Project on Reducing the Risk of
Nuclear Weapons Use in Northeast Asia (NU-NEA)

Possible Nuclear Use Cases in Northeast
Asia: Implications for Reducing Nuclear Risk
Co-sponsored by
The Research Center for Nuclear Weapons Abolition,
Nagasaki University (RECNA)
The Nautilus Institute for Security and Sustainability
The Asia-Pacific Leadership Network for
Nuclear Non-Proliferation and Disarmament (APLN)

with cooperation ofPanel on Peace and Security of Northeast Asia

Additional funding by
the MacArthur Foundation
January 28, 2022

Acknowledgments
This report was prepared by primary author David F. von Hippel, with contributions from NUNEA Project Staff and its Steering Committee: Peter Hayes, Shatabhisha Shetty, Tatsujiro
Suzuki, Fumihiko Yoshida, Michiru Nishida, Eva Lisowski, and Steve Freedkin.
The NU-NEA project is funded by Nagasaki University and the John D. and Catherine T.
MacArthur Foundation.
This report is published simultaneously by RECNA, APLN, and Nautilus Institute. This report ispublished under a 4.0 International Creative Commons License, the terms of which are found here. The
authors may be contacted via email at: nautilus@nautilus.org.
Copyediting by Maureen Jerrett.
Banner image: Sophia Mauro for Nautilus Institute.

Citation:
RECNA-Nagasaki University, Asia Pacific Leadership Network, Nautilus Institute, "Possible Nuclear
Use Cases in Northeast Asia: Implications for Reducing Nuclear Risk," January 28, 2022, at:
RECNA: https://www.recna.nagasaki-u.ac.jp/recna/nu-nea_project2021-2023-eng
APLN: https://apln.network/projects/nuclear-weapon-use-risk-reduction/final-report-year-1
Nautilus Institute: https://nautilus.org/napsnet/napsnet-special-reports/possible-nuclear-use-cases-innortheast-asia-implications-for-reducing-nuclear-risk/

Executive Summary
The bombings of Hiroshima and Nagasaki, Japan, in 1945 remain the only instances in history of
nuclear weapons detonation in a conflict. In the three-quarters-of-a-century since, nuclear
weapons have been “used” primarily as tools of deterrence or coercion—deterring conventionaland nuclear attacks on the nations that possess them and on the allies of those nations andcoercing other nations against mounting attacks. During that interval there have also been many
documented instances, and probably many that remain state secrets, when nuclear weapons use
was narrowly averted, sometimes by the bravery of someone in the nuclear chain of command,and sometimes, just by luck.
Any detonation of nuclear weapons in a conflict today (or in the years to come) risks absolutely
unacceptable consequences, no matter how “limited” the nuclear exchange is or will be. The
premise of this report is that it is crucial to understand a range of possible nuclear weapons “usecases”—the detonation of nuclear weapons at or near the earth’s surface in a conflict situation—
to demonstrate the impacts of such use and to spur the development of policy options that can be
deployed to reduce the potential for nuclear war in the future. The fact that these cases are
posited here does not mean they are likely; it simply means they are plausible. Although some of
the use cases do include only limited use, and in one case, failed use, of nuclear weapons, andlead, ultimately, to a meeting of the minds between nuclear-armed opponents and the eventual
reduction of the risk of nuclear war, none of these use cases are in any way desirable in and ofthemselves, and all possible efforts should be made to avoid any nuclear weapons use. “Let
Nagasaki be the Last!” must therefore be the goal of policymakers in international security.
The nuclear use cases posited in this Report span a range of cases, with a range of ultimate
outcomes. In one case, a nuclear detonation is attempted but is not successful, and the adversarythat is the recipient of the attack exercises sufficient restraint that no counterattack with nuclear
weapons occurs. A variety of cases are provided where conflict involves a nuclear weapons
detonation, in most cases followed by a nuclear counter-attack in which diplomacy results in theexchange being “limited” to a few targets. In some of the cases described it is hard to see how aconflict would result in anything short of global (or near-global) nuclear war.
In the use cases presented, the elements of use cases considered are “Triggering Events and First
Use,” “How the Conflict Evolves,” “Use Case Consequences,” and “Use Case Uncertainties,
Ultimate Outcome, and Policy Lessons.” The use cases also span the continuum from“unintended” use, in which a state or non-state actor, for example, had not planned to use nuclear
weapons but does so due to an accident and/or a misperception of an adversary’s intentions, to“intended” or “deliberate” use, when a party uses nuclear weapons for coercion or to gain
advantage in a planned invasion. The use cases posit more numerous first use options for the
DPRK and the United States as these are the principal antagonists on the Korean Peninsula,which has for many years been a primary, but hardly the only, locus of conflict in Northeast
Asia. There are, however, additional first use cases that could be devised for China, and to an
arguably lesser extent, Russia, and other actors.
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 12

Some of the similarities between use cases include:•

Many of the use cases involve first use in which one adversary misinterprets the actionsof another.

•

Many of the use cases turn on the personality of a leader and how he or she responds to acrisis involving nuclear weapons.

•

Many of the use cases occur when one or more of the adversaries, or at least theleadership of same, are distracted by other issues, including domestic issues and issues
abroad.

•Many of the use cases involve lack of communications, or lack of timely or clear
communication between rivals and, in many cases, between allies, or even between those
responsible for operating the assets of a single military.

•

Many of the cases include key decision points where either escalation or de-escalation ofa conflict is possible, based on the choices (or failures to choose) of military and civilian
leaders at those moments.

•

Many of the cases may involve large uncertainties about the outcome of the nuclear
conflicts. It is difficult to foresee what would happen once a nuclear weapon is used, andnuclear use may escalate to uncontrollable nuclear conflict regardless of what decision
makers want.

Key differences between use cases include:•

Although many use cases use similar delivery systems—dictated in part by the distance
between adversaries as well as their arsenals—some use very different means of moving
nuclear weapons to targets and thus require different sorts of policy approaches to reduce
the threat of nuclear use.

•

The nuclear arsenals that potential adversaries have, at this point, differ substantially inboth quantity and quality, which colors the decisions to use or not use nuclear weapons.

•

The nuclear weapons arsenals of the potential adversaries, and the technologies that canbe used to deliver them, are not static; security challenges a few years from now may be
addressed by very different weapons than are currently used.

•

The adoption, or rejection, of opportunities for stopping conflict through negotiation.
Different approaches to negotiation may produce significantly different outcomes tonuclear conflicts, although the effectiveness of negotiation can also vary widely.

Initial policy lessons from these use cases—to be revised and augmented based on analysis to be
carried out in future years of the NU-NEA project—include:•

The need for continuously trusted and reliable open lines of communications between
adversaries at multiple levels.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

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•To improve mutual trust and encourage transparency and consistency in describing theextent and operation of military alliances.

•

Seek to separate as much as possible the operation of international relations fromdomestic political concerns, particularly (but hardly exclusively) in nations whereleadership changes are frequent.

•Seek to insulate the operations of nuclear weapons from the personal or political vagaries
of national leaders, possibly by strengthening oversight on the use of nuclear weapons.

•

Seek to fully brief leaders, military and otherwise, regarding what is known, what is notknown, and what is possible about the goals, concerns, and emphases of adversaries so as
to allow leaders to better understand and identify, to the extent possible given typically
substantial uncertainties, the ways in which opposing leaders might react in situations ofstress.

•Exercise patience, and adjust expectations for results, in international negotiations,particularly those involving the DPRK.

•

Equip nuclear weapons systems with redundant command and control mechanisms that
help to assure that a nuclear weapon can never be launched without adequate authority
and oversight.

•

Work toward insulating key systems (electric power and communications among them)from high-altitude electromagnetic pulse (HEMP) bursts, and/or develop robust back-up
arrangements designed to keep those systems running.

•

Anticipate that potential breakdowns in communication in the nuclear command andcontrol will occur, whether because of, for example, a HEMP detonation or cyberattack,or because of natural disasters such as earthquakes or severe “solar storms” and assurethat commanders in possession/control of nuclear weapons have clear orders as to what to
do in those instances.

•

Encourage all nuclear weapon states to adopt a “No-first-Use” declaration policy as astep toward substantially reducing the risk of nuclear war. The declared nuclear weapons
states (NWS) in the region should endorse such policies.

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Contents
Acknowledgments........................................................................................................................... 1
Executive Summary ........................................................................................................................ 2
1

2

3

Objectives and Introduction .................................................................................................... 7
1.1

Project objectives and of use case development and analysis ........................................ 7

1.2

Summary of nuclear weapons situation on the Korean Peninsula and in NEA .............. 8

1.3

Summary of project goals, approaches/methods, and organization .............................. 16

1.3.1

Approaches and methods, by project year .............................................................. 16

1.3.2

Project organization ................................................................................................ 17

1.4

Summary of project activities and outputs.................................................................... 17

1.5Road map of this report................................................................................................. 19

Nuclear Weapons Use Cases ................................................................................................ 20
2.1

What Defines a Use Case? ............................................................................................ 20

2.2

Applications of Use Cases ............................................................................................ 21

2.3

Goals in assembling and evaluating a range of use cases ............................................. 22

2.4

Criteria for developing and selecting from use cases ................................................... 22

2.5

Common considerations for use cases (scale of weapons use) ..................................... 24

2.6

Information needed from use cases for future modeling .............................................. 25

Use Cases .............................................................................................................................. 26
3.1

DPRK as First User ....................................................................................................... 39

3.1.1“We’re Still Here”................................................................................................... 39

3.1.2“The Best Defense is a Good Offense”................................................................... 45

3.1.3“Last Option for Survival” ...................................................................................... 52

3.1.4“We’ve Got Them Where We Want Them” ........................................................... 55

3.1.5"Help Not Wanted" ................................................................................................. 57

3.2

United States/ROK as First User .................................................................................. 60

3.2.1"The Best Defense is a Good Defense" .................................................................. 60

3.2.2"US Leadership Hubris" ......................................................................................... 63

3.2.3"Response to DPRK Proliferation" ......................................................................... 67

3.2.4“Tripped at the Finish Line” ................................................................................... 69

3.2.5"A Promise is a Promise" ........................................................................................ 72

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3.3

China as First User ........................................................................................................ 75

3.3.1
3.4

Russia as First User ....................................................................................................... 78

3.4.1“Threats to Russian SSBN Bastions” ..................................................................... 78

3.4.2“Dead Hand Error” ................................................................................................. 80

3.5

Non-Nuclear Weapons States and Non-State Actors as First Users ............................. 83

3.5.1“Broken Promises Leads to Breakout” ................................................................... 83

3.5.2

Nuclear Weapons Use by Terrorists ....................................................................... 87

3.6
4"Not Going Well in Taiwan" .................................................................................. 75

Other Potential Use Cases and “Wild Cards” ............................................................... 92

Summary of Use Case Development and Initial/Provisional Policy Lessons ...................... 93
4.1

Summary of Use Cases ................................................................................................. 94

4.2

Initial Policy Lessons .................................................................................................... 96

4.3

Outstanding and Unresolved Questions ........................................................................ 99

Glossary ...................................................................................................................................... 102
ATTACHMENTS ....................................................................................................................... 107
ATTACHMENT 1: TECHNICAL DEFINITION OF “A KILOTON” AS USED IN
IDENTIFYING THE EXPLOSIVE POWER OF A NUCLEAR DEVICE ........................... 107
ATTACHMENT 2: CONSIDERATIONS WITH RESPECT TO USE CASES—
COMMISSIONED PAPERS .................................................................................................. 110

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1

Objectives and Introduction

The risk of nuclear war—that is, the risk of attacks carried out by detonating nuclear weapons,hereafter “nuclear weapons use”—is now said to be at its highest since the end of Cold War.1
There is growing concern in Northeast Asia that potential conflicts may trigger either planned or
accidental use of nuclear weapons in the region. Even the first use of a nuclear weapon would
likely bring horrific and unacceptable outcomes, and the events following from a first use of
nuclear weapons could easily spin out of control, leading to an “open-ended” outcome with somuch uncertainty that global catastrophic war would be a distinct possibility. The memory of thehorrific loss of life and damage from the nuclear bombings of Hiroshima and Nagasaki in 1945
underscore the near-universal conviction that nuclear weapons must never again be used. At thesame time, nuclear arsenals continue to grow, and nuclear “deterrence” remains a key part ofmilitary plans and geopolitics generally. Abolition of nuclear weapons remains a distant hope. In
the interim, the risk of the use of nuclear weapons must be reduced. “Let Nagasaki be the Last!”
must therefore be the goal of policymakers in international security.2

