-2." The Hwasal-1 and Hwasal-2 are understood to have a range of 1,500 to 2,000km, and North Korea has since continued development aimed at raising its operational capability, verifying long-range flight capability through repeated test launches³⁾ and diversifying launch platforms.

North Korea also announced that it "conducted the first test launch of the new strategic cruise missile 'Pulhwasal-3-31' on January 24, 2024."⁴⁾ It then conducted a further test launch of the Pulhwasal-3-31 on January 28, explicitly describing it as a test of a "submarine-launched strategic cruise missile,"⁵⁾ thereby highlighting the system's underwater launch capability and its orientation toward submarine deployment.

Some flight parameters of the Pulhwasal-3-31 were disclosed in the January 28 test launch. Rodong Sinmun reported that "two Pulhwasal-3-31 missiles were test-fired on January 28, flying over the East Sea for 7,421 seconds (2 hours 3 minutes 41 seconds) and 7,445 seconds (2 hours 4 minutes 5 seconds) respectively before hitting the target island," and released a photograph of a missile being launched at an oblique angle from underwater. However, the published photograph showed only the missile rising above the water surface, which made it difficult to confirm from the photograph alone whether the actual launch platform was a submarine or another type of underwater launch system.

On April 19 of the same year, North Korea announced that it had "conducted a test of the super-large warhead power of the 'Hwasal-1Ra-3,'" ⁶⁾ describing it as "a test for the advancement of the tactical and technical performance and operation of a new weapon system." The Hwasal-1Ra-3 appears to be an improved variant of the Hwasal-1 series with increased warhead yield. Considering these development trends of the Pulhwasal-3-31 and the Hwasal series, North Korea can be seen to have pursued development in a direction that improves the performance of existing cruise missiles while diversifying launch platforms, warheads, and operating methods.

North Korea also announced that it conducted a test launch of a sea (underwater)-to-surface strategic cruise guided weapon on January 25, 2025. Rodong Sinmun explained that "the two strategic cruise missiles launched flew for 7,507 to 7,511 seconds (approximately 2 hours 5 minutes 7 seconds and 2 hours 5 minutes 11 seconds respectively) along elliptical and figure-eight flight paths over a 1,500km flight segment before striking the target." However, the photographs published by Rodong Sinmun at the time showed only the missiles in the initial phase of flight after launch, and did not capture the moment of launch from the launcher, making it difficult to identify the launch platform actually used.

On December 28 of the same year, North Korea conducted a launch drill of long-range strategic cruise missiles over the West Sea. Rodong Sinmun stated that "the two missiles launched flew along the flight paths set over the West Sea for 10,199 seconds (2 hours 49 minutes 59 seconds) and 10,203 seconds (2 hours 50 minutes 3 seconds) respectively before hitting the target." Given that the flight trajectory pattern was similar to that of the missiles launched on January 25, while the flight time increased by more than 44 minutes, the flight performance itself appears to have been verified to a certain level. Rodong Sinmun also explained that the launch "inspected the counterstrike response posture and combat capability of long-range missile units, familiarized missile personnel with maneuver and firepower mission procedures, and checked the reliability of the strategic weapon system," which suggests that the launch system using ground-based launch platforms had entered the actual operational stage at that time.

Looking at strategic cruise missile launch trends through 2025, North Korea is assessed to have repeatedly verified long-range flight and target strike capability while focusing on checking the operational procedures of launch units and the operational reliability of the weapon system. In particular, its emphasis on expressions such as "launch drill," "inspection of counterstrike response posture," and "mastery of mission procedures" shows that the development focus for strategic cruise missiles is broadening from verifying flight performance to securing actual operational capability. Up to that point, however, North Korea had not demonstrated a submarine-based launch and operational capability.

From Ground- and Surface-Based Launches to Submarine Launches: Expansion of Launch Platforms

In 2026, North Korea expanded the launch platforms for its strategic cruise missiles to surface vessels. It announced test launches of strategic cruise missiles from the destroyer "Choe Hyon" on March 4 and 10, through KCNA and Rodong Sinmun respectively on the following day. For the March 10 launch in particular, it emphasized strikes on multiple targets and the verification of the national strategic weapons integrated command system and the destroyer's integrated combat system. On April 12, it launched two missiles⁷⁾ from the same destroyer, explaining that "the strategic cruise missiles launched as part of an operational evaluation test system flew for 7,869 to 7,920 seconds (2 hours 11 minutes 9 seconds to 2 hours 12 minutes) along the flight paths set over the West Sea before accurately striking the target." At the March 10 launch, Kim Jong Un was also reported to have "instructed that the configuration of the shipboard weapons system of destroyers to be built in the future be re-deliberated in our own way."⁸⁾ This is interpreted as a directive to review the missions and armament of future destroyers, and to consider how guns, cruise missiles, strategic cruise missiles, and other missiles should be combined and deployed to maximize combat power. These moves can be assessed as an attempt to expand surface-vessel-based strategic strike capability and widen its operational options by using destroyers as launch platforms for strategic cruise missiles, in addition to existing ground-based launch platforms.

