Column / Report / Other Papers

[Research Reports] The Current Stage of North Korea's "Tactical Nuclear Weapons" Development -The Utility of the KN-23 Missile and Diversification

Hideya Kurata (Professor, Director of Global Security Center, National Defense Academy / Adjunct Fellow, Japan Institute of International Affairs)
  • twitter
  • Facebook

Research Group on 'Korean Peninsula' FY2021-# 4

"Research Reports" are compiled by participants in research groups set up at the Japan Institute of International Affairs, and are designed to disseminate, in a timely fashion, the content of presentations made at research group meetings or analyses of current affairs. The "Research Reports" represent their authors' views. In addition to these "Research Reports", individual research groups will publish "Research Bulletins" covering the full range of the group's research themes.

1. Introduction- "The accuracy-vulnerability paradox"

Many of the ballistic missiles launched by North Korea during the "Third North Korea Nuclear Crisis" from 2016 to 2017 were designed to target large cities in countervalue attacks that would cause extensive damage and casualties, and this resulted in their "completion" of intercontinental ballistic missiles (ICBMs) in November 2017. On the other hand, many of the missiles that North Korea has launched since the second US-North Korea summit meeting in February 2019, considering their flight distance, have been intended for counterforce attacks to accurately hit relatively small targets such as the headquarters of United States Forces Korea (USFK). These are weapons for counterforce attacks to prevent USFK intervention if an armed conflict within the Korean Peninsula escalates to the point of such intervention.

Certainly, North Korea had deployed short-range missiles since the Cold War period, but those missiles (the Scud-B was called the Hwasong-5, and the Scud-C the Hwasong-6) belonged to the Hwasong series, which had been developed with liquid fuels that lacked launch readiness. Moreover, during that time, many USFK bases were moved further south under a relocation plan starting from the Bush administration. Therefore, it was unlikely that Scud-series missiles could immediately attack USFK bases that had relocated southward during an armed clash inside the Korean Peninsula. In particular, the Scud-series missiles lacked the ability to accurately hit small targets such as the USFK headquarters relocated to Pyeongtaek, 80 kilometers south of Seoul.

On the other hand, North Korea has developed the solid-fueled KN-02 ("Toksa") as a short-range missile to succeed the Scud series and extended its range to put the USFK headquarters relocated to Pyeongtaek within striking distance, and already completed its operational deployment. However, the KN-02's extended range and increased accuracy will make the missile's trajectory clearer and relatively easier to intercept from the perspective of the USFK. The higher the hit rate, the easier it is for ballistic missiles to be intercepted; how is North Korea trying to escape this paradox?

One way to do so is to change the missile's trajectory from a simple ballistic trajectory to an irregular one. North Korea's missiles fired over the past two years include a modified version of the solid-fueled KN-23 modeled after Russia's Iskander-M. Although the KN-23 is a ballistic missile, it takes an irregular trajectory by performing a "pull-up" maneuver when descending after reaching apogee. As a result, North Korea is trying to avoid interception by disrupting ballistic calculations while improving the accuracy of missile hits.

2. The equivocation behind "making nuclear weapons tactical" - Kim Jong-un's report to the 8th WPK Congress

The KN-23 was displayed at a military parade for the 8th Congress of the Workers' Party of Korea (WPK) in January 2021upon a transporter-erector-launcher (TEL) of 5-axis 10-wheel model, an enlarged version of a TEL of 4-axis 8-wheel model for the Iskander-M. Its first test launch was the "strike drill" in early May 2019. The KN-23 was launched again on July 25 of the same year, and the Korean Central News Agency (KCNA) called this a test-launch of a "new type of tactical guided weapon" and revealed that the KN-23 features a "low-altitude gliding and leaping orbit". Although the Russian Iskander-M, after which the KN-23 was modeled, can be equipped with both nuclear and conventional warheads, it is unlikely that the KN-23 was designed to be equipped with a nuclear warhead. When the Hwasong-9 (Scud-ER or Scud-D) was launched in March 2017, the KN-02 had already been operationally deployed, but the Rodong Sinmun published a commentary saying, "Japan will be the first nation enveloped in a cloud of radioactivity." When the KN-23 was launched, the KCNA consistently reported that it was a test of "firepower strike" and "firepower response" capabilities, and "firepower" was translated into "bombardment" for its Japanese-language coverage.

However, it must be considered that North Korea had in mind the development of tactical nuclear weapons from the beginning. After the Supreme People's Assembly adopted the Law on Consolidating the Position of Nuclear Weapons State for Self-defense in April 2013 and clarified the outline of a "nuclear doctrine", the Rodong Sinmun (May 21, 2013) published a commentary pointing out the respective utilities of "strategic nuclear weapons" and "tactical nuclear weapons." This commentary described a strategic nuclear weapon as a "weapon consisting of a nuclear bomb and its delivery means for hitting strategic objects such as the industrial centers of an adversary's major cities, command centers and nuclear weapon batteries", emphasizing its function in countervalue attacks; and it defined a "tactical nuclear weapon" as "a weapon consisting of a nuclear bomb and its delivery means for hitting manpower and firepower, tanks, ships, command centers, etc., on front lines and tactical operations centers", emphasizing its "accuracy" as a counterforce weapon. Kim Jong-un also reported at the 8th Congress of the WPK in January 2021 that success had been achieved in "miniaturizing, lightening and standardizing nuclear weapons to make them tactical ones and completing the development of a super-large hydrogen bomb" as "achievements made in the period" since the 7th WPK Congress in May 2016, suggesting that a tactical nuclear weapon had already been completed.