1.1 Project objectives and of use case development and analysis
The overall objective of the “Reducing the Risk of Nuclear Weapons Use in Northeast Asia”
project is to reduce and minimize the risk that nuclear weapons will be used in the region by
developing better understandings of the processes that could lead to the first use of nuclear
weapons and the potential outcomes of such nuclear weapons use. Improved understandings ofthe potential paths to and impacts of nuclear weapons use will help to inform the development
and implementation of policies designed to reduce the risks of nuclear weapons detonation. Our
objective is to prevent any use of nuclear weapons in the region and, ultimately, to avoid armed
aggression or war.
To understand the risk of nuclear weapons use and to develop policies to lower that risk, theReducing the Risk of Nuclear Weapons Use in Northeast Asia project has as its basic objectives
to address the risk of nuclear use by answering the following questions:
1) Under what conditions might nuclear weapon be used (with or without intention) in
Northeast Asia (NEA) and by whom? How might such first use of nuclear weapons

1

The “Doomsday Clock” of the Bulletin of the Atomic Scientists, which is set closer to “midnight” by the Bulletin’s
Science and Security Board when the Board deems the risks of nuclear war are greater, is as of this writing set at
100 seconds before midnight. See “This is your COVID wake-up call: It is 100 seconds to midnight,
2021 Doomsday Clock Statement,“ January 27, 2021, available at https://thebulletin.org/doomsday-clock/currenttime/2
The words “Let Nagasaki be the Last!” begin the 2015 Nagasaki declaration of the Pugwash Council. See Pugwash
Conferences on Science and World Affairs (2015), “2015 Nagasaki Declaration,” dated November 5, 2015, andavailable as https://pugwash.org/2015/11/05/2015-nagasaki-declaration/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

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escalate to a larger scale of nuclear war? And which states might respond to a firstnuclear use with nuclear weapons use of their own?
2) What are the possible consequences (fatalities, physical damages to key infrastructure,environmental damages, climate impacts, and more) of potential nuclear weapon use in
Northeast Asia?
3) What are the possible measures to reduce the possibility of use of nuclear weapons in theregion? That is, what lessons do analyses of use cases offer for the development anddeployment of policies that will help to avoid nuclear weapons use?
It is Step 1 of this process, the development of nuclear use cases involving, though notnecessarily restricted to the Korean Peninsula, that it the focus of this Report.

1.2 Summary of nuclear weapons situation on the Korean Peninsula and in NEA
Northeast Asia is home to two declared nuclear weapons states and United Nations Security
Council members in the People’s Republic of China (the PRC, or China) and the RussianFederation (Russia); one de-facto nuclear weapons state—the Democratic People’s Republic ofKorea (DPRK)—and two non-nuclear weapons states with large nuclear power programs in the
Republic of Korea and Japan; and Mongolia, which has neither nuclear power nor nuclear
weapons and, although it does have uranium resources, has declared itself a “nuclear weapons
free zone.”3 The definition of Northeast Asia for the purposes of this Report includes Taiwan, as
it is a likely flash point for potential conflict without which any consideration of nuclear use
cases in the region would be incomplete. In addition to these NEA neighbors, an accounting of
the presence of nuclear weapons and nuclear deterrence in the region would be seriously lacking
without the inclusion of the roles of the United States in the region. The United States has anumber of major military bases in the region, including in the ROK, Japan, and, to the south,
Guam. Although US nuclear weapons were removed from the Korean Peninsula itself in 1991,
the United States extends its “nuclear umbrella” over the ROK, Japan, and quite unofficially(although meaningfully) Taiwan.
Sketches of the nuclear weapons capabilities of these states are provided below.
•

China is thought to possess approximately 350 nuclear weapons, with delivery systems
including short and long-range land-based missiles (including intercontinental ballistic
missiles, or ICBMs, that can be fired from fixed or mobile launchers, ballistic missile
submarines, missiles based on ships, and bombers.4 Most or all of these weapons arethought to be strategic nuclear weapons, that is, not developed for tactical or battlefielduse. The expansion of China’s nuclear forces has been underway in recent years,
underscored by recent reports of large-scale development of what are thought to be new

3See, for example, United Nations Platform for Nuclear-Weapon-Free Zones (2020), “Mongolia’s nuclear-weaponfree status”, available as https://www.un.org/nwfz/content/mongolias-nuclear-weapon-free-status.
4
See, for example, Hans M. Kristensen and Matt Korda (2020), “Chinese nuclear forces, 2020”, Bulletin of theAtomic Scientists, Volume 76, 2020 - Issue 6 Pages 443-457, published online: 10 Dec 2020, and available ashttps://www.tandfonline.com/doi/full/10.1080/00963402.2020.1846432.

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8

missile silos for ICBMs in Xinyang and Gansu provinces.5 Starting in 1964, and ending,at least nominally,6 with its signing of the Comprehensive Nuclear Test Ban Treaty(CTBT) in 1996, China is estimated to have conducted forty-seven nuclear tests, of whichtwenty-three were above-ground.7•

Russia possesses over six thousand nuclear weapons, of which 4500 are reported to be
operational8 and can be delivered via a full range of delivery systems including fixed andmobile land-based launchers, sea- and submarine-based missile systems, bombers, andair-launched ballistic missiles. Russia has on the order of 500 non-strategic (tactical)
nuclear weapons in addition to its mostly high-yield strategic warheads.9 Russia has
conducted over 700 nuclear weapons tests.

•

Based on its announcements and weapons demonstrations, the DPRK now has nuclear
weapons and delivery devices designed for different ranges, including continental range.
The DPRK has on many occasions announced its development and possession of nuclear
weapons through its state media outlets and other channels. These announcements
notwithstanding, the actual size of the DPRK’s nuclear weapons arsenal is not knownwith any certainty. Analysts suggest the DPRK may possess sufficient fissile material foron the order of fifty nuclear weapons, although only a fraction of that material may havebeen incorporated into warheads as of 2021.10 The DPRK has conducted six known
nuclear weapons tests between 2006 and 2017.11 The DPRK has been actively developing
and testing missile systems, some of which are thought to be nuclear-capable, extending
from short-range missiles to missiles with potential ICBM capabilities. The DPRK’sdelivery systems are mostly land-based, including a recently-demonstrated capability tofire ballistic missiles from a train, but the DPRK may also be developing the capability tofire ballistic missiles, and potentially nuclear ballistic missiles, from submarines.12

5See, for example, Tong Zhao (2021), “What’s Driving China’s Nuclear Buildup?,” Carnegie Endowment forInternational Peace, dated August 05, 2021, and available as https://carnegieendowment.org/2021/08/05/what-sdriving-china-s-nuclear-buildup-pub-85106
6
Recent low-yield nuclear tests are suspected, but not proven, to have been carried out recently by China. See, forexample, Julian Borger (2020), “China may have conducted low-level nuclear test, US claims,” The Guardian, dated
15 April, 2020, and available as https://www.theguardian.com/world/2020/apr/16/china-may-have-conductedlow-level-nuclear-test-us-report-claims
7
Atomicarchive.com (2021), “China’s Nuclear Tests,” available as https://www.atomicarchive.com/almanac/testsites/prc-testing.html
8See, for example, Hans M. Kristensen and Matt Korda (2021), “Russian nuclear weapons, 2021,”
Bulletin of the Atomic Scientists, Volume 77, 2021, Issue 2, Pages 90-108, published online 18 Mar 2021, andavailable as https://www.tandfonline.com/doi/full/10.1080/00963402.2021.1885869
9Matt Korda (2021), Nuclear Weapons and Delivery Systems that Might be Implicated in Nuclear Use Involving the
Korean Peninsula, paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project,
September 2021 (publication forthcoming).
10
See, for example, 38 North, “Estimating North Korea’s Nuclear Stockpiles: An Interview With Siegfried Hecker,”
dated April 30, 2021, and available as https://www.38north.org/2021/04/estimating-north-koreas-nuclearstockpiles-an-interview-with-siegfried-hecker/
11
Nuclear Threat Initiative (2020), “North Korea,” last updated October 2020, and available ashttps://www.nti.org/learn/countries/north-korea/
12
Korda (2021), ibid.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

9•Japan does not possess nuclear weapons, and as a signatory to the Non-Proliferation
Treaty (NPT), is obliged not to develop them. Japan is, however, covered by the UnitedStates’ “nuclear umbrella,” an arrangement denoting the US’ extended nuclear deterrencewith the intent being the assurance of US protection, with nuclear weapons, if necessary,in the event of a conflict. This arrangement is also designed to prevent the developmentof nuclear weapons by Japan and/or by other states also covered by the US’ extended
nuclear deterrence.13 Although the nuclear umbrella is not a formal legal or treaty
commitment, rather a “political assurance,” it has sufficed thus far, along with nationallaws and moral positions born out of being the only nation in history to have suffered anuclear attack, to keep Japan and other “umbrella” states from developing nuclear
weapons. That said, and as indicated in one of the use cases presented in section 3 of thisReport, Japan certainly does have the technical wherewithal to develop nuclear weapons,
probably in a matter of months, in the admittedly unlikely event that concerns about thereliability of the US nuclear umbrella rise to the level that compels it to do so, which
would be an abrogation of its obligations as a signatory to the Treaty on the NonProliferation of Nuclear Weapons (NPT). Japan has tens of thousands of tonnes of cooled
nuclear fuel at its reactors and other sites around the country, uranium enrichment
facilities (used to produce reactor-grade uranium),14 a full-scale plant (at Rokkasho),albeit with a checkered operating history, for reprocessing of spent fuel (extraction andpurification of plutonium for use in “mixed oxide” reactor fuel), and, most importantly,
ownership of over of 46 tonnes of separated plutonium (Pu), of which 8.9 tonnes are instorage in Japan, with the rest is in Europe (15.4 tonnes in France and 21.8 tonnes in the
United Kingdom).15 The amount of Pu in storage in Japan alone is sufficient to make on
the order of a thousand or more nuclear warheads.16•

The Republic of Korea is also covered by US extended nuclear deterrence, is asignatory of the NPT, and is thus also unlikely for those reasons to develop nuclear
weapons. It also is in possession of on the order of ten thousand tonnes of spent reactor
fuel, but does not possess, as a condition of its nuclear energy agreement with the US,

13

Gregory Kulacki (2021), “The US Doesn’t Need to Worry About Japan (or Any Other Ally) Going Nuclear,” The
Diplomat, dated February 05, 2021, and available as https://thediplomat.com/2021/02/the-us-doesnt-need-toworry-about-japan-or-any-other-ally-going-nuclear/, described the US “nuclear umbrella” as follows: “At the dawnof the nuclear age, to encourage friendly countries to refrain from building nuclear weapons, the United Statespromised to protect them with U.S. nuclear weapons. This arrangement came to be called the nuclear umbrella.
The experts call it extended nuclear deterrence.”
14
The World Nuclear Association (2021), “Japan’s Nuclear Fuel Cycle,” updated January, 2021, and available ashttps://world-nuclear.org/focus/fukushima-daiichi-accident/japan-nuclear-fuel-cycle.aspx
15
Japan Atomic Energy Commission (2021), The Status Report of Plutonium Management in Japan—2020, Office ofAtomic Energy Policy, Cabinet Office, dated July, 9, 2021, and available as
http://www.aec.go.jp/jicst/NC/iinkai/teirei/siryo2021/siryo21/2_haifu.pdf
16
Assumes about eight (8) kg reactor-grade Pu required per weapon. See, for example, Union of Concerned
Scientists (2009), “Weapon Materials Basics,” published July 18, 2009, and available ashttps://www.ucsusa.org/resources/weapon-materials-basics; and V. Fortakov (1998), Nuclear Verification:
What It Is, How It Works, the Assurances It Can Provide,” p. 41-51 in International Atomic Energy Agency, Technicalworkshop on safeguards, verification technologies, and other related experience, 253 p, 11-13 May 1998, available
as https://inis.iaea.org/collection/NCLCollectionStore/_Public/30/050/30050964.pdf?r=1

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10either facilities for uranium enrichment or for spent fuel reprocessing. It has, however,attempted to obtain nuclear weapons and related delivery systems in the 1970s-early
1980s and dabbled in clandestine research on reprocessing and other “dual use”
technologies in the recent past, and it has been suggested that ROK proliferation activity
research has been one of the considerations that led the DPRK’s to begin its pursuit ofnuclear weapons.17 The ROK, like Japan, is highly advanced technologically, and there islittle doubt that it could produce nuclear weapons-capable technologies quite rapidly, inthe unlikely event that it made the decision to do so.
•

Taiwan is in a similar position to the ROK, with thousands of tonnes of spent nuclear
fuel in storage and advanced technologies that could readily be used for “nuclear
breakout” in the (again unlikely, unless international circumstances change markedly)
event the decision was made to pursue nuclear weapons. Like the ROK, it too previously
sought to develop its own nuclear weapons. Though it is not, because it is not officially astate, a signatory to the NPT or related agreements, it has said that it will abide by thoseagreements.18 Taiwan is also, at least tacitly and unofficially, covered by US extended
nuclear deterrence, although the United States’ commitment to defend Taiwan is the
subject of “strategic ambiguity.”19•

