Editor’s Note: In advance of Japanese Prime Minister Takaichi’s planned visit to Washington this month, three Japanese scholars offer their views on how and why complete denuclearization should be emphasized in Japanese, South Korean, and American policy toward North Korea. Key points of this commentary are developed further in Japanese in “Kitachosen Kaku-misairu Risuku no Sogo-bunseki” (“Comprehensive Analysis of North Korea’s Nuclear and Missile Risks”), Japan Institute of International Affairs (forthcoming, March 2026).
All three authors will appear at a public event on March 17, in-person and online. To join us, register here.
Andrew Oros, Senior Fellow and Director, Japan Program
North Korea is attempting to deter the escalation of conflict on the Korean Peninsula into a full-scale war by threatening to use tactical nuclear weapons. There is no guarantee that this will succeed. North Korean Supreme Leader Kim Jong-un’s reference to “deterrence failure” at the end of 2022 implies that he assumes battles will follow a failure of deterrence. How does North Korea intend to fight that conflict? Two strategies outlined by Kim Jong-un provide some clues. Yet, the U.S. approach to deterring that conflict must also be examined to advance a coordinated solution to achieve the complete denuclearization of the Korean peninsula — a policy goal that has failed to date. This is particularly important in the context of increased U.S. escalation of military interventions elsewhere in the world.
It is inappropriate for the United States to deploy a nuclear force that would end the regime in Pyongyang as retaliation for North Korea’s use of tactical nuclear weapons. Such a show of force would provoke retaliatory attacks on Seoul, Tokyo, and Washington, given North Korea’s surviving second-strike capability. We must avoid suffering intolerable damage in response to North Korea’s use of tactical nuclear weapons. It is important to make North Korea realize that using tactical nukes will provoke appropriate retaliation, and to prevent them from using medium-range nuclear weapons or ICBMs. That is why it is argued that the United States should have escalation dominance at sea.
Two Nuclear Strategies and Failure of Deterrence
Kim Jong-un presented two strategies in his speech at the March 2013 plenary meeting of the Workers’ Party of Korea (WPK) Central Committee: the “War Deterrence Strategy” and the “War Strategy.” While “war deterrence” is used more broadly in Kim Jong-un’s discourse when referring to strategies, the terms “war deterrence strategy” and “war strategy” corresponded to North Korea’s war scenarios. The “war deterrence strategy” corresponds to “minimum deterrence” attempting to prevent direct nuclear attack from the United States. It pledges a no-first-use of nuclear weapons policy and commits to retaliatory countervalue strikes with second-strike capabilities in the event of a nuclear attack. In contrast, the “war strategy” envisions a localized war scenario in which the threat of nuclear use is employed to prevent an armed conflict between North and South Korea from escalating into full-scale war.
Under this strategy, the actual use of nuclear weapons is not ruled out if armed conflict between North and South Korea escalates despite threatening to use nuclear weapons. The nuclear forces employed would be tactical nuclear weapons with restricted explosive yields, designed for counterforce attacks as an extension of conventional forces. If North Korea were to use tactical nuclear weapons that neither the United States nor the South Korean military possesses, it would constitute a first strike. Development of tactical nuclear weapons was also listed as a top priority in the “Five-Year National Defense Plan” announced after the 8th Congress of the WPK in January 2021. Furthermore, on December 31, 2022, at the 6th Plenary Meeting of the 8th Central Committee of the WPK, Kim Jong-un pointed out, “Nuclear Force considers it as the first mission to deter war and safeguard peace and stability and, however, if it fails to deter, it will carry out the second mission, which will not be for defense,” suggesting that the Korean Peninsula would enter a state of combat.
At last month’s 9th Congress of the WPK Korea, Kim Jong-un stated that “it is of very great significance to rapidly and continuously modernize naval operational capabilities, focusing on the nuclear armament of the navy’s surface and underwater forces.” He added: “We are planning to strengthen our nuclear forces year by year and will devote all efforts to increasing the number of nuclear weapons and expanding the means of nuclear deployment and spaces of utilization.”