However, it should be noted that Kim Jong-un referred there to miniaturizing nuclear weapons and developing a super-large hydrogen bomb in the same context. Needless to say, a nuclear weapon regardless of its range must be made smaller and lighter in order to turn it into a warhead. At the time of the fifth nuclear test in September 2016, the Nuclear Weapons Institute of North Korea said in a statement,"the standardization of nuclear warheads will enable the DPRK to produce at will as many as it wants of a variety of smaller, lighter and diversified nuclear warheads of higher strike power." Kim Jong-un thus described "tactical nuclear weaponization" in the same context as "the miniaturization" of nuclear weapons, and it is unlikely that North Korea has completed its counterforce capabilities by installing low-yield nuclear warheads on KN-02 and KN-23 missiles.

In fact, Kim Jong-un in his report also referred to "tactical nuclear weapons" in the section describing "the core plans and strategic tasks of crucial importance in rapidly developing and strengthening the national defense industry" (hereinafter "strategic tasks"), stating "It is make nuclear weapons smaller and lighter for more tactical uses. This will make nuclear weapons to be used as various means according to the purposes of operational duty and targets if strike in modern warfare." The "tactical nuclear weaponization" mentioned by Kim Jong-un at the 8th WPK Congress should still perhaps be seen as having been set as a future objective.

3. KN-23 as a transitional weapon - two directions

(1) Launch of "new-type tactical guided projectiles" - remarks by Kim Yo-jong and Ri Pyong-chol

On March 25, 2021, the Academy of Defense Science launched two ballistic missiles, believed to have been KN-23 missiles that it called "newly developed new-type tactical guided projectiles", from the vicinity of Hamju, South Hamgyong Province. North Korea had never previously announced the flight distance in KN-23 test launches, but exclusively in this case, the KCNA announced that the launched KN-23s had "accurately hit targets set in the waters 600 kilometers off the coast of Korea." Most of the KN-23s fired so far - except for the second one fired on July 25, 2019 that was observed to have flown about 690 km - have been observed to travel less than 450 km. In light of this, it can be surmised that the KN-23 missiles used this time had been enlarged. According to the image distributed by the KCNA, the TEL used this time seems to have been the 5-axis 10-wheel model - the same as the one appeared loaded with the KN-23 in the military parade for the 8th WPK Congress, enlarged from the 4-axis 8-wheel TEL of the Iskander-M.

The KN-23s launched in this instance are said to have been "weapon systems with an improved warhead weight of 2.5 tons". The 2.5-ton warhead weight (payload) is estimated to be more than twice that of the warhead on the Hwasong-7 (Nodong) intermediate-range nuclear missile (about 700 kg to 1200 kg), and it is unlikely that it was designed to carry a nuclear warhead. Immediately after this, Kim Jong-un's younger sister Kim Yo-jong (Vice Director of the Party Central Committee's Information and Publicity Department), denounced ROK President Moon Jae-in's remarks in July 2020 that "we have reached the point of developing ballistic missiles with sufficient ranged and capable of carrying some of the world's largest warheads" as "illogical and brazen-faced behavior." She must have bore in mind then-ROK Defense Minister Jeong Kyeung-doo's announcement in July 2019 regarding Hyungmoo-4 to have range of 800 km and a two-tons warhead. North Korea was likely trying to show off a payload that surpassed that of South Korea's Hyunmoo-4 on the presumption it was carrying a conventional warhead.

It should be pointed out here that Ri Pyong-chol, a member of the Presidium of the Politburo of the WPK Central Committee (at that time) described this test launch as "an important process in implementing the policy of national defense science set forth at the 8th Congress of the WPK." This "policy of national defense science" refers to the "strategic tasks" that Kim Jong-un brought up at the 8th WPK Congress, and the recently launched KN-23, described as this "process", means that it was not a completed version.

(2) "Railway-borne missile system" - an alternative to Hwasong-9

In this context, the missiles launched from the "railway-borne missile system" on September 15, 2021 will need to be examined. Two missiles were fired from a launch pad loaded on a single railroad car, which are also considered to be improved versions of the KN-23. Launches from railroad vehicles enable launch confidentiality and multiple simultaneous launches, but greater emphasis should be placed on the flight distance. According to the KCNA, the KN-23s launched on this occasion "accurately struck the target in the sea 800 km away" in the Sea of ​​Japan. If so, it is probable that the KN-23s launched from the railway-borne missile system were even larger than the KN-23 launched on March 25, which had flown about 600 kilometers.