The United States, though not a Northeast Asian country, has great influence in theregion, both as the guarantor of security for Japan, the ROK, and (tacitly) Taiwan, and asa major and continuing military presence in the region. The United States had nuclear
weapons deployed on the Korean Peninsula (in the ROK) from 1958 until 1991, when
they were removed.20 The United States also had nuclear weapons stored on Okinawa
from 1954 until 1972. The presence of these weapons on territory that was returned toJapan in the 1960s was covered under a secret agreement between the United States andJapan in which neither state would publicly confirm any introduction of nuclear weapons
into Japan’s territory. The agreement did, however, appear to violate Japan’s “three nonnuclear principles” (promises “not to process, produce, or permit the introduction of
nuclear weapons into Japan”) formalized in 1967.21 The United States continues,

17

Anastasia Barannikova (2021), Korean Peninsula Nuclear Issue: Challenges and Prospects, paper prepared for the
Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, September 2021 (publication forthcoming).
18
Monte Bullard (2005), “Taiwan and Nonproliferation,” the Nuclear Treat Initiative, dated May 1, 2005, andavailable as https://www.nti.org/analysis/articles/taiwan-and-nonproliferation/
19
David Brunnstrom (2021), “U.S. position on Taiwan unchanged despite Biden comment – official,” Reuters, dated
August 20, 2021, and available as https://www.reuters.com/world/asia-pacific/us-position-taiwan-unchangeddespite-biden-comment-official-2021-08-19/. See also Sheryn Lee (2021), Avoiding Nuclear War in the Taiwan
Strait, prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, September 2021. On
a US State Department website, the relationship is described as a “…U.S. commitment to assist Taiwan inmaintaining its defensive capability” (U.S. Relations With Taiwan, Bilateral Relations Fact Sheet,” dated August 18,
2018, and available as https://www.state.gov/u-s-relations-with-taiwan/
20
See, for example, Hans M. Kristensen and Robert S. Norris (2017), “A history of US nuclear weapons in South
Korea,” Bulletin of the Atomic Scientists, Volume 73, 2017 - Issue 6, Pages 349-357, published online: 26 Oct 2017,and available as https://www.tandfonline.com/doi/full/10.1080/00963402.2017.1388656
21
See, for example, Mercedes Trent (2019), “The History of U.S. Decision-making on Nuclear Weapons in Japan,”
Federation of American Scientists, dated August 21, 2019, and available ashttps://fas.org/blogs/security/2019/08/the-history-of-u-s-decision-making-on-nuclear-weapons-in-japan/

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11however, to project nuclear deterrence for the ROK and for the region as a whole fromsubmarines, ships, bombers, and missiles based elsewhere, including on US territory andfrom bases in Japan and elsewhere. The United States has a full range of nuclear missile
technologies, including missiles designed for both tactical and strategic delivery of
nuclear warheads. The United States has all available delivery systems, and like Russia
has thousands of warheads of different types and sizes. The Intermediate-Range Nuclear
Forces (INF) Treaty, signed by the United States and the Soviet Union (USSR) in 1987,“required the United States and the Soviet Union to eliminate and permanently forswear
all of their nuclear and conventional ground-launched ballistic and cruise missiles withranges of 500 to 5,500 kilometers.”22 The United States, however, withdrew from the INF
treaty in 2019, and implied that it might deploy intermediate cruise missiles in the AsiaPacific Region,23 although without nuclear warheads. It would, however, be difficult toverify whether the warheads used on these missiles are conventional or nuclear.
A map of Northeast Asia is presented for reference in Figure 1.24

22

See, for example, Arms Control Association (2019), “The Intermediate-Range Nuclear Forces (INF) Treaty at a
Glance,“ last reviewed August 2019, and available as https://www.armscontrol.org/factsheets/INFtreaty
23
See, for example, Idrees Ali (2019), ”U.S. Defense Secretary says he favors placing missiles in Asia,” Reuters,
dated August 3, 2019, and available as https://www.reuters.com/article/us-usa-asia-inf/u-s-defense-secretarysays-he-favors-placing-missiles-in-asia-idUSKCN1UT098
24
Prepared based on a map downloaded from Google Earth, January 7, 2022. The red circles on the map show, forreference, the approximate distance from the demilitarized zone (DMZ) that divides the Korean Peninsula.

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Figure 1: Map of Northeast Asia
In addition to these state “actors,” it is conceivable that nuclear weapons or nuclear devices, suchas weapons designed to spread radioactivity via a non-nuclear explosion, could be used in an
attack in Northeast Asia by non-state groups, such as terrorist organizations. Attacks on nuclear
energy facilities, including reactors and spent fuel storage facilities in the ROK, Japan, orTaiwan, could also be carried out, and such attacks might have significant consequences fornearby populations, including resulting in plumes of radioactive material capable of causing
acute and chronic health impacts, depending on factors such as distance and dilution.25

25

See, for example, David von Hippel and Peter Hayes (2018), Radiological Risk from Accident or Attack at Nuclear
Energy Facilities in China, NAPSNet Special Reports, February 22, 2018, available as

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In sum, the existing, under-development, and (potentially) nascent nuclear weapons capabilitiesof actors in Northeast Asia make it crucial to find ways to reduce the risk of nuclear weapons use,
as well as of the conflicts that might precipitate nuclear weapons use. These nuclear weapons
capabilities, combined with simmering territorial and other disputes, and, of course, thehttps://nautilus.org/napsnet/napsnet-special-reports/radiological-risk-from-accident-or-attack-at-nuclear-energyfacilities-in-china/; and Peter Hayes (2018), Non-State Terrorism and Inadvertent Nuclear War”, NAPSNet Special
Reports, January 18, 2018, available as https://nautilus.org/napsnet/napsnet-special-reports/non-state-terrorismand-inadvertent-nuclear-war/

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longstanding state of war—albeit restrained for nearly 70 years by an Armistice—on the Korean
Peninsula, make the reduction in the risk of nuclear weapons detonation a key goal for our time.

Nuclear Weapons as Deterrents to Conflict
In the more than 75 years since nuclear weapons were last used in wartime, the main
rationale for nuclear weapons has been in deterring conflicts, both nuclear and otherwise. In
a number of historical cases since World War II, both national leaders and their key security
advisors have seen the existence and positioning of nuclear weapons as having significant
value in deterring conflict. Some nuclear weapons proponents argue that the existence of
nuclear weapons has allowed the world to avoid significant conflicts, including avoiding a“World War III” that might have broken out during the Cold War period.26 Such claims may
have merit, but it is of course difficult to prove the role of nuclear weapons in avoiding wars
that did not occur. Moreover, in many conflicts, states were already deterred by other factors
and nuclear deterrence was either non-existent, at the margin, or in some instances may
have undermined the stabilizing effects of non-nuclear deterrence. Also, states have usednuclear weapons for other purposes—reassurance of allies, third parties, and even their
nuclear arch-enemies on occasion; and for compellence unrelated to deterrence—in waysthat may have inflamed conflicts and increased the risk of war and nuclear proliferation
more than would have otherwise be the case.
This study makes no claims with regard to the putative effects of nuclear weapons,stabilizing or destabilizing.
Rather, it addresses the irreducible risks that once started, a nuclear war is likely to havecatastrophic results, may escalate, and may never end; that the pathways to nuclear war are
manifold and under-appreciated in this region; and the risk of nuclear war are amenable topolicy change at acceptable cost. On the other hand, some historians suggest that sucharguments, that is, that the existence and deployment of nuclear weapons deterred major
wars that would have otherwise occurred, is a “myth,” and, rather, that nuclear wars were
avoided not because of “nuclear deterrence” but rather because of luck or unintended
events.
In short, we neither dispute nor affirm the value of nuclear weapons in deterring military
conflict, rather in this Report we focus on the risks that nuclear weapons pose in theincreasingly perilous nuclear security situation in Northeast Asia. Recognition of these risks
demands a renewed and accelerated efforts to resolve conflicts and to reduce the role ofnuclear weapons in conflict.

26

As just three examples of this literature, see Iain King (2019), “The Future of Deterrence: Keeping Nuclear
Weapons Holstered Was the Easy Part,” The Modern War Institute at West Point, dated June 19, 2020, andavailable as https://mwi.usma.edu/future-deterrence-keeping-nuclear-weapons-holstered-easy-part/; Kenneth
Waltz (1981), “The Spread of Nuclear Weapons: More May Better,” Adelphi Papers, Number 171 (London:

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1.3 Summary of project goals, approaches/methods, and organization
As noted above, the overall objective of the “Reducing the Risk of Nuclear Weapons Use in
Northeast Asia” project is to reduce and minimize the risk that nuclear weapons will be used in
the region. This will be accomplished by developing better understandings of the processes that
could lead to the first use of nuclear weapons, and of the potential outcomes of such nuclear
weapons use, of the consequences of nuclear weapons use, and of the policies that might—or
rather, looking back from a case posited to happen in the future, might have—reduced the risksof nuclear weapons detonation. The cases posited for further analysis are defined to take place
between 2025 and 2030.
1.3.1

Approaches and methods, by project year

The project therefore identifies three basic tasks to meet the above objectives, with each task
being the primary focus of each of the three project years:
1. Development of possible nuclear use case. This first task, to be undertaken in year 1,
and of which this Report reflects interim results, has been to develop multiple cases thatinvolve possible nuclear weapon use in the region, including possible escalation to alarger scale of nuclear war through counterstrikes, with a focus on use cases involving the
Korean Peninsula in a regional and global geo-strategic context, and thus possibly
involving actual weapons use in places other than Korea. The goal has been to provide
enough specificity in the definition of the use cases to sufficiently inform the estimates of
the impacts of those cases that modeling of the cases can moved forward during thesecond year of the project.
2. Simulation of nuclear use cases. This second task, to be undertaken in year 2, will be todevelop computer simulations, including the use of the HYSPLIT tool for estimating the
movement and severity of radioactive fallout,27 and other analysis of the nuclear use
cases assembled during Task 1 and to assess potential consequences of such nuclear use
cases. Task 2 will address a wide range of possible consequences, providing quantitativeand qualitative results of impacts including fatalities, environmental damages, andphysical damages, and will prefigure possible climate impacts of nuclear use, which will
be addressed in year 3.

International Institute for Strategic Studies), available as https://www.mtholyoke.edu/acad/intrel/waltz1.htm; andConstance Baroudos (2015), “Nuclear Weapons Enable Peace,” Lexington Institute, dated May 6, 2015, andavailable as https://www.lexingtoninstitute.org/nuclear-weapons-enable-peace/. Examples of arguments
countering the contention that nuclear weapons have, in effect, secured peace are provided in David P. Barash(2018), “Nuclear deterrence is a myth. And a lethal one at that,” The Guardian, dated January 14, 2018, andavailable as https://www.theguardian.com/world/2018/jan/14/nuclear-deterrence-myth-lethal-david-barash; andin Ward Wilson (2013), Five Myths about Nuclear Weapons, Houghton Mifflin Harcourt, published January 15,
2013.
27
HYSPLIT is a computational model described as a tool to “… simulate the dispersion and trajectory of substancestransported and dispersed through our atmosphere, over local to global scales.” See United States Department ofCommerce National Oceanic and Atmospheric Administration (NOAA, 2022), “HYSPLIT,” available ashttps://www.arl.noaa.gov/hysplit/

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3. Development of policy recommendations to reduce the risk of nuclear war in
Northeast Asia. Based on the results of Task 1 and 2, Task 3 will focus on assessing
current nuclear policies in the region and developing policy measures to reduce the risks
that nuclear weapons will be used in the region.
1.3.2

Project organization

The Research Center for Nuclear Weapons Abolition, Nagasaki University (RECNA), Nautilus
Institute (NI), and the Asia Pacific Leadership Network for Nuclear non-proliferation andDisarmament (APLN), with the cooperation of the Panel on Peace and Security of Northeast
Asia (PSNA), are hosting this project. RECNA, NI, and APLN have set up a Steering Committee
as a project management organization. PSNA will serve as an Advisory Group to the Project, andkey members of PSNA will be involved in each task. A Consultative Group of experts in various
disciplines related to the project has also been assembled to provide input to and review of use
cases, with some Consultative Group members also commissioned to prepare background papers
to inform the development and analysis of nuclear weapons use cases.