‘Assumed Battles’ After Failed De-escalation
The United States and North Korea are in a state where asymmetric mutual nuclear deterrence is taking effect. Rather than considering missile defense for damage limitation, North Korea is focusing its efforts on developing weapon systems for countervalue retaliatory attacks. On the other hand, in the “war strategy,” which envisions a war between the North and South with localized conventional forces, even in the case that a war breaks out on the Korean Peninsula, it does not mean the collapse of the North Korean regime. However, if it escalates into an all-out war due to the intervention of U.S. forces in Korea, it is hard to imagine that North Korea’s regime would survive considering the inferiority of its conventional forces compared to the US-ROK combined forces.
Expansion of Tactical Nuclear Operations: Space to the Sea
At the Supreme People’s Assembly in September 2022, which adopted the “Nuclear Use Ordinance,” Kim Jong-un pointed out the need to “steadily expand the operational space of tactical nukes,” followed by intensive “tactical nuclear operational unit military training” that was conducted. In the exercise on September 25, 2022, a “launch test of a ballistic missile simulating a tactical nuclear warhead” was conducted from a “northwest reservoir underwater launch site” and the “ballistic missile launch exercise” on September 28 also was carried out with the aim of “neutralizing airfields within South Korea’s operational area.”
Although these were land-based exercises, in the event that a war between the North and South escalates, the theater of war might expand from land to sea. As the Korean War invited United Nations military intervention and troops were provided from Japan, in a case of prolonged land-based war, U.S. naval forces in Japan and the U.S. 7th Fleet could become involved in addition to U.S. forces in South Korea. Naval battles developed from the land war on the Korean Peninsula, and the failure of deterrence Kim Jong-un referred to at the 6th Plenary Meeting of the 8th Central Committee of WPK in 2021 pointed to such a scenario.
It is worth noting that when the unmanned underwater nuclear attack craft Haeil was tested in March 2023, its operational deployment was reportedly decided at the 6th Plenary Meeting of the 8th Central Committee in December 2022. The mission of Haeil is reported to be to “stealthily infiltrate into operational waters and make a super-scale radioactive tsunami through underwater explosion to destroy naval striker groups and major operational ports of the enemy.” At that time, the military reconnaissance satellite Malligyong was already being tested, implying that North Korea could track U.S. vessels moving from the Pacific towards the Korean Peninsula in real time and prevent their approach by combining Haeil with Malligyong.
It was also reported around the same time that the 6th Plenary Meeting of the 8th Central Committee had made important decisions regarding the potential failure of deterrence. When Kim Jong-un guided the work for mounting nuclear warheads on ballistic missiles on March 27, 2023, it was reported that the Nuclear Weapons Institute reported to Kim Jong Un on recent years’ work in accordance with the orientation of developing nuclear weapons and strategic policy set forth at the 8th Congress of the WPK and the 6th Plenary Meeting of the 8th Central Committee of the WPK. The orientation of developing nuclear weapons and strategic policy, as indicated by the 6th Plenary Meeting of the 8th Central Committee, is also supposed to envisage naval battles as part of a war following a failure of deterrence. Assuming that the failure of deterrence that Kim Jong-un refers to presumes naval battles, the orientation of developing nuclear weapons and strategic policy would also have assumed a naval battle. A tactical nuclear warhead Hwasan-31 revealed in this report may be loaded onto Haeil.
In this context, the launch of the tactical nuclear attack submarine Hero Kim Kun Ok on September 6, 2023 is also noteworthy. The Hero Kim Kun Ok was designed to be able to launch submarine-launched ballistic missiles (SLBMs) and six submarine-launched cruise missiles (SLCMs), as it was reported as a tactical nuclear attack submarine, it was clear that the nuclear force it carries would be tactical nuclear weapons. If the Hero Kim Kun Ok is armed with the tactical nuclear warhead Hwasan-31 and equipped with the unmanned and underwater Haeil nuclear attack craft, the operational space of tactical nukes would extend underwater.
