Prospects for DPRK’s Nuclear Use Scenarios and Deterrence Measures of the US and ROK Alliance

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ABSTRACT

The purpose of this paper is to develop cases for the DPRK’s use of nuclear weapons. As background, firstly, the deterrence and countermeasure strategies of the United States-ROK alliance in the face of the increasingly sophisticated DPRK’s nuclear threat is examined. Then, the DPRK’s nuclear capabilities and nuclear strategy are investigated, and nuclear use cases are presented in detail based on those strategies. The relative priorities and feasibility of the different DPRK nuclear use cases were analyzed using parameters evaluating their military effect, the potential for US nuclear retaliation, and the level of civilian casualties. Among the expected cases, an attack on the ROK Mobile Corps would seem to be the most probable scenario, since the benefits that the DPRK would gain from such an attack would be high. Within that case, there is a danger of nuclear provocation due to the asymmetry between the DPRK’s nuclear possession and ROK’s possession of only conventional forces. The importance of the US extended deterrence policy to deter the DPRK’s nuclear threat is therefore emphasized, and measures to strengthen the credibility of US extended deterrence are also suggested.

KEYWORDS:

• DPRK
• nuclear capabilities
• nuclear strategy
• nuclear use cases
• US-ROK alliance

Disclosure statement

This article reflects the personal opinions of the author, not the official opinions of the government of the Republic of Korea.

Notes

¹ The 8th Party Congress report includes the following messages of tactical weaponization and tactical nuclear weapons. In the second part of the report (“Current achievements”), it states “총결기간 이미 축적된 핵기술이 더욱 고도화되여 핵무기를 소형경량화, 규격화, 전술무기화하고 초대형수소탄개발이 완성되였으며”, for which the English translation is “During the previous congress period, the nuclear technology that had already been accumulated was further advanced, so it was completed that making nuclear weapons smaller and lighter, standardized, and tactical weaponization, and the development of super-large hydrogen bombs.” In the fourth part of the report (“Future plans”), it states “핵기술을 더욱 고도화하는 한편 핵무기의 소형경량화, 전술무기화를 보다 발전시켜 현대전에서 작전임무의 목적과 타격대상에 따라 각이한 수단으로 적용할수 있는 전술핵무기들을 개발하고 초대형핵탄두생산도 지속적으로 밀고나감으로써”, for which the English translation is: “While further advancing nuclear technology, we will further develop miniaturization and tactical weaponization of nuclear weapons to develop tactical nuclear weapons that can be applied in various ways depending on the purpose of operational missions and targets in modern warfare, and continue to push forward the production of super-large nuclear warheads.”.

² Tactical nuclear weapons developed by the DPRK may be “gun-type” weapons using U-235 as the DPRK’s stocks of enriched uranium increase.

³ Several studies have pointed out and are concerned about this possibility. An example is Ham (2021).

⁴ If the DPRK perceives that the credibility of extended deterrence by the United States cannot be guaranteed, it may misjudge that the United States will not guarantee the use of nuclear weapons at a similar level (low yield) to those used by the DPRK on the Korean Peninsula, leading the DPRK to believe that it could use nuclear weapons without being attacked with nuclear weapons in return.

⁵ This type of damage could occur with either ground burst or air burst weapons detonation, though not with high-altitude explosions. Depending on the height of the explosion, an air burst could also cause some fallout. Fallout would create a wider range of contaminated areas than the areas where the detonation would have direct lethal impacts.

⁶ There are many studies and articles describing the potential for the DPRK to use nuclear weapons to create EMPs with high-altitude explosions. These include Pry (2019); Pry (2021).

⁷ It has been suggested that it might be possible for the United States, through satellite surveillance, to identify nuclear missiles as the DPRK brings them out of storage for use. It is questionable, however, whether it is possible to completely distinguish between conventional warheads and nuclear warheads during transport.

⁸ The term “Leaky Umbrella” is used in Anderson and Larsen (2013) and Holdor (2013).

⁹ Similar concerns were expressed in Davis et al. (2016).

¹⁰ Although there is unlikely to be a fundamental solution to strengthening extended deterrence due to a gap in the credibility of the US deterrence policies, the efforts of both countries to reinforce their alliance should continue at a level that each can accept.

¹¹ The addition of these weapons by the United States in the 2018 NPR reflected the concern that the ROK has regarded US extended deterrence. The ROK continues to build its conventional defensive capabilities. Although “nuclear sharing,” referring to US extended deterrence, is an effective approach, it does not really constitute “sharing” of nuclear weapons between the United States and the ROK due to the nature of the US nuclear command and control system. To clarify this relationship in the 2018 NPR, “nuclear sharing” was deleted and replaced by “burden sharing.”

¹² When considering planning/employment as well as deterrence of nuclear weapons, it would be natural for the ROK to actively participate in the nuclear planning/employment program on the Korean Peninsula (which is Korean territory) with the United States, given the ROK/United States alliance. The point here is that the withdrawal of US nuclear weapons from the ROK has raised some doubts in the ROK about US extended deterrence because the lack of the physical presence of nuclear weapons in the ROK appears to further remove decisions about nuclear forces from ROK involvement.

Additional information

Funding

This paper is prepared for Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), a project co-sponsored by Research Center for Nuclear Weapons Abolition, Nagasaki University (RECNA), Asia Pacific Leadership Network for Nuclear Non-Proliferation and Disarmament (APLN) and Nautilus Institute with collaboration of Panel on Peace and Security of Northeast Asia (PSNA). Additional funding is provided by the MacArthur Foundation.

Notes on contributors

Sangkyu Lee

Sangkyu Lee is a Republic of Korea (ROK) army officer and assistant professor at the Korea Military Academy (KMA). His main research focus is the Democratic People’s Republic of Korea’s (DPRK) nuclear threats, including its nuclear capabilities, strategies, and command and control system. Professor Lee holds PhD and MS degrees in Nuclear Engineering from the University of Utah in the United States. He has been an assistant professor in the Department of Physics at KMA since 2019, and from 2017 to 2018 served as the Nuclear Policy Planning Officer at the North Korea Policy Bureau, Ministry of National Defense, Republic of Korea.