1.4 Summary of project activities and outputs
In the first year of the project, PSNA and the NU-NEA collaborating partners convened a virtual
workshop with experts from around the world in October 2021 with the goal of reviewing thepotential limited nuclear weapons use cases in Northeast Asia that are described in this Report.
To prepare for this October meeting, the Project partners brought together a “Consultative
Group” of approximately thirty experts to develop and provide project partners with as much of astart as possible in specifying nuclear use cases. These experts provided advice during an on-line
workshop on July 20, 2021. The Consultative Group experts have been drawn from Northeast
Asia, Australia, the United States, and Europe, and have expertise in global and regional
security, the recent history of the Korean Peninsula and the Taiwan Straits, nuclear weaponssystems of the states in the region, defining and of modeling of nuclear use cases, vulnerabilities
of nuclear reactors to attack, and many other relevant disciplines. This Year 1 Consultative
Group was tasked with brainstorming potential nuclear use cases within parameters specified by
the project partners in order to define a set of cases for broader review and continued definition
and ultimately to serve as the basis for quantitative and qualitative estimates of impacts in project
Year 2.
Some of the members of the Consultative Group were commissioned to prepare background
papers to inform the project as a whole, the use cases developed during the project, and theattendees at the October meeting. For the first project year, eleven papers have beencommissioned and completed. A listing of the authors and titles of these papers is provided inTable 1, and abstracts or summaries of the papers received to date are provided in the
ATTACHMENT 2: CONSIDERATIONS WITH RESPECT TO USE CASES—
COMMISSIONED PAPERS” attachments section at the end of this Report. Citations to these
papers appear throughout this Report, but the ideas provided by the commissioned authors, bothwithin and outside of their papers, have influenced most of the elements of the Report. These
Commissioned Papers have, by the time of publication of this Report, either been publishedalready on the APLN, RECNA, and Nautilus websites, or are shortly to be published on thosewebsites as Special Reports to the project.
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Table 1. Papers Commissioned for Year 1 of Reducing the Risk of Nuclear Weapons Use
in Northeast Asia (NU-NEA) Project.
AuthorTitle and Affiliation

Paper Title

Paul K. DAVIS
and Bruce
BENNETT

Adjunct principal researcher and senior politicalscientist (respectively), RAND Corporation,
professors of the Pardee RAND Graduate
SchoolNuclear-Use Cases for Contemplating
Crisis and Conflict in East Asia

Anastasia
BARANNIKOVA

Research fellow at ADM Nevelskoy Maritime
State University (Vladivostok)

Korean Peninsula Nuclear Issue:
Challenges and Prospects

Ian BOWERS

Associate professor at the Centre for Joint
Operations, Royal Danish Defence College

The Counterforce Dilemma in East-Asia
Pacific
Reducing or Exploiting Risk?

Van JACKSONProfessor of international relations at Victoria
University of Wellington

Varieties of US Nuclear Thought and their
Implications for Northeast Asia

Matt KORDA

Research associate, Nuclear Information
Project, Federation of American Scientists, andassociate researcher to SIPRI (StockholmInternational Peace Research Institute)

Nuclear Weapons and Delivery Systems
that Might be Implicated in Nuclear Use
Involving the Korean Peninsula

Major LEE
Sangkyu

Assistant professor, Korea Military Academy,
Department of Physics and Chemistry(Formerly denuclearization policy officer, North
Korea Nuclear Weapon Policy Division,
Ministry of Defense, Seoul, Republic of Korea)

Prospects for DPRK's Nuclear Use
Scenarios and Deterrence Measures of
the United States and ROK Alliance

Sheryn LEE

Senior lecturer in the Division of Leadership at
the Swedish Defence University

Avoiding Nuclear War in the Taiwan Strait

Eva LISOWSKIMIT Graduate, Master's student at Tokyo
Institute of Technology

Potential Use of Low-yield Nuclear
Weapons in a Korean Context

James IMATRAY

Professor, Cal State University at Chico

U.S. Entry into the Korean War:Origins, Impact, and Lessons

Daryl G.
PRESS

Associate professor of Government, Dartmouth
University

Military/Nuclear Force and Counterforce
Strategies on the Korean PeninsulaDavid WRIGHT

Independent missile engineer, research affiliate
with the Department of Nuclear Science andEngineering at MIT

The Role of Missile Defense in North-East
Asian Nuclear Scenarios

The NU-NEA project will span the Japanese fiscal years 2021 through 2023 (approximately
April 2021- March 2024).
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In the first fiscal year, outputs include development of use cases, as conveyed in this Report,
presentation of use cases to PSNA members and other experts for review, revision, andfinalization of the use cases and of the Use Case Report, and the Commissioned Papers listed
above. Outputs in year 2 will include a Report on the results of analyses of use cases, andadditional Commissioned Papers on topics, yet to be determined, designed to inform use caseanalysis. In year 3 of the project, outputs will include a Report on the implications of use caseanalysis for the design and implementation of policies to reduce the risk of nuclear war taking
place in Northeast Asia, again with Commissioned Papers on topics to be determined as theneeds for policy analysis dictate. In each project year, Commissioned Papers and summary
versions of Project Reports will be published in the Journal for Peace and Nuclear Disarmament(J-PAND).

1.5 Road map of this report
The remainder of this Report is organized as follows:•

Section 2 provides a description of what is meant, in the context of this project by“nuclear use cases,” how they are used, and project goals and criteria for use casedevelopment.

•

Section 3 presents the use cases developed thus far for this project, including cases inwhich first nuclear use is carried out by a range of state and non-state actors.

•

Section 4 presents a summary of the use case results and provides initial thoughts on thepolicy lessons offered by the use cases as developed.

•

Following these main sections of this report, a Glossary, including definitions of terms
and acronyms that appear in use cases is provided, along with ATTACHMENTS that
include a short summary of the surprisingly varied operating definitions of the term
“kiloton” in the context of nuclear weapons explosive power, and abstracts or summariesof the papers commissioned for this project thus far.

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2

Nuclear Weapons Use Cases

2.1 What Defines a Use Case?
For the purposes of this project, a “use case” is defined as starting with the detonation of one ormore nuclear weapons in an attack or counterattack against a military opponent. As such, thisdefinition excludes, the “use” that nuclear weapons have been put to in the more than 75 years
since the Hiroshima and Nagasaki bombings of 1945, which is to provide deterrence of apotential enemy’s attack on a state or its territories, allies, or the military assets of either using
either conventional or nuclear weapons. This definition also therefore excludes the detonation of
nuclear weapons as part of tests that do not involve attacks, and the detonation of nuclear
explosives—so-called “peaceful nuclear explosions”—for purposes such as civil engineering, as
has been discussed in the past, tested in many instances (by the United States and the Soviet
Union) but actually carried out (by the Soviet Union) in only a handful of cases.28
Nuclear use cases as defined in this project follow the general considerations described below(section 2.5) as to when in the near future nuclear use is assumed to occur, involvement of the
Korean Peninsula, and other parameters. In addition, to develop nuclear use cases that will be thebasis for modeling key impacts of nuclear weapons use during Year 2 of the project, the use
cases require specification of attributes for each case that include the following:
1. Who are the possible users of nuclear weapons?
•

Which state uses nuclear weapons first?

2. Why does the nuclear use happen? That is, what combination of events, and what
political, economic, environmental, social and/or military circumstances, induce thedesignated actors to pursue nuclear weapons use? This would include consideration of
triggering events such as (but certainly not limited to) accidental first use, pre-emptive
strikes, or responses to terrorism (including both physical and cyber-attacks).
•

What perceived advantage and/or perceived vulnerability led to the use of nuclear
weapons, and how did the situation arise? That is, what is the “back story” of theconflict that makes it potentially realistic?

3. Which state responds to nuclear first use with nuclear weapons and/or conventional
forces?

28

Tests of peaceful nuclear explosions “spanned 1957-75 in the USA and 1965-89 in the USSR.” These tests will bebanned by the Comprehensive Test Ban Treaty when the latter comes into force. See World Nuclear Organization(2018), “Peaceful Nuclear Explosions,” updated December 2018, and available as https://worldnuclear.org/information-library/non-power-nuclear-applications/industry/peaceful-nuclear-explosions.aspx

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4. What and where are the targets of nuclear weapons in each case, and when does theattack occur? What is the target for the first nuclear strike, including location, timing(what season of the year, and what time of day or night29) and type of detonation?
•

What are the targets for subsequent or retaliatory strikes, including the number ofcounterstrikes and the types of targets (military or civilian) involved?

5. How are the first strikes and subsequent nuclear attacks carried out?
•

What size (yield) and type of weapon (uranium, plutonium, hydrogen) is used ineach case?30•

What delivery and targeting systems are used? Information on these elements
helps to determine how likely weapons are to reach their targets and to cause
collateral damage.

6. How plausible is the nuclear use case, and how significant are its impacts likely to be?
•

In order to pose cases that are of relevance to policymakers, they should bereasonably probable within the universe of all possible nuclear use cases in theregion, and•They should have a large enough potential impact — in terms of human lives lost,
economic damage, political repercussions, and/or environmental damage — tocapture the interest of policymakers.

2.2 Applications of Use Cases
In their paper prepared for this project, Paul K. Davis and Bruce Bennett list the following
applications of use cases:31

29

To model dispersion of radioactive particles from a nuclear use incident, it will be necessary to specify both alocation and approximate timing in order to obtain weather data representative of the time and place of weaponsuse. The same information will be needed to calculate other modeling results, for example, human exposure.
30
The size of the weapon used, along with at what level (ground level or in the atmosphere) it is detonated, are
inputs to determine the size and shape (height above the ground, width, and height of “cap” of the mushroom
cloud resulting from the nuclear explosion, which in turn is an input to the distribution of the sources ofradioactive particles that make up fallout. The location (latitude and longitude) of detonation also may play a rolein the composition of fallout based on the local soil types (or water bodies) and any man-made structures
destroyed in the detonation area.
31
Paul K. Davis and Bruce Wm. Bennett (2021), Nuclear-Use Cases for Contemplating Crisis and Conflict in East
Asia, paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, 9 December,
2021, and available as APLN, RECNA, PSNA, and Nautilus Institute Special Reports at
https://www.apln.network/projects/nuclear-weapon-use-risk-reduction/nuclear-use-cases-for-contemplatingcrisis-and-conflict-on-the-korean-peninsula, https://www.recna.nagasaki-u.ac.jp/recna/topics/29469,
https://www.recna.nagasaki-u.ac.jp/recna/psnanews/29485, and https://nautilus.org/napsnet/napsnet-specialreports/nuclear-use-cases-for-contemplating-crisis-and-conflict-on-the-korean-peninsula/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

21•“Education [of] analysts, scholars, policymakers, military officers, staffs, students•

Communication among scholars and practitioners; with public; in negotiations•

Assessing strategic balances from different perspectives and with different assumptions•

Assessing arms control options by governments and outside groups•

Understanding potential outcomes of nuclear war in terms of relative and absolute
military gains and losses, and more broadly•

Identifying problems and opportunities in avoiding or mitigating nuclear war noting
particular weaknesses of deterrence and ways to improve it•

Planning force planning, operational planning, and crisis planning”

Virtually all of these roles for use cases, with the possible exception of detailed force andoperational planning, factor into the applications for the use cases developed during this project,as all of these applications can be thought of as elements in developing and refining policies
designed to reduce the risk that nuclear weapons use will occur.

2.3 Goals in assembling and evaluating a range of use cases
History is strewn with events that failed to be considered by those responsible for planning. In
some cases, these oversights were because those events had not happened before. In other cases,
the events were simply considered to be “unthinkable” for reasons varying from the events being
thought to be “unlikely” to the foibles of human hubris. As such, the goal in this project has been
to assemble as broad a range of use cases as is practicable. Given the many actors in Northeast
Asia, and the almost limitless number of potential triggers for conflict in the region, there are aliterally unlimited number of use cases that might be produced. Limits on the amount of time andhuman resources that can go into developing, and subsequently, evaluating such use cases meanthat a limited suite of use cases can realistically be assembled and analyzed. Our goals in doing
so have been to assemble a set of use cases that includes all of the potential actors in the use of
nuclear weapons in Northeast Asia in general and involving the Korean Peninsula in particular,that include multiple modes of nuclear weapons use, for example, against different types oftargets, in different types of detonations, and at different levels of yield, and to explore a range oftriggering events. The goal in assembling and, subsequently, analyzing this breadth of use cases
is to be able to identify and test policy solutions resulting in reducing the risk of nuclear war
from a range of different angles in order to find policy solutions that can be used to address—andare “robust” responses to—different ways in which nuclear war might arise.

2.4 Criteria for developing and selecting from use cases
In seeking to address the goals in assembling and evaluating nuclear weapons use cases as
described above, we applied and continue to apply the following criteria in developing andselecting use cases for further analysis. Diversity: The group of cases chosen for further analysis
should show diversity in several respects (although they need not be “normally distributed” inany one sense):

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a. State (or non-state) first using nuclear weaponsb. Nuclear detonation (NUDET) targets
c. Drivers/triggering events for nuclear use
d. Modes of attack and weapons used
e. Potential lessons for policy from cases [although we can’t know this fully before
we do our year 2/year 3 analysis, we can project some key lessons based on initialqualitative consideration of the cases]f.