If this missile has a range of about 800 km, it can cover the US's Sasebo Naval Base and Marine Corps Air Station Iwakuni, which were used as combat bases for UN forces during the Korean War. The aforementioned Hwasong-9 was observed to have a range of about 1000 km, and North Korea did not hide its intention to target US bases in Japan, but the Hwasong-series ballistic missiles were developed to use liquid fuel and the Hwasong-9 also used liquid fuel as a propellant. On the other hand, if the KN-23s launched from the railway-borne missile system are not a finalized version but a transitional model, like the KN-23 launched on March 25, the range of some of these missiles will be extended to cover USFJ bases even if most of them are deployed as tactical missiles aimed at USFK bases. Given that the KN-23 is propelled by solid fuel, it can serve as a new launch-ready intermediate-range nuclear missile targeting US bases in Japan if it is equipped with a nuclear warhead.

4. Conclusion The "Pakistanization" of North Korea's nuclear posture

Since the second US-North Korea summit meeting in Hanoi ended without any outcome document, a series of launch tests conducted by North Korea have been almost consistently designed to "prevent escalation," i.e., keep an armed clash in the demilitarized zone (DMZ) from leading to intervention by USFK and preventing USFJ from getting involved if that fails. The cruise missiles launched on September 11 and 12, 2021 and the Hwasong-8 hypersonic gliding missiles launched on September 28 can also be considered weapons for "preventing escalation." At the 8th WPK Congress, Kim Jong-un emphasized, "It is necessary to...thoroughly contain, control and handle various military threats on the Korean peninsula which are inevitably accompanied by the nuclear threat." This suggests that North Korea, which has less conventional military strength than the ROK/US Combined Forces Command (CFC), is preparing a system to deter US military intervention at each stage of "escalation" while suggesting the option of a preemptive nuclear strike.

Such a nuclear posture resembles that of Pakistan. Pakistan's nuclear posture, also known as "asymmetric escalation" (V. Narang), is a strategy in which Pakistan, which is in an asymmetrical (inferior) situation vis-à-vis India in terms of conventional military strength, attempts to deter India's conventional forces by showing its willingness to use preemptive nuclear strikes and its readiness to escalate a conflict. India, on the other hand, is trying to deter Pakistan's use of nuclear weapons with "Credible Minimum Deterrence" that promises mass retaliation against any nuclear attack while declaring no-first use (NFU) of nuclear weapons, but Pakistan has already deployed low-yield tactical nuclear weapons. If Pakistan were to use these tactical nuclear weapons, India would have to make a countervalue attack on Pakistan if it wants to remain faithful to "Credible Minimum Deterrence". Pakistan would then likely launch a countervalue attack on India. Must India take the risk of a countervalue retaliation against Pakistan's use of low-yield nuclear weapons, or should it try to deter Pakistan's use of tactical nuclear weapons by indicating its willingness to use a proportionate type of nuclear weapon? India is said to be reexamining its own nuclear posture, largely due to Pakistan's tactical nuclear weapons.

North Korea has so far suggested that early use of nuclear weapons would prevent escalation. But if North Korea possesses tactical nuclear weapons, its nuclear posture will eventually become "Pakistanized." Moreover, its weapons follow irregular trajectories to disrupt ROK/US CFC's missile defenses, and this may compel the United States to reconsider not only missile defense but also the US-ROK deterrence posture. Of course, the United States is not in a "Minimum Deterrence" posture like India. However, it has been a long time since tactical nuclear weapons were removed from USFK, and US forces in Japan have no nuclear weapons. The geographically closest nuclear weapons are those onboard strategic bombers at Andersen Air Force Base, Guam. If North Korea comes to possess tactical nuclear weapons, serious questions must be raised about the ability to deter their early use.

<Key references>

Rodong Sinmun/Korean Central News Agency/Pyongyang Times/『朝鮮民主主義人民共和国月刊論調』/『朝鮮新報』

Vipin Narang, Nuclear Strategy in the Modern Era: Regional Powers and International Conflict, Princeton: Princeton University Press, 2014

Diana Wueger, "Pakistan's Nuclear Future: Continued Dependence on Asymmetric Escalation,"Nonproliferation Review , Volume 26, Issues 5-6 (2019)





Hideya Kurata, "Formation and Evolution of Kim Jong Un's "Nuclear Doctrine": The Current State of North Korea's "Minimum Deterrence" in Comparison," The Kim Jong Un Regime and the Future Security Environment Surrounding the Korean Peninsula, Tokyo: The National Institute for Defense Studies, 2017

___________, "North Korea's Nuclear Weapon Capabilities: Emerging Escalation Ladder," CSCAP Regional Security Outlook, Canberra: Council for Security Cooperation in the Asia Pacific, 2017

___________, "Kim Jong-un's Nuclear Posture under Transformation: The Source of North Korea's counterforce Compulsion," Hideya Kurata and Jerker Hellström (eds.), North Korea's Security Threats Reexamined, Yokosuka: National Defense Academy, 2019

___________, "Escaping from the 'Accuracy-Vulnerability Paradox': The DPRK's Initial Escalation Ladders in War Strategy," Hideya Kurata and Jerker Hellström (eds.), Nuclear Threshold Lowered?  Yokosuka: National Defense Academy, 2021, etc.,

(This is English translation of modified Japanese paper originally published on November 10,2021)