Furthermore, on April 25, 2025, the destroyer Choe Hyon was launched. Kim Jong-un stated here that “it has now become possible to increase the possibility of direct intervention by the Navy in ground operations,” indicating that the Korean People’s Army and Navy can share similar weapons systems, enabling naval operations as an extension of ground combat when ground combat escalates into naval warfare. Kim Jong-un also stated that Choe Hyon is equipped with weapons systems capable of maximizing land-attack capabilities, including hypersonic strategic cruise missiles, tactical ballistic missiles, and other means of strikes. Considering that the Choe Hyon-class destroyer carries tactical nuclear strike capabilities of the Korean People’s Army, its production would extend the operational space of tactical nuclear weapons to the maritime domain.
Conclusion
While complete denuclearization of the Korean peninsula is a laudable goal, North Korea is currently moving in the opposite direction. North Korea now holds escalation dominance on the Korean Peninsula’s land and near-shore waters in part because of its nuclear weapons capabilities. The United States must deter North Korea’s tactical nuclear use with commensurate strike capabilities. The U.S. Navy possesses no nuclear strike capability at sea, and its submarine-based nuclear strike capability consists almost entirely of countervalue strikes, which would provoke North Korea to activate its second-strike capabilities. The only tactical nuclear weapons the United States has covertly deployed under the sea are the 5-kiloton W76-2 warheads deployed on SLBMs under the first Trump administration’s Nuclear Posture Review. These U.S. submarine-based tactical nuclear weapons could be considered a commensurate deterrent against North Korea’s use of tactical nuclear weapons.
About the Author
Hideya Kurata is Dean of the Graduate School of Security Studies and Professor in the Department of International Relations at the National Defense Academy of Japan and an Adjunct Research Fellow at the Japan Institute of International Affairs. His recent works include “China’s Use of Influence in the Indo-Pacific: Patterns and Regional Insights,” Yokosuka: National Defense Academy, 2024 (co-edited).
Addressing the Tactical Nukes Challenge in North Korea’s ‘Assumed Battles’ Scenario
By Hideya Kurata
Korean Peninsula
Editor’s Note: In advance of Japanese Prime Minister Takaichi’s planned visit to Washington this month, three Japanese scholars offer their views on how and why complete denuclearization should be emphasized in Japanese, South Korean, and American policy toward North Korea. Key points of this commentary are developed further in Japanese in “Kitachosen Kaku-misairu Risuku no Sogo-bunseki” (“Comprehensive Analysis of North Korea’s Nuclear and Missile Risks”), Japan Institute of International Affairs (forthcoming, March 2026).
All three authors will appear at a public event on March 17, in-person and online. To join us, register here.
Andrew Oros, Senior Fellow and Director, Japan Program
North Korea is attempting to deter the escalation of conflict on the Korean Peninsula into a full-scale war by threatening to use tactical nuclear weapons. There is no guarantee that this will succeed. North Korean Supreme Leader Kim Jong-un’s reference to “deterrence failure” at the end of 2022 implies that he assumes battles will follow a failure of deterrence. How does North Korea intend to fight that conflict? Two strategies outlined by Kim Jong-un provide some clues. Yet, the U.S. approach to deterring that conflict must also be examined to advance a coordinated solution to achieve the complete denuclearization of the Korean peninsula — a policy goal that has failed to date. This is particularly important in the context of increased U.S. escalation of military interventions elsewhere in the world.
It is inappropriate for the United States to deploy a nuclear force that would end the regime in Pyongyang as retaliation for North Korea’s use of tactical nuclear weapons. Such a show of force would provoke retaliatory attacks on Seoul, Tokyo, and Washington, given North Korea’s surviving second-strike capability. We must avoid suffering intolerable damage in response to North Korea’s use of tactical nuclear weapons. It is important to make North Korea realize that using tactical nukes will provoke appropriate retaliation, and to prevent them from using medium-range nuclear weapons or ICBMs. That is why it is argued that the United States should have escalation dominance at sea.