Loss of control of nuclear weapons, including failure of positive control—theorganization and technological measures that allow commands to use weapons to
be relayed reliably—and loss of negative control, that is, controls that keep
nuclear weapons from being used by mistake

2. Divergence: The group of cases span a range of outcomes with respect to, for example:
a. Spread of nuclear use among statesb. A range of different outcomes of nuclear cases, likely from limited or justavoided first or counterattack detonations to runaway nuclear war
3. Impact of the nuclear weapons use on, for example:
a. Politics in each state, including domestic and international, for both the users of
nuclear weapons and those suffering the direct consequencesb. The physical world—the environment and human infrastructure
c. International relations and traded. Military infrastructure, doctrine, and strategy, both in the near and more distantfuture4. Plausibility—each case should be considered the plausible result of the sequence of
circumstances and triggering events that spawn it. “Plausible” here does not mean thesame as “likely or unlikely,” which is typically a judgement based on a reviewer’s
particular perspective or experience, or “probable,” which in most cases regarding
nuclear weapons use is impossible (or very difficult) to assess. To demonstrateplausibility, the use case should be elaborated in a way that is backed up by arguments orevidence, except in totally unexpected cases, and even in those case there may be
precedents in history. Possible criteria for this might include (but are not limited to):a. Do the actors involved—militaries, states, leaders—have the capacity to carry out
the actions that are posited in the use case?
b. What indications of intentions would be expected in each case before use (orresponse), and is it plausible that with those indications absorbed by other actors,
the NUDET would still take place?

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c. Does the use case include elements that have happened (or almost happened)
before, that is, is there a historical precedent?
d. Is there a path from the global, regional, and national situations in 2021 and thosein the day in 2025 to 2030 that NUDET occurs that one could see happening,probably, again, because something like it has happened before?
e. Is there any consideration of international legal implications by the state or statesusing nuclear weapons under, for example, the Additional Protocol of the Geneva
Convention?
f. Are any reactions by other states in the international community—those not
involved, or not immediately involved, in the conflict—plausible?

2.5 Common considerations for use cases (scale of weapons use)
For the purposes of this project, we define nuclear weapons use cases within the following
parameters and constraints:•

Nuclear weapons use cases are designed to occur in the latter half of this decade—2025–
2030. This places the use far enough into the future that some of the events that might
trigger nuclear weapons use have time to develop, but not so far into the future as to be(A) outside of the realm of near-term concern for current policymakers, or (B) affectedby, for example, the development of disruptive technologies that are not yet on thehorizon.

•

Nuclear weapons are assumed to be used in relation to a Korean conflict, or in a conflictthat might arguably expand to or from the Korean peninsula, either intentionally or
perhaps inadvertently, by one or more of the DPRK, the United States, the People’s
Republic of China, or the Russian Federation.

•

State actors are the primary focus of these nuclear use cases, in large part because a major
goal of the project is to develop policy approaches for application by state actors that
reduce the risk that nuclear weapons will be used, but use of nuclear or other weapons by
non-state actors could serve as a triggering event for a nuclear weapons use case.

•

Nuclear weapons use in the cases considered involves Korean peninsula issues and actors(directly or indirectly) but could involve targets elsewhere.

•

The nuclear weapons and delivery systems considered as candidates for application in theuse cases are similar to those found in current stockpiles, although use of weapons
currently in advanced development, such as hypersonic ballistic missiles, could also be
considered.

•

The overall ultimate extent of the nuclear war in the cases to be developed largely
focuses on cases that at least have the potential to remain limited, and not to escalate to a
global or major regional conflict. We do, however, consider uncertainties associated withthe consequences of nuclear exchange in the region that may escalate to nuclear
exchanges involving other parts of the world. Impacts of these escalated cases, including

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24those outside the Northeast Asian region, will NOT be considered in the simulations of
nuclear weapons impacts to be carried out in the second year of the project. We take thisfocus in part because the modeling of impacts of a substantial regional or global nuclear
war, as we as planning for year 2 of the project, is both very difficult and, to a large
extent, pointless/unnecessary, as it is clear that civilization as we know it would notsurvive such an event, and thus the policy lessons offered by such use cases are generally
likely to be few. Some of the cases presented below, however, do escalate beyond alimited exchange of weapons because we feel that it is implausible that those particularcases will not escalate significantly and the cases appear likely to offer valuable lessons
for policy.

2.6 Information needed from use cases for future modeling
The ultimate goal of this project is to reduce the risk that nuclear war will occur bydemonstrating the ways that it might be triggered and evolve, evaluating the impacts of such
events, and identifying policies that could be pursued to reduce, minimize the risk of, andultimately prevent nuclear weapons use. To achieve these goals, nuclear use cases must be
developed in sufficient specificity that they case be used to inform modeling of nuclear weapons
use.
These considerations therefore affect how use cases are specified under this project. For
example, to model dispersion of radioactive particles it will be necessary to specify both alocation and approximate timing of each use of nuclear weapons to obtain weather data
representative of the time and place of weapons use. The same information will be needed to
calculate other modeling results, for example, human exposure to radioactivity, or direct deathsand damage to infrastructure resulting from nuclear blasts. In addition, the size of the weapons
used, along with at what level (ground level or in the atmosphere) they are detonated, are inputs
to determine the size and shape (height above the ground, width, and height of “cap” of themushroom cloud resulting from the nuclear explosion, which in turn is an input to the
distribution of the sources of radioactive particles that make up fallout. The location (latitude andlongitude) of detonation also may play a role in the composition of fallout based on the local soil
types (or water bodies) affected and any man-made structures destroyed in the detonation area.
These are but some examples of the information that will be extracted—sometimes with theapplication of additional assumptions—from use cases such as those specified below.

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3

Use Cases

Below we present at set of nuclear weapons use cases, which will, as noted above, be further
elaborated and ultimately used to evaluate use case impacts in year 2 of our project and to inform
potential policy initiatives to reduce the risk of a nuclear war in year 3. The cases shown havebeen assembled from a wide variety of inputs. Some were suggested by participants in the July
2021 expert Consultative Group meeting. Some are based on ideas presented in the papers
commissioned for this project, or elsewhere in the literature. All cases have been elaborated
and/or modified in some way by NU-NEA project staff to provide the information needed tomove the use case forward for further analysis in year 2 of the project. As such, these cases
reflect a range of inputs and should not be ascribed to any one person. Also, it should beemphasized that while these cases, as noted above, are designed to be plausible, none of thesecases reflect the views of the authors or anyone else as to how the future is expected or
likely to unfold. Rather, they are, essentially, thought experiments prepared to see what we
can learn from them with regard to how nuclear weapons use can be avoided. This isparticularly because there is little that can be done to effectively prepare for a nuclear attack, andthe consequences of any nuclear attack would be, as demonstrated in Hiroshima and Nagasaki in
1945, unspeakably tragic for the human race and for the planet we all live on. As the computer
controlling the US nuclear arsenal concluded, in the climactic scene of an early threat-of-nuclearexchange-escalation-and-annihilation film concluded about nuclear war, “A strange game. The
only winning move is not to play.”32
In addition, two things about these use cases should be emphasized. First, as noted above, thenumber of unique use cases that could potentially be specified is essentially infinite, given thevast array of parameters and timing that might change from case to case, so we have endeavored
to provide a set of use cases that is limited enough to work with but that span the main set of
possibilities for nuclear weapons use in Northeast Asia. That said, we may well have missed
important cases that should be further studied, and we welcome input on additional cases the
project should consider. Second, the cases below remain subject to revision, and we encourage
reviewers of this document to suggest modifications to the cases to make the cases either moreplausible, given what reviewers know about the situation in the region (and their own points ofview) and/or more useful in terms of the policy lessons that might be derived from them.33
We organized the presentation of use cases below as follows. First, the use cases are divided into
subsections denoting which regional actor is the first user of nuclear weapons in a conflict. The

32

The 1983 (and thus Cold War era) movie in which a NORAD (North American Aerospace Defense Command)
computer intones the quoted phrase after cycling through all possible nuclear US/USSR nuclear exchange scenarios
is “WarGames,” and is described (for example) in Wikipedia (2021), “WarGames,” last updated December 1, 2021,
and available as https://en.wikipedia.org/wiki/WarGames33
In addition, the NU-NEA project team will be further elaborating and possibly modifying these use cases as wedevelop the inputs for the analytical modeling of use case impacts in Year 2 of the project.

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actors we consider are the DPRK, the United States (including the combined conventional forcesof the ROK and the UN Command in the ROK and Japan), China, Russia, and an “Other Actors”
category that may include both states that do not currently have nuclear weapons and potential
non-state actors, such as terrorist groups. We further divide the narrative in each use case into
four parts:
1. Triggering events and first use of nuclear weapons.
2. The evolution of military or other conflicts, including counterattacks and any further
nuclear between combatants, after the first use.
3. The further regional consequences of the use case, including notes on potential
impacts/actions by on other countries and the plausibility and significance of the use case.
4. Thoughts on the uncertainties associated with the use case, how the use case might or
might not lead to situations beyond limited nuclear war, and initial lessons from the usecase for policy.
Within these categories, we reflect on aspects of each use case including:•Who is first to use nuclear weapons—whether a state or non-state actor? Note that wehave, for purposes of this exercise, considered high-altitude nuclear explosions designed
to produce a disrupting electromagnetic pulse (HEMP) to not constitute first use of a
nuclear weapon, but rather a triggering event, because the nuclear explosion itself is not
at or near the earth’s surface, though we recognized that this distinction is somewhat
artificial. As such, “first use” is defined as the detonation of a nuclear weapon on an
adversaries’ territory or to attack its assets as sea. The narratives below are organizedbased on the designation of the first use state (or non-state actor) responding to thetriggering events with a first nuclear use in a conflict.

•

What triggering event caused first use, that is, why did the first user intentionally or
accidentally detonate a weapon (also under 1, above)?

•

What and where are the targets of first use, and when does it happen (included in 1,
above)?

•

Which State responds to the first use? This designation is included in (2), above.

•

What and where are targets, and when does the response (counterattack use) of nuclear
weapons happen (part of 2, above)?

•

How are the first use and counterattacks carried out (parts of 1 and 2, above)?

•

What is the plausibility and significance of the use case (part of 3, above)?

•

What do the other nuclear actors—those not directly, or at least immediately—involvedin the conflict—do, and why (parts of 2 and 3, above)?

•

How is the war brought to an end while keeping the nuclear exchange limited, if indeed
the war is contained to a regional and limited conflict (parts of 3 and 4, above)?

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As such, there are many different ways that a conflict involving the use of nuclear weapons inNortheast Asia (or elsewhere) could be triggered and evolve. A vast range of possible events,
ranging from immediate attacks on territory (with conventional weapons) to perceived politicalslights to the need to maintain domestic political leverage could serve as triggers for nuclear firstuse. Further, these use cases are not predictions of what will happen, rather, they illustrate what
could happen. These illustrations are made with the full understanding that any conflict,
especially nuclear conflicts, could proceed along any number of escalatory pathways, as well as apossibly smaller number of de-escalatory pathways.
Nuclear first use by a nation or non-state actor could fall along a range of uses ranging from“unintended,” where nuclear use was not the initial intent of the first party to use nuclear
weapons, but the result, for example, of a misperception of the threats posed by an adversary orof the intentions of an adversary, to “intended” or “deliberate” use, in which an actor with anunderstanding of the threats it faces seeks to gain military or other advantage over an opponent
by using nuclear weapons. The accidental use of nuclear weapons, in which a technical orcommand-and-control failure or mistake, for example, results in nuclear first use, is arguably a
special case of “unintended” nuclear use and could occur during either peacetime or as tensions
rise toward wartime.34
With the exception of purely accidental nuclear weapons use, every use of nuclear weapons infact represents a decision by either a human or a machine to launch, drop, or otherwise deploy
and detonate a nuclear bomb. As such, the distinction between “unintended” and “intended” rests
more on how the decision to use nuclear weapons came about and thus is subjective and spans arange of different circumstances. For example, Davis and Bennett list “unintended escalation in
conflict (matters getting out of hand)” as potentially including instances of•“Operational failures; necessity•

Pressures of “chicken” game35•

Command and control events•

Accidents•

Consequences of artificial intelligence”

Unintended nuclear first use, and unintended escalation of nuclear war once first use has
occurred, are perhaps the class of nuclear use least well-understood by policymakers, and thus
most important to illustrate and to devise policies to address. In addition to the categories offered

34

The typologies of accidental, unintended, and intended use are described in section 2 and Figure 2 of Davis andBennet (2021), ibid, as prepared for the NU-NEA project.
35
A game of “chicken” occurs when two adversaries, neither of which actually wants to enter a conflict, approacheach other as if intending a conflict, hoping and assuming that the other will back down (or “turn chicken”), andthus the conflict will be avoided. A classic use of this vernacular is when two cars speed at each other head on,each assuming the other will swerve at the last minute, but the term is equally applicable to other forms ofconflict.