Repeated launch drills and the review of the armament configuration can also be interpreted as a move to extend the scope of development and verification beyond the performance of individual weapons systems, toward the linkage between launchers and fire control and command-and-control systems, integrated operation with shipboard combat systems, and the establishment of mission procedures suited to actual operational environments.

Meanwhile, North Korea announced that it test-fired two types of submarine-launched strategic cruise missiles (SLCMs) in the East Sea on October 14,⁹⁾ assessing that "this launch inspected the mobilization posture of the underwater combat system, trained the navy in the performance of its strategic missions, and contributed to demonstrating the high reliability, dependability, and capability of the means of war deterrence." In this regard, the photographs released by North Korea suggest that the submarine that launched the missiles was the "Hero Kim Kun Ok," launched on September 6, 2023. Photographs of the "Hero Kim Kun Ok" made public in September 2023 had shown four large launch tubes on the upper section of the submarine, capable of launching submarine-launched ballistic missiles (SLBMs), and six smaller launch tubes capable of launching strategic cruise missiles and similar weapons.

What stands out in this launch is that, according to the photographs released by North Korean media, the two missiles used different launch systems. One appears to have been launched from a small vertical launch tube on the upper section of the submarine, and the other through a horizontal torpedo tube. Considering that North Korean media stated that "two types of submarine-launched strategic cruise missiles were test-fired," it is worth considering the possibility that submarine-launched variants of the existing Hwasal series, or the Pulhwasal-3-31 and its improved variants, were used. However, the released photographs and launch methods alone make it difficult to match the missiles fired from the vertical tube and the horizontal torpedo tube to specific series, and since North Korea did not disclose flight parameters, their specific performance also requires further confirmation.

In this connection, North Korea did not release footage of the moment of launch in its strategic cruise missile launches of January 24, 2024 and January 25, 2025, so whether those missiles were launched from a submarine could not be confirmed. Unlike the December 2025 launch, in which it showed missiles being fired from a ground-based mobile launcher, in the other launches it released only images of the initial flight in the air, without footage of the launch itself. The October 14 launch is therefore assessed as a meaningful technical advance, in that it actually demonstrated a launch capability from a submarine platform that had not previously been confirmed. It also suggests that North Korea's strategic cruise missile development is advancing beyond securing the performance of individual weapons systems toward a stage aimed at diversifying launch platforms and securing the capability to operate them in an integrated manner.

However, with regard to the "Hero Kim Kun Ok," questions have been raised since its launch about its actual operational status and the stability of its vertical launch system. It is therefore premature to conclude, from the photographs and announcement North Korea has released this time, that the launch system is stable and functioning normally. A single publicized launch success cannot confirm the performance of the missile itself or the reliability of the launch system. In particular, since only a single launch through a vertical tube was shown in this test, whether missiles can be fired in succession from multiple tubes, and whether launch success and strike accuracy are maintained in repeated underwater launch tests, remain matters requiring further confirmation. Accordingly, while North Korea's strategic cruise missile development itself can be assessed as having reached a considerable level of technical maturity, the operational reliability and actual operational capability of the submarine launch system are judged to be at a stage that requires additional verification.

| Assessing the Purpose of the Strategic Cruise Missile Launch and Its Implications

Verifying Performance Improvements and Operational Reliability as a Weapon System

North Korea stated that the October 14 test "inspected the constant mobilization posture of the underwater combat system and trained the navy in the performance of its strategic missions." The primary purpose of the launch is therefore presumed to have been to verify the technical performance of the submarine-launched strategic cruise missiles and the operational reliability of the submarine launch system.

In particular, the launch of the two missiles through a vertical launch system and a horizontal torpedo tube respectively can be seen as an attempt to confirm that different launch systems aboard the submarine can function and be operated. However, a single test is not sufficient to conclude that the stability and actual operational capability of the launch system have been adequately verified, and North Korea is expected to seek to secure reliability through repeated launches and operational tests.