Two Nuclear Strategies and Failure of Deterrence
Kim Jong-un presented two strategies in his speech at the March 2013 plenary meeting of the Workers’ Party of Korea (WPK) Central Committee: the “War Deterrence Strategy” and the “War Strategy.”1Rodong Sinmun, April 1, 2013. While “war deterrence” is used more broadly in Kim Jong-un’s discourse when referring to strategies, the terms “war deterrence strategy” and “war strategy” corresponded to North Korea’s war scenarios. The “war deterrence strategy” corresponds to “minimum deterrence” attempting to prevent direct nuclear attack from the United States. It pledges a no-first-use of nuclear weapons policy and commits to retaliatory countervalue strikes with second-strike capabilities in the event of a nuclear attack. In contrast, the “war strategy” envisions a localized war scenario in which the threat of nuclear use is employed to prevent an armed conflict between North and South Korea from escalating into full-scale war.2See 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, The National Institute for Defense Studies, 2017.
Under this strategy, the actual use of nuclear weapons is not ruled out if armed conflict between North and South Korea escalates despite threatening to use nuclear weapons. The nuclear forces employed would be tactical nuclear weapons with restricted explosive yields, designed for counterforce attacks as an extension of conventional forces. If North Korea were to use tactical nuclear weapons that neither the United States nor the South Korean military possesses, it would constitute a first strike. Development of tactical nuclear weapons was also listed as a top priority in the “Five-Year National Defense Plan” announced after the 8th Congress of the WPK in January 2021. Furthermore, on December 31, 2022, at the 6th Plenary Meeting of the 8th Central Committee of the WPK, Kim Jong-un pointed out, “Nuclear Force considers it as the first mission to deter war and safeguard peace and stability and, however, if it fails to deter, it will carry out the second mission, which will not be for defense,” suggesting that the Korean Peninsula would enter a state of combat.3Rodong Shinmun, January 1, 2023.
At last month’s 9th Congress of the WPK Korea, Kim Jong-un stated that “it is of very great significance to rapidly and continuously modernize naval operational capabilities, focusing on the nuclear armament of the navy’s surface and underwater forces.” He added: “We are planning to strengthen our nuclear forces year by year and will devote all efforts to increasing the number of nuclear weapons and expanding the means of nuclear deployment and spaces of utilization.”
‘Assumed Battles’ After Failed De-escalation
The United States and North Korea are in a state where asymmetric mutual nuclear deterrence is taking effect. Rather than considering missile defense for damage limitation, North Korea is focusing its efforts on developing weapon systems for countervalue retaliatory attacks. On the other hand, in the “war strategy,” which envisions a war between the North and South with localized conventional forces, even in the case that a war breaks out on the Korean Peninsula, it does not mean the collapse of the North Korean regime. However, if it escalates into an all-out war due to the intervention of U.S. forces in Korea, it is hard to imagine that North Korea’s regime would survive considering the inferiority of its conventional forces compared to the US-ROK combined forces.
Expansion of Tactical Nuclear Operations: Space to the Sea
At the Supreme People’s Assembly in September 2022, which adopted the “Nuclear Use Ordinance,” Kim Jong-un pointed out the need to “steadily expand the operational space of tactical nukes,” followed by intensive “tactical nuclear operational unit military training” that was conducted. In the exercise on September 25, 2022, a “launch test of a ballistic missile simulating a tactical nuclear warhead” was conducted from a “northwest reservoir underwater launch site” and the “ballistic missile launch exercise” on September 28 also was carried out with the aim of “neutralizing airfields within South Korea’s operational area.”4“Kim Jong Un Guides Military Exercises of KPA Units for Operation of Tactical Nuke,” Pyongyang Times, October 15, 2022; “Special Report: Political Measures Taken to Signally Bolster Up War Deterrent as Required by Prevailing Situation on Korean Peninsula,” Democratic People’s Republic of Korea, November, 2022, p. 66.
Although these were land-based exercises, in the event that a war between the North and South escalates, the theater of war might expand from land to sea. As the Korean War invited United Nations military intervention and troops were provided from Japan, in a case of prolonged land-based war, U.S. naval forces in Japan and the U.S. 7th Fleet could become involved in addition to U.S. forces in South Korea. Naval battles developed from the land war on the Korean Peninsula, and the failure of deterrence Kim Jong-un referred to at the 6th Plenary Meeting of the 8th Central Committee of WPK in 2021 pointed to such a scenario.