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by Davis and Bennet, as described above, the prospects for inadvertent nuclear use might beexacerbated by:•

Confusion on the part of one or both adversaries as to the military tactics of the other,perhaps enhanced by fake mobilizations designed to confuse the enemy, which brings anoverreaction in the form of nuclear use.

•

The rapidly growing capabilities of new weapons systems (for example, superhypersonic or space-based weapons, or advanced missile defense systems), and, perhaps
as importantly, adversaries’ fears (justified or not, and enhanced by lack of robust
intelligence) about the advanced capabilities of and advantages conveyed by thosesystems, which could trap a state into believing that a first nuclear strike is necessary toensure its survival.

Figure 2 illustrates a small sampling of triggering events from the use case narratives below andcharts the possible flow of actions resulting from those events through the continuum of
unintended to intended nuclear use, and through the evolution of conflict to the ultimate
consequences as conflicts involving nuclear use play out. For each of the use cases described,
below, we also indicate where, in our view, the first use described in a use case appears on thecontinuum from unintended to intended, although that assessment is, as indicated above,necessarily rather subjective.

Figure 2. Triggering Events and the Genesis of Nuclear Use Cases

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Table 2 provides an overview of the key elements of the use cases presented in this report, and of
how they are related. Details of each use case are provided in the sub-sections below.

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Table 2: Summary of Use Cases Considered
Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences“We're Still Here”
Variant 1

Frustrated by lack of progress innegotiations, DPRK
demonstrates a nuclear weapon
on a low-value, non-military
ROK target
As above, but DPRK attack notcarried out due to malfunction
or timely, successful negotiation

US/UN Commandconventional attack on DPRK
forces near DMZ, US nuclear
attack on nuclear weapons
targets in DPRKUS/UN Command develop
counterattack plan, but do not
implement because of
successful diplomacy
United States uses nuclear
and conventional (with ROK)
weapons on DPRK military andnuclear targets, in part at
insistence of ROK and Japan

High-level US mission
reassures China andRussia, engagement keeps
exchange limited, leads todiplomacy, DPRK opening
China and Russia support
DPRK engagement withinternational community,
diplomacy re-starts
Scale of US counterattack
leads DPRK to begin
conventional war on ROK,
nuclear attacks on UnitedStates and Japan. UnitedStates attacks DPRK
troops with low-yieldweapons
Remaining DPRK
leadership offers terms forceasing military conflictwith international accessto and control over DPRK’s
nuclear weapons in
exchange for “MarshallPlan” for the DPRK
China and Russia stay outof war, but demand say ingoverning DPRK, maybe
through UNSC

“We're Still Here”
Variant 2“We're Still Here”
Variant 3

As in Variant 1, but DPRK
attacks a US naval battle group
offshore of the ROK with anuclear missile fired from DPRK
territory“The Best Defense isa Good Offense”
Variant 1

Changes in United States andROK behavior leave DPRK
leadership convinced that an
attack is imminent, and it
launches what is effectively apreemptive strike on UnitedStates and ROK bases
As above, but with fraying of
US/ROK Alliance“The Best Defense isa Good Offense”
Variant 2

US responds withconventional attacks on
military installations, nuclear
weapons on ICBMs and othernuclear sites and on
Pyongyang command bunker
As above, with US nuclear
attack depending on analysis
of DPRK ICBM capability at thetime

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Uncertainties, Ultimate Outcome,
Policy Lessons
Would US/ROK be able to refrainfrom attacking DPRK leadership?
Close call leads to renewed efforts
at arms control
Lessons: Need to take stock of DPRK
intentions before firing back, beready to deploy high-level
delegations to DPRK and China
Would Russia and China be willingto stay out of the war?
Would the Europe and others in theinternational community be able tomediate a crisis of this magnitude?

DPRK nuclear mines on DMZ mightleave Peninsula divided and badly
damagedDefeated DPRK leadership could
inflict pain to ROK civilian
populations, leaving Korea
uninhabitable
Lessons: Importance of leadership,
US attention, understanding
between allies

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences“The Best Defense isa Good Offense”
Variant 3

As in Variant 1, but withtriggering events including
additional DPRK challenges on
the domestic front, and withDPRK first use in the form of acovert attack on an ROK nuclear
power plant to cause chaos in
the ROK

United States/ROK leadersconclude broader DPRK attack
is imminent, ROK/US troops
needed in ROK, so attack DPRK
troops near DMZ, DPRK
leadership with air
bombardment, then nuclear
weapons“Last Option for
Survival” Variant 1

United States/ROK responds tosocial unrest in DPRK with troop
incursion, DPRK responds with
nuclear attack on ROK

US/UN Command
counterattack on nuclear
weapons and other militarysites in DPRK

“Last Option for
Survival” Variant 2

Perceived or actual DPRK
provocation spurs US/ROK
conventional attack on DPRK
leadership, induces DPRK
nuclear use on ROKDPRK takes advantage of slowmoving talks to invade ROK,
nuclear attack on US bases in
ROK, Okinawa

As above, but could include
attack on DPRK leadership in
Pyongyang if US casualties
substantial

With its remaining
arsenal, the DPRK uses
conventional artillery
and/or nuclear weapons
on Seoul area, uses ICBMs
on United States if
operable
Russia and China stay outof war, may respond to
overflight of missiles,
planesChina and Russia mass
troops at DPRK border,
with some incursion by
China, but no nuclear
response
Attack on Pyongyang
causes China to at least
threaten United Stateswith ICBMs

ROK asks United States to use
nuclear weapons on DPRK
nuclear facilities, troop
concentration, leadershipbunkers

China, Russia go on highalert, Japan comes into
conflict, humanitariancrisis at DPRK/China
border

As DPRK leadership loses
control of its Northern areas
due to bad economy anddisasters/crop failures, Chinese
forces enter to stabilize, andfearing being overrun, DPRK
launches nuclear attack on
China

China launches counterattacks
aimed at DPRK weaponssystems, including with
nuclear missiles on deeply
buried targets

US/ROK and Russian
troops go on alert, but do
not move into DPRK while
China is there, UnitedStates seeks treaty on
northern Korean
peninsula governancewith China, Russia“We’ve Got Them
Where We Want
Them”

“Help Not Wanted”

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Uncertainties, Ultimate Outcome,
Policy Lessons
Additional to the above, lessons
related to reactor security,
provision of backup power forreactors, military, civilians that is
separable from the main grid

May not be probable that
USFK/ROK refrain from attacking
DPRK leadershipWill China be compelled to protect
DPRK?
Lessons: Monitor conditions in
DPRK, offer humanitarian support(international community)

Would DPRK attack whilenegotiations underway? Would
DPRK discount US counterattack
possibility? Could US counterattacks
be mistaken for attacks on China or
Russia?
Would DPRK fear China enough toattack with nuclear weapons?
Would US/ROK troops come to theaid of northern DPRK rebels?
Would Chinese nuclear strikes be
mistaken by United States/Japan?

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences“The Best Defense isa Good Defense”

A ground war starts across theDMZ, and the United States,
distracted by conflicts
elsewhere, fears losing, mounts
conventional (PGM) and nuclear
strikes on DPRK weaponssystems

Fearing an attack on its
leadership, the DPRK launches
a nuclear attack on a US basein the ROK and/or
Okinawa/Guam“US Leadership
Hubris”

Overconfident US president isconvinced that DPRK nuclear
weapons can be destroyed
without counterattack, so
attacks DPRK nuclear weaponssystems

DPRK uses remaining nuclear
weapons, counterattacks
ROK/Japan, possibly by landor sea, to cause major damage
and sue for peace
Possible DPRK attack on a
Japanese reactor to cause
chaos, induce truce

As in other cases above,
China/Russia are eager to
see the United States
weakened but do notwant to enter conflictthemselves, accept US
assurance that conflict
limited to DPRK, future
Korea governance deal
China attacks withconventional weapons tokeep US/ROK south of
DMZ. If DPRK leadership
attacked, China might
attack United States with
nuclear weapons“Response to DPRK
Proliferation”

Proliferation of DPRK nuclear
technologies leads to NUDET
elsewhere, United Statesblames DPRK and attacks DPRK
nuclear infrastructure

DPRK assumes attack on its
leadership imminent, strikes
US bases in ROK, other military
targets, and possibly US
targets if ICBMs advanced
enough and survive attack

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If US attack seem as“unprovoked”, Chinamight come to DPRK aid,
but probably withconventional forces
designed to contain
US/ROK on peninsula

33

Uncertainties, Ultimate Outcome,
Policy Lessons
Could US PGM weapons be
deployed in time?
Would the particular US president
in power at the time use nuclear
weapons first?

Lack of communication by US/ROKwith China/Russia might cause themto use nuclear weapons, trending
toward global conflictLessons: Maintain secure
procedures for war authorizationthat include those outside ofleader’s inner circle; consult withboth allies and potential adversaries
Would ROK condone attack on
DPRK?
Could nuclear forensics lead theUnited States to conclude that DPRK
was responsible for original attack?

Use Case Title“Tripped at theFinish Line”“A Promise is a
Promise” Variant 1“A Promise is a
Promise” Variant 2“A Promise is a
Promise” Variant 3“Not Going Well in
Taiwan”

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Engagement and diplomacy
with the DPRK going well, but
tripped up by change of US
leadership or unforeseen event,
US miscalculation of DPRK
reaction leads United States toattack DPRK nuclear missiles
with PGM and nuclear missiles
After worsening relations withJapan, DPRK launches HEMP
over Tokyo, Japan demands
United States respond with
nuclear attack targeting DPRK
leadership to remove possibilityof counterattack
As above, but ROK is focus of
DPRK HEMPAs in Variant 1, but DPRK
delivers chemical and/or
biological weapons to JapanDPRK conventional
bombardment of Seoul, uses
remaining nuclear weapons
on US bases in region, leading
to full-scale war on the
Peninsula

China and Russia mass
troops at border but stayout of conflict
Japan may become
involved if DPRK attacks
OkinawaWith initial US attack on its
leadership unsuccessful, DPRK
attacks Japan or ROK
populations with nuclear
weapons so as to cause pain,
possibly also using ICBMs on
US territory
US renews attack onleadership with larger,
penetrating weapons

Original DPRK HEMP
attack allows China toconsider US nuclear attack“provoked”
China (and Russia) go on
alert, but do not directlyintervene

Pro-independence governmentin Taiwan, trouble at homeleads China to attack Taiwan,
which is aided by US, but war
goes poorly, so China launches
nuclear attacks on US bases

US attacks Chinese militarysites threatening Taiwan withconventional weapons, attacks
hardened nuclear sites in
China (such as ICBM bases)
with nuclear weapons

Russia may stay out of
conflict, but China likely
counterattacks
United States might ask
NATO to come to its aid,
involving Europe
War may go global

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Uncertainties, Ultimate Outcome,
Policy Lessons
How would DPRK respond to lategame change in US diplomacy?
Would China join if fallout damaged
NE China?
Would United States correctly
identify DPRK brinksmanship andseek to reduce tensions?
Could US attack modes (missiles
from bombers, submarines, ships)
be mistaken by China, Russia, forattacks on them?
Major refugee crisis in the region
likely (ROK and DPRK)
Would Japan or ROK consider HEMP
vs. chemical/biological attacks
sufficiently different as to change
whether they ask for US use of
nuclear?
Lessons: Build HEMP-resilient
infrastructure, discuss with allies
what kinds of attacks require
nuclear response, work to avoid
DPRK conditions that would trigger
attackUnclear with the DPRK would do as
it would likely be surrounded by
fallout, but its survival (as witheveryone else) would be in jeopardy

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences“Threats to Russian
SSBN Bastions”

Higher tensions over territorial
disputes put Russian submarine
corps on maximum alert,
increased tempos, leads to a
sub mistaking exercise or
missile test for an attack, andlaunches nuclear missiles on US
base on Okinawa
At a time of high tensions
between Russia and the West,
communications interruptions
caused by a severe solar storm
puts some Russian early
warning radars offline, leads
automated nuclear launchsystem to mistake ROK spacelaunch for nuclear attack on
Russian bases, leading tolaunches on several US bases in
ROKNew, hawkish leadership andloss of faith in US umbrella
leads Japan to develop nuclear
weapons and use them in
response to DPRK provocations
on DPRK missile and nuclear
infrastructure
For similar reasons to theabove, the ROK develops
nuclear weapons, uses low-yield
warheads to strike at DPRK
leadership