The launch is therefore better assessed not as proof that the development of strategic cruise missiles has been completed, but as part of a process of testing the operational capability that links the submarine launch system with the missiles and of raising its reliability. Whether development progresses further should be judged chiefly by whether the submarine launch system operates stably in repeated tests, whether successive launches from multiple tubes are carried out smoothly, and whether post-launch flight and target strikes succeed consistently.

Diversifying Sea-Based Strike Capability and Creating Uncertainty for the Defending Side

North Korea's expansion of the launch platforms for its strategic cruise missiles from ground-based systems and surface vessels to submarines means more than a numerical increase in strike means. It diversifies the launch positions and approach directions that the defending side must take into account. If the defending side must monitor ground-based launch systems while also considering the operating waters of submarines and the possibility of underwater launches, it faces the additional task of linking platform tracking before launch with the detection of low-altitude missiles after launch. This burden may grow as the submarine's operating range widens and its stealth is secured.

From this perspective, North Korea's intent may extend beyond improving the penetration performance of individual missiles to dispersing the defending side's surveillance assets and response capabilities through the diversification of launch platforms. In particular, if ground-based, surface, and underwater launch systems are operated in combination, the defending side would have to identify threats emerging from multiple directions at once and determine response priorities. That said, it is difficult to conclude from this test alone that North Korea has secured the command-and-control and integrated operational capabilities such a combined attack would require. It will therefore be necessary to continue observing and assessing whether North Korea builds up substantive military operational capabilities, such as the ability to conduct successive launches from a submarine and to carry out operational missions.

Demonstrating Strategic Deterrence and the Possibility of External Signaling

North Korea may have sought, through this launch, to showcase its submarine-based strategic strike capability and to send a message that it is strengthening its strategic deterrent by diversifying its nuclear and missile forces. In particular, given that the launch came six days after South Korea's October 8 test launch of a hypersonic glide vehicle (HGV), it is presumed that North Korea also intended to highlight its own strike capability and to demonstrate its resolve to respond militarily to South Korea's development of advanced strike systems. That said, while noting the temporal proximity of the two tests, it is more appropriate to assess this launch not as a one-off reaction to the development of a particular weapon system, but within the context of North Korea's sustained force development, which seeks to secure diverse launch platforms, offset the ROK-U.S. military advantage, and strengthen its strategic deterrent.

By emphasizing that it can continue to conduct attacks from the sea and underwater even if its ground-based launch systems are detected and struck, North Korea can be interpreted as seeking to foster the perception that the ROK and the United States would find it difficult to neutralize its strike capability in advance. Whether North Korea has actually secured a survivable sea-based retaliatory strike capability requires separate verification. Even so, merely showcasing that it is developing such a capability can be expected to increase the military response burden on the ROK and the United States.

Assessing North Korea's Political and Strategic Purposes

North Korea's development of submarine-launched strategic cruise missiles may be linked not only to the expansion of its military strike means, but also to political and strategic purposes, namely strengthening Kim Jong Un's political standing and domestic authority, and securing a favorable position in future U.S.-North Korea negotiations.

First, by showcasing the results of developing a submarine-based strategic strike capability, North Korea is presumed to have sought to spread the perception that Kim Jong Un's policy of strengthening national defense is yielding tangible results, and to highlight his authority and leadership as the supreme leader. In particular, by promoting the continued advancement of its nuclear and missile forces and the diversification of launch platforms as Kim Jong Un's military achievements, North Korea may also have aimed to underscore the legitimacy of its defense buildup line and to elicit popular support for it, thereby consolidating internal cohesion.

Externally, North Korea's intent to accumulate the advancement of its nuclear and missile forces as a strategic asset to be used in future negotiations with the United States cannot be ruled out. In particular, by publicizing and threatening that "strategic cruise missile forces armed with tactical nuclear weapons are expanding from ground-based platforms and surface vessels to submarines," North Korea may be seeking to induce the United States to treat its possession and operation of nuclear forces as a practical condition in future negotiations.

That said, there is limited basis for judging that this launch was an act directly aimed at strengthening Kim Jong Un's domestic authority or at negotiations with the United States. The primary purpose of the launch is therefore better assessed as the verification of submarine-based strategic strike capability and the demonstration of military deterrence, with the enhancement of Kim Jong Un's political standing, the strengthening of internal cohesion, and the securing of a favorable position in future U.S.-North Korea negotiations regarded as political and strategic effects that can be expected from showcasing these military achievements.