It is worth noting that when the unmanned underwater nuclear attack craft Haeil was tested in March 2023, its operational deployment was reportedly decided at the 6th Plenary Meeting of the 8th Central Committee in December 2022. The mission of Haeil is reported to be to “stealthily infiltrate into operational waters and make a super-scale radioactive tsunami through underwater explosion to destroy naval striker groups and major operational ports of the enemy.”5Rodong Shinmun, April 24, 2023. At that time, the military reconnaissance satellite Malligyong was already being tested, implying that North Korea could track U.S. vessels moving from the Pacific towards the Korean Peninsula in real time and prevent their approach by combining Haeil with Malligyong.
It was also reported around the same time that the 6th Plenary Meeting of the 8th Central Committee had made important decisions regarding the potential failure of deterrence. When Kim Jong-un guided the work for mounting nuclear warheads on ballistic missiles on March 27, 2023, it was reported that the Nuclear Weapons Institute reported to Kim Jong Un on recent years’ work in accordance with the orientation of developing nuclear weapons and strategic policy set forth at the 8th Congress of the WPK and the 6th Plenary Meeting of the 8th Central Committee of the WPK. The orientation of developing nuclear weapons and strategic policy, as indicated by the 6th Plenary Meeting of the 8th Central Committee, is also supposed to envisage naval battles as part of a war following a failure of deterrence. Assuming that the failure of deterrence that Kim Jong-un refers to presumes naval battles, the orientation of developing nuclear weapons and strategic policy would also have assumed a naval battle. A tactical nuclear warhead Hwasan-31 revealed in this report may be loaded onto Haeil.
In this context, the launch of the tactical nuclear attack submarine Hero Kim Kun Ok on September 6, 2023 is also noteworthy. The Hero Kim Kun Ok was designed to be able to launch submarine-launched ballistic missiles (SLBMs) and six submarine-launched cruise missiles (SLCMs), as it was reported as a tactical nuclear attack submarine, it was clear that the nuclear force it carries would be tactical nuclear weapons. If the Hero Kim Kun Ok is armed with the tactical nuclear warhead Hwasan-31 and equipped with the unmanned and underwater Haeil nuclear attack craft, the operational space of tactical nukes would extend underwater.
Furthermore, on April 25, 2025, the destroyer Choe Hyon was launched. Kim Jong-un stated here that “it has now become possible to increase the possibility of direct intervention by the Navy in ground operations,”6Rodong Shinmun, April 26, 2025. indicating that the Korean People’s Army and Navy can share similar weapons systems, enabling naval operations as an extension of ground combat when ground combat escalates into naval warfare. Kim Jong-un also stated that Choe Hyon is equipped with weapons systems capable of maximizing land-attack capabilities, including hypersonic strategic cruise missiles, tactical ballistic missiles, and other means of strikes. Considering that the Choe Hyon-class destroyer carries tactical nuclear strike capabilities of the Korean People’s Army, its production would extend the operational space of tactical nuclear weapons to the maritime domain.
Conclusion
While complete denuclearization of the Korean peninsula is a laudable goal, North Korea is currently moving in the opposite direction. North Korea now holds escalation dominance on the Korean Peninsula’s land and near-shore waters in part because of its nuclear weapons capabilities. The United States must deter North Korea’s tactical nuclear use with commensurate strike capabilities. The U.S. Navy possesses no nuclear strike capability at sea, and its submarine-based nuclear strike capability consists almost entirely of countervalue strikes, which would provoke North Korea to activate its second-strike capabilities. The only tactical nuclear weapons the United States has covertly deployed under the sea are the 5-kiloton W76-2 warheads deployed on SLBMs under the first Trump administration’s Nuclear Posture Review. These U.S. submarine-based tactical nuclear weapons could be considered a commensurate deterrent against North Korea’s use of tactical nuclear weapons.
About the Author
Hideya Kurata is Dean of the Graduate School of Security Studies and Professor in the Department of International Relations at the National Defense Academy of Japan and an Adjunct Research Fellow at the Japan Institute of International Affairs. His recent works include “China’s Use of Influence in the Indo-Pacific: Patterns and Regional Insights,” Yokosuka: National Defense Academy, 2024 (co-edited).
Notes
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