United States, encouraged by
Japan, attacks Russian PacificFleet headquarters and otherRussian bases in the East
Russia attacks US Bases in
ROK, elsewhere

Absent extraordinary andtimely communications,
nuclear war expands to
ICBM launch by both
United States and Russia
on each other’s territory

United States nearlycounterattacks Russia with
nuclear weapons, but ispersuaded not to by feverish
diplomacy both by parties
inside the US and by Russian
officials and diplomats,Russian military concessions,and Russian offers ofcompensation payment to
ROKArms control talks are
reinvigorated, as are
security talks with theDPRKDPRK economic reform
initiated, Russian politicaland military reform begins

DPRK replies with nuclear
missile attack on Japanese
infrastructure or withsmuggled-in warhead to Japan
if the DPRK’s missile
infrastructure isn’t operable

Attack fractures
ROK/Japan relationship,
United States caught in
middleChina intervenes to slow
flow of DPRK refugees
with Chinese troops in
DPRK
ROK takes lead in
rebuilding the Korean
peninsula if not too badly
damaged“Dead Hand Error”“Broken Promises
Leads to Breakout”
Variant 1“Broken Promises
Leads to Breakout”
Variant 2

As above, but with attacks
focused on ROK infrastructure

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Uncertainties, Ultimate Outcome,
Policy Lessons
What standing orders would
Russian Federation (RF) submarine
commanders revert to in times ofcrisis?
Lessons: Raise awarenessCommunications among militaries
about interpretation of perceived
actions
Could a solar storm really affectRussian systems sufficiently tocause error? Could a US president
be convinced to refrain from acounterattack?
Lessons: Use extreme caution inusing artificial intelligence in nuclear
launch systems and improve
nuclear-related communications
between nuclear weapons states

ROK breakout also possible undersimilar conditions
Lessons: Unwise to think that entire
DPRK nuclear arsenal can be
destroyed by a targeted attack
Also may be unwise to expect DPRK
population will embrace ROK as
victorUse Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Terrorist Nuclear
Weapons use
Potential Variant 1

Domestic or international
terrorist organization detonates
warhead in Tokyo—9/11-type
event

Terrorist group claims
responsibility, but evidence
points to DPRK proliferation,
United States attacks DPRK
nuclear sites as in “Promise isa Promise,” at Japan’s request

Nuclear Weapons
use by Terrorists,
Potential Variant 2

Domestic terrorist organization
detonates warhead in Chinese
city

Nuclear Weapons
use by Terrorists,
Potential Variant 3

Cyberwarriors attack nuclear
command-control, launches
nuclear missile from China,
Russia, or United States

China attacks ethnic enclaves
within China, possibly with
nuclear weapons, mightassume United States wasbehind attack and launch at a
US carrier group sailing in theregionVarying evolution dependingon when launch is detected,
whether hacked nation warns
targets, whether targetednation assumes attack to havebeen launched on purpose bynation owning missiles

Renewed attention on
nonproliferation andantiterrorist initiatives
If DPRK blamed, series ofnuclear exchanges UnitedStates to DPRK, DPRK toregion and/or to UnitedStatesChina could obtainsympathy frominternational community,
depending on whether it
decides upon harshcollective punishment

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If attack was assumed
deliberate by targetednation(s), result is
probably an escalating
series of exchanges
Other paths of evolution
yield frantic diplomacy,
more attention on
safeguards, disarmament

36

Uncertainties, Ultimate Outcome,
Policy Lessons
Would terrorist group beintercepted before detonation ofdevice? If so, more emphasis on
non-proliferation efforts, disruptionof nuclear black market worldwide
Would domestic terrorists in China
have organization, skills, money tocarry out such an attack?
Would Chinese punishment of
ethnic groups spur Westerncountries to intervene on Chinese
soil or pursue economic andpolitical sanctions? Or lead instead
to a joint response by the great
powers?
Policy lessons include:
Intensify work on nonproliferation
Improve international nuclear
materials control
Establish or strengthen hotlines toallow immediate reporting of
hacked or accidental nuclear
launches to targeted states

Figure 3 provides a representation of two particular elements of each of the use cases described
below, namely, the degree to which attacks qualify as intentional or unintentional (vertical axis),
and whether nuclear weapons use focuses on urban or limited civilian or limited or large military
targets (horizontal axis). Each use case is marked with its title and with the flag of the nuclear
weapons state that is the first user. For the few use cases where the first user is not now a nuclear
weapons state or is a non-state actor, colors but not flags are used (orange for terrorist
organizations, grey for non-nuclear-weapons states). The groupings of these use cases provide
indications of which types of nuclear use appear to be of particular concern, and thus requireparticular attention to develop policies to avoid such use cases.

Figure 3. Plot of Use Cases versus Intent and Type of Target

Each of the use case descriptions below chart the evolution of the case from triggering event
through first use, responses to first use, and further evolution of the conflict. Each elaborates on
the summaries included in Table 2 and touches on key uncertainties in how the use case mightevolve, potential ultimate outcomes of the case (in the range from the rapid declaration ofceasefire and ultimately peace between the adversaries in the conflict to, in effect, global nuclearwar), and initial policy lessons of the cases.
Figure 4 provides an example of how the evolution of a use case might be charted as a flow
diagram. The case shown is one of the DPRK first use cases described below. One element thisfigure underscores is that nuclear weapons use may be the result of triggering events, but that
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37how the holder of nuclear weapons responds to those events (paths taken versus paths not taken)
makes considerable differences in the use case outcomes.

Figure 4. Example of Use Case Evolution

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3.1 DPRK as First User
For several of the actors with concerns about security in Northeast Asia—in particular, the ROK,Japan, and the United States, the DPRK is perceived as key threat. Its array of conventionalarmaments not far from the DMZ, coupled with its growing nuclear arsenal, continue to be aconcern. That said, a number of authors view the DPRK being the first to use nuclear weapons as
highly unlikely, given that it is understood that DPRK military and civilian (to the extent thatthey are separable) leaders realize that the DPRK faces at close range a much stronger, nucleararmed adversary (the United States, together with the conventional forces of the ROK and the
UN Command), which is much of the reason why the DPRK has developed nuclear weapons in
the first place.36 Many experts in the field evaluate the DPRK’s actions over the decades as
indicating that it is a rational actor simply responding to the circumstances in which it finds
itself. Still, there are a number of potential situations in which the DPRK might conceivably feelforced into being a first user of nuclear weapons. Five such cases, and variants of several ofthem, are presented below.37 Four of these cases involve conflicts between the DPRK and theUnited States/ROK and/or Japan, and one between the DPRK and China.38
3.1.1“We’re Still Here”

In the three “We’re Still Here” variants described below, the DPRK undertakes what can bethought of as a “demonstration” nuclear attack for the main purpose of driving the UnitedStates/ROK and the international community to the bargaining table. In assuming that ademonstration attack will spur the United States into a diplomatic process, the DPRK may bebanking on the belief (which is probably not wrong) that US actions can be more easily
influenced by public opinion than those of other countries, and that the United States could
therefore be pressured into a deal if the DPRK’s attack were limited. As such, these first nuclear
uses can be labeled as “intentional,” along the continuum of intentionality presented above, but
are not intended by the DPRK to induce broader nuclear conflict. The first two variants, both ofwhich might be described as “optimistic” among the suite of use cases involving the DPRK, varywith respect to success of attack and to the US (and UN Command for conventional weapons)
response. The third variant, an attack on a US Navy battle group at sea, draws a more rapid andcomprehensive response, thus rendering timely diplomacy unlikely. In each case, the DPRK
36

See, for example, Anastasia Barannikova (2021), Korean Peninsula Nuclear Issue: Challenges and Prospects,
paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, September 2021
(publication forthcoming).
37
Several of the cases of DPRK first use of nuclear weapons described below draw in part on cases described in Lee
Sangkyu (2021), Prospects for DPRK's Nuclear Use Scenarios and Deterrence Measures of the US and ROK Alliance,
paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, September 2021
(publication forthcoming).
38
Although many (though hardly all) of the cases in which the DPRK is the first user of nuclear weapons involve
attacks on ROK territory, a fair point has been made that the DPRK has greater incentives to attack areas outside
the Korean Peninsula. These incentives include, for example, maintenance of ROK infrastructure (for example, foruse in a reunified Korea under DPRK rule) and reduced risk of radioactive fallout drifting North. The DPRK would
need to weigh these incentives against, for example, the risk that attacks on US bases in the ROK with only
conventional weapons will leave too much of the US on-peninsula war-fighting capabilities intact.

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attacks are attempts at coercion by the DPRK, and thus fall at the “intentional” or “deliberate”
end of the spectrum of attacks indicated in Figure 2 and Figure 3. In each case, DPRK use of
nuclear weapons would probably be preceded by at least veiled or non-specific threats of nuclear
weapons use, perhaps not so different than has occurred in the past.39
Triggering Events and First Use
Variant 1: Frustrated by lack of attention from the international community in general and theUnited States in particular, the DPRK “ups the ante” and “demonstrates” a nuclear weapon on a
not-particularly-valuable target in the ROK. The attack consists of the DPRK firing a short-range
missile with a low-yield warhead at a low-value target, perhaps one of the islands south of theNorthern Limit line on the West Coast, or perhaps a small coastal community not far south of the
DMZ on the East Coast. The target community could be one that hosts a Coast Guard or similarsmall military facility. The DPRK’s attack is designed not to cause significant damage or
massive casualties and is possibly detonated at a relatively high altitude to further reduce damage
and the possibility of damage in DPRK territory.40
The neglect the DPRK perceives may have been brought about by a combination of events
distracting US leadership, which, in combination with domestic problems within the DPRK,
goad the DPRK into acting. Examples of potential distractions for US leadership include, forexample, a hotly-contested presidential election in which fraud is alleged, and/or evidence that
Afghanistan has once more become a terrorist hotbed, and/or a humanitarian crisis in
Afghanistan or elsewhere, and/or a resurgence in COVID-19, and/or “culture wars” in the UnitedStates coming to a breaking point, all of which either have analogs in recent history or are readily
imagined based on what is happening in the United States today. Some of the domestic problems
that could contribute to increasing the impatience of DPRK leadership with the lack of attention
it is getting from the international community could include a COVID-19 outbreak in the DPRK,
increasingly difficult economic conditions due to UNSC sanctions (coupled with more effective
enforcement of same) and/or natural disasters, and a population growing, perhaps quietly,
restive, and with more visibility into conditions in the ROK and the rest of the world. It is
possible that DPRK forces might fake a small attack on DPRK territory, making it look like an
ROK attack, in order to justify its own attack to its own people and/or international observers.
Although this type of use case would nominally violate the DPRK’s stated policy of no firstuse,41 because the use is of low yield and focused on a “low-value” target, and especially if the39

As in, for example, 2020, when the DPRK “threatened to employ nuclear weapons against the United States,
saying such drastic action represents the only remaining way to counter the threat it perceives from the Trumpadministration.” Paul D. Shinkman (2020), “North Korea Threatens U.S.: Nuclear Attack ‘The Only Option Left’”, US
News and World Report, dated, June 26, 2020, and available as https://www.usnews.com/news/worldreport/articles/2020-06-26/north-korea-threatens-us-with-nuclear-attack
40
Parts of this case are similar to elements in one of the cases proposed by Paul Davis and Bruce Bennett (2021,
ibid), including the use of an "innocuous target." Triggering event and drivers for DPRK first use are along the linesof those proposed by Van Jackson (2021), in Reducing or Exploiting Risk? Varieties of US Nuclear Thought and Their
Implications for Northeast Asia, paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast
Asia project, September 2021 (publication forthcoming).
41
See, for example, Richard Smart (2016), “North Korea will not use nuclear weapons first, says Kim Jong-un,” The
Guardian, dated 8 May 2016, and available as https://www.theguardian.com/world/2016/may/08/north-korea-