South Korea's Response Measures

This launch shows North Korea expanding the launch platforms for its strategic cruise missiles from ground-based systems and surface vessels to submarines, in an effort to secure a submarine-based strategic strike capability. In response, South Korea needs to strengthen an integrated defense architecture that can detect and track, at an early stage, threats originating from diverse launch platforms and respond to them swiftly, rather than relying solely on the ability to intercept individual missiles. In particular, it should expand its anti-submarine surveillance and tracking capabilities and reinforce the response chain that runs from detecting signs of an underwater launch to detecting and intercepting low-altitude cruise missiles.

South Korea should also strengthen the technological capabilities of its domestic defense industry and actively pursue the development of advanced detection and interception systems capable of countering low-altitude cruise missiles and missiles approaching along diverse flight trajectories. It may also consider expanding the development of low-cost, high-efficiency interception means and multilayered defense systems that can compensate for the vulnerabilities of the existing air defense network, while broadening joint research and development in detection, command and control, and interception, building on technical cooperation between ROK and U.S. companies on integrated air defense systems.

Meanwhile, even though a submarine launch capability was demonstrated in this test, it is difficult to conclude that the stability of the launch system and its actual operational capability have been secured. It is therefore necessary to closely verify successive launch capability, the reliability of underwater launches, and the submarine's sustained operational capability, and to set response priorities according to the threat level actually confirmed.

At the political and strategic level, the ROK and the United States should maintain close coordination in order to jointly assess the impact of North Korea's diversification of its nuclear and missile forces on the security of the Korean Peninsula and on future negotiations with North Korea, and to formulate a consistent response. In particular, to ensure that the diversification of North Korea's nuclear and missile forces is not used in future U.S.-North Korea negotiations as a means of winning de facto tolerance of its nuclear status or one-sided concessions, the two countries should strengthen prior consultations on negotiating objectives and verification principles.

1. KCNA, October 15, 2026
2. Rodong Sinmun, September 13, 2021: Reported that North Korea "successfully test-fired new long-range cruise missiles with a range of 1,500km on September 11 and 12," and explained that "the long-range cruise missiles launched flew for 7,580 seconds (2 hours 6 minutes 20 seconds) along elliptical and figure-eight flight paths set over the territory and territorial waters of our country, and hit the target at the 1,500km line."
3. Sept. 11-12, 2021: Assessed as Hwasal-1; two missiles; elliptical and figure-eight trajectories; 1,500km
   Jan. 25, 2022: Assessed as Hwasal-2; two missiles; along a flight path set over the East Sea; 1,800km; 2 hours 32 minutes 17 seconds
   Oct. 12, 2022: Launched from Kaechon, South Pyongan Province, toward the West Sea; assessed as Hwasal-2; two missiles; 2,000km; 2 hours 50 minutes 34 seconds
   Feb. 23, 2023: Launched from Kimchaek, North Hamgyong Province, toward the East Sea; Hwasal-2; four missiles; 2,000km; 2 hours 50 minutes 8 seconds to 24 seconds
   Mar. 22, 2023: Launched from Hamhung, South Hamgyong Province, toward the East Sea; two Hwasal-1 and two Hwasal-2 missiles; Hwasal-1 at 1,500km, Hwasal-2 at 1,800km
   (Cases that are difficult to confirm as Hwasal-1 or Hwasal-2)
   Aug. 17, 2022: Launched from Onchon, South Pyongan Province, toward the West Sea; not announced by North Korea; detected and made public by the ROK military
   Nov. 2, 2022: North Hamgyong region; North Korea claimed two strategic cruise missiles, but the ROK JCS stated that no cruise missiles had been detected
   Mar. 12, 2023: Two missiles launched from the vessel "Hero 824" near Sinpo; North Korea claimed the strategic cruise missiles flew for more than two hours over 1,500km
   Jul. 22, 2023: Several missiles launched toward the West Sea; detected by the JCS but flight parameters not disclosed; possibly of the Hwasal series
   Aug. 21, 2023: Reported as launched from Patrol Ship No. 661 of the East Sea Fleet; North Korea announced it as a "strategic cruise missile launch drill," but the ROK military assessed that it was not a launch of the Hwasal series
   Sept. 2, 2023: Launched from the Chongchon River estuary toward the West Sea; two long-range cruise missiles; North Korea claimed they flew a 1,500km figure-eight trajectory for 2 hours 7 minutes 52 seconds to 2 hours 8 minutes 1 second, then detonated in the air at an altitude of 150m
4. KCNA, January 25, 2024
5. KCNA, January 29, 2024
6. KCNA, April 20, 2024
7. Rodong Sinmun, April 14, 2026
8. Rodong Sinmun, April 14, 2026
9. KCNA, October 15, 2026

※ The opinions expressed in 'Sejong Focus' are those of the author and do not represent the official views of Sejong Institute.