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use comes with some advanced warning (no more than hours, for example), the DPRK might see
it not as “crossing the nuclear threshold” but rather only a small step beyond the combination of
missile tests, nuclear weapons tests, and small-scale military provocations that have been part ofits repertoire for a number of years.
The DPRK’s first use might take place in the late winter, coinciding with a period whenprevailing winds are north to south, and thus (on average) would tend to blow radioactivity to thesouth and away from DPRK territory. Late winter also corresponds with a period when foodsupplies in the DPRK are likely to be at a low point, and electricity supplies are likewise likely to
be more sporadic than usual because rivers and thus hydroelectric output are low.
Variant 2: The drivers/triggering events and activities for Variant 2 of this use case are the sameas those of Variant 1, but in Variant 2 either (a) the missile’s warhead does not function (either
by actual malfunction or by DPRK design), leaving the target community with some damage but
few casualties; (b) the DPRK warns of the attack an hour in advance, but does not show where
the missile is (or deploys multiple decoys leaving US/ROK forces too unsure of where themissile is to fire on any locations), leaving time for residents to get out, but the attack continues
and causes damage to infrastructure; or (c) the DPRK warns of the attack and demonstrates
readiness to move ahead with it, perhaps using a civilian human shield around the missile to keep
US/ROK forces from attacking it, but allows a high-level negotiator from the US/ROK
alliance—perhaps the sitting president(s) or a respected interlocutor from the past, to “talk themout” of firing with the promise of prompt and fruitful negotiations on a ceasefire/peace-andcompensation deal.
Variant 3: In this third variant, the DPRK chooses an offshore target, for example, a US Navy
carrier battle group. Here, once again, the drivers and triggering events/activities that induce the
DPRK to first nuclear use are the same as those in Variant 1, but the DPRK fires a nuclear-tippedshort-to-medium-range missile such as the KN-23 at a carrier battle group located in ROK waters
north and east of Busan. The combination of the weapon’s accuracy (good to approximately 100200 m when using conventional warheads42) and the size, spread during travel, and movement of
the battle group mean that the bulk of the ships in the group avoid serious damage, but blastoverpressure damage to superstructures and radiation exposure to the sailors on most ships issubstantial.43 As a rationale for attack, the DPRK could claim that US ships were carrying
nuclear weapons—which is not inconceivable, given past practices and changes in nuclearweapons-at-sea policy changes under the administration of former US President Donald
Trump—and thus the strike was to preempt imminent nuclear weapons use by the United

will-only-use-nuclear-weapons-if-sovereignty-is-threatened. As noted above, however, other statements by the
DPRK over the years on the topic of first use have sometimes appeared to take different positions.
42
See, for example, Michael Elleman (2019), “North Korea’s New Short-Range Missiles: A Technical Evaluation,” 38North, dated, October 9, 2019, and available as https://www.38north.org/2019/10/melleman100919/
43
A discussion of the use of nuclear weapons by the DPRK for attacks on ships is provided in David Wright (2022),
The Role of Missile Defense in North-East Asia, paper prepared for the Reducing the Risk of Nuclear Weapons Use
in Northeast Asia project, January 12, 2022, and available as https://www.apln.network/projects/nuclear-weaponuse-risk-reduction/the-role-of-missile-defense-in-northeast-asia as well as on the RECNA and Nautilus websites.

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States.44 And/or, the DPRK could claim that the presence of the battle group was interpreted tomean that the United States and ROK had plans to attack the DPRK within days.
Given the frequent presence of carrier battle groups in the region, and the historical presence ofUS nuclear weapons on ships at sea, such claims by the DPRK could be considered mostly asmeans to justify its attack to its own people, whereas the main reason for the attack, as with theother variants above, is to renew international attention on the DPRK’s security and economic
situation.
How the Conflict Evolves
Variant 1: Convinced that the nuclear attack on a low-value ROK target is the first salvo of what
will be a more extensive attack, the US/UN Command focus a conventional attack on the
DPRK’s artillery units near the DMZ, but the United States also uses one or more nuclear
weapons on known buried targets thought to conceal ICBMs and other nuclear-tipped missiles
thought to be capable of threatening the United States and its allies. The US nuclear attack uses
weapons designed to destroy exposed and hidden nuclear facilities, but avoid heavily populatedareas and non-military targets, including DPRK leadership, and uses low-yield and low-fallout
weapons when possible,45 in part at the request of the ROK.
Variant 2: The US/UN Command/ROK begins deployment and issues preliminary orders for acounterattack with conventional forces to defend Seoul, with a planned US nuclear counterattack
targeted on known nuclear assets, but neither are ultimately carried out due to successful andspeedy diplomacy.
Variant 3: The attack on the US Navy carrier battle group, with its attendant damage to ships andradiological impact on sailors would likely be enough to induce the United States to use nuclear
weapons on military targets in the DPRK to augment the use of the ROK’s conventionalweapon-based “WMD Response System.”46 The US president in the White House at the time of
the attack may also, like Harry Truman at the outset of the Korean War, believe that not
responding to an attack on US warships would result in an unacceptable setback to the UnitedStates’ military and leadership standing internationally.47 In addition, the proximity of the attack

44

See, for example, Robert S. Norris & Hans M. Kristensen (2016) “Declassified: US nuclear
weapons at sea during the Cold War”, Bulletin of the Atomic Scientists, 72:1, 58-61,
https://www.tandfonline.com/doi/pdf/10.1080/00963402.2016.1124664
45
For a discussion of the possible roles for use of these low-yield weapons, see Eva Lisowski (2021), Potential Use
of Low-Yield Nuclear Weapons in a Korean Context, paper prepared for the Reducing the Risk of Nuclear Weapons
Use in Northeast Asia project, October 2021 (publication forthcoming). An additional reference on tactical or nonstrategic nuclear weapons, many of which are low-yield weapons, is US Congressional Research Service (2021),
Nonstrategic Nuclear Weapons, updated July 15, 2021, and available as https://sgp.fas.org/crs/nuke/RL32572.pdf
46
The ROK’s “WMD Response System” is described by Lee Sangkyu (2021, ibid) as “consisting of a ‘strategic strikesystem’ and the ‘Korean Air and Missile Defense (KAMD)’ to secure autonomous deterrence and response
capabilities.”
47
The history of Truman’s decision to respond to the DPRK’s attack in 1950, and surrounding events, is provided inJames I. Matray (2021), U.S. Entry into the Korean War: Origins, Impact, and Lessons, paper prepared for the
Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, December 16, 2021, and available ashttps://www.recna.nagasaki-u.ac.jp/recna/psnanews/29548 as well as on the APLN and Nautilus websites.

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to both the ROK and Japan, and probable radiological fallout in parts of one or both countries(and/or damage to ships and impacts on mariners from ROK and Japanese ships in the region)
cause the ROK and Japan to insist that the United States retaliate. The United States does so,with a combined nuclear and conventional attack focused on known nuclear facilities in the
DPRK, largely as in Variant 1.
Use Case Consequences
Variant 1: Assured by an immediate, high-level diplomatic mission that the United States has nointention to either take over the DPRK or to advance militarily in Northeast Asia, and facing
internal struggles of its own, China deploys some additional troops to the region near the DPRK
border but refrains from either invading or significantly menacing an invasion. Russia likewise
goes on somewhat higher alert, but largely remains an observer, as does Japan. The broader
international community, lea by the EU and perhaps Southeast Asian states and Australia/New
Zealand, immediately calls for a ceasefire on both sides and offers to mediate the conflict, whichhelps to induce the combatants to consider diplomacy.
When the dust clears from the nuclear exchange, all parties, suitably shaken by the close callwith regional/global disaster, agree, for the first time in many years, to undertake negotiations inearnest, starting with a deal for the DPRK to allow the IAEA (International Atomic Energy
Agency) in to inspect damaged and undamaged nuclear facilities in exchange for international
support,48 first for the clean-up of the damage caused by the US attacks plus massive
humanitarian assistance for its population, and later for assistance in rebuilding its economy.
Over time, this exchange leads to a gradual opening of the DPRK, for which Chairman Kim Jong
Un takes credit, and more economic and social interaction with the ROK, leading, eventually(perhaps by 2045) to de-facto economic integration of the Peninsula.
Variant 2: Challenged by internal issues, possibly including an upwelling of support forprotesters in Hong Kong and/or continued disputes with Taiwan, with conflicts relating to its
territorial disputes in Southeast Asia continuing to simmer, and thus hoping to reduce tensions on
at least one front, China supports renewed negotiations between the DPRK and the international
community, and Russia, quietly assured that it will have a chance to trade with the DPRK,
possibly by electricity to the DPRK and through the DPRK to the ROK, in a new regional
cooperation arrangement, also supports negotiations, as does the international community.
Variant 3: The scale of the US counterattack convinces the DPRK that attacks, either
conventional or nuclear, on its leadership and ground troops are imminent. As a result, the DPRK
begins an all-out conventional war on the ROK, and successfully launches a few of its remaining
missiles on targets in Japan and the United States, resulting in extensive damage and rendering

48

Although the IAEA currently has roles in inspecting civilian (or at least nominally civilian) nuclear facilities aroundthe world to help assure that proliferation of nuclear weapons does not occur, it does not currently, as weunderstand it, have the specific authority or mandate to inspect or safeguard nuclear weapons or weapons
production facilities themselves. It is therefore only our assumption, at this time, that the IAEA or anotherinternational agency, presumably tasked by the United Nations Security Council or a treaty organization, would be
deputized to watch over nuclear weapons systems in the DPRK as a part of an agreement on the DPRK’s nuclear
weapons program.

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43some areas uninhabitable. The DPRK attacks on Japan and the United States described above inturn induce the United States to use tactical nuclear weapons on DPRK ground troops andmissile launchers North of the DMZ, and to attempt to focus attacks on DPRK leadership as
well. Again, China and Russia, depending on how far North the war spreads, may choose to waitout the war rather than support the DPRK. Europe and the rest of the international community
attempts to mediate the crisis, but with attacks and counterattacks happening rapidly, fails to
induce the combatants to relent in time to significantly reduce the war’s damage.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
A key uncertainty in this use case is whether the United States (with nuclear and non-nuclear
forces) and UN Command and the US-ROK Combined Forces Command (with conventional
forces) would be able, given existing military doctrine and procedures, to refrain in the first twovariants from attacking DPRK leadership, or at least command-and-control facilities, which may
by definition necessarily include DPRK leadership. If such an attack does occur, whether or not
it is successful, a significant DPRK nuclear counteroffensive may also be anticipated.
Assuming the use case plays out along the lines of one of the first two variants above, the actors
involved, and onlooking powers, could take heed from what could have evolved into a more
serious unclear exchange and make additional efforts at nuclear arms control beyond the Korean
Peninsula.
Early policy lessons from this case include the need, in the event of a DPRK incursion or attack,to take stock of DPRK intentions before firing back, and to be ready to deploy high-level
delegations to the DPRK and China when needed.

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3.1.2“The Best Defense is a Good Offense”49

In the three “The Best Defense is a Good Offense” variants described below, changes in UnitedStates and ROK behavior leave DPRK leadership convinced that an attack in its territory isimminent, and it launches what is effectively a preemptive strike. The first two variants provided
vary with respect to both the degree to which the ROK/US Alliance remains intact and to the US
response. The third variant, which involves an attack on a nuclear power reactor in the ROK, isdesigned to sow sufficient chaos within the ROK that the United States and ROK are distracted
from mounting an invasion, and the DPRK has time to both plan an effective defense and sue forpeace. Of these, the first two fall at the “unintentional” end of the unintentional-to-intentional
nuclear weapons use spectrum because they arguably are based on a DPRK misunderstanding of
the ROK/US intent to invade. The third variant, although still based on a misunderstanding ofadversary intent by the DPRK, invokes more elements of coercion in its design to create achaotic situation, and can thus be considered more toward the intentional end of the spectrum
than the first two variants.
Triggering Events and First Use
Variant 1: Perhaps due to recent leadership changes, leadership in both the United States and the
ROK reject engagement with the DPRK, instead doubling down (placing additional emphasis)on the use of economic sanctions, building up of conventional armaments (and possibly troops)
near the DMZ and in the ROK generally, increased tempos of war games, and installation ofincreasingly numerous and more modern ROK anti-ballistic missile (ABM) batteries and/or
other deterrents. A sub-variant here might include compliant US leadership acceding to thedemands of a new and hardline ROK administration to redeploy nuclear warheads and delivery
systems to the Korean Peninsula.50 The intent is to get the DPRK to negotiate through applying
maximum pressure, short of direct military incursion, but the tactic backfires. Unable to sustain
investments in new armaments to compete in the “arms race” with the ROK and the UnitedStates, and facing increasing pressure domestically due to lack of basic necessities, the DPRK
leadership becomes convinced that invasion by ROK/US/UN forces is imminent andbecomes even more overwhelmingly convinced that they both are unlikely to win in aconventional war and unlikely to be treated fairly if they engage in diplomacy. Feeling thepossibility of regime collapse due to domestic hardships, and calculating that it will be possible
to sue for peace if sufficient US casualties are incurred—that is, betting that the United States
will have no “stomach for war” when it actually happens, the DPRK uses one or more nuclear
weapons on a major US base in the hope of prevailing. Fearing that (additional) threats ofnuclear use in its current situation will simply result in a pre-emptive strike on its territory by the49

Ideas for this case came from several Consultative Group members and are also similar to variants in the DavisBennett (2021, ibid) paper.
50
See, for example, Yonhap News Agency (2021), “Yoon says he will request redeployment of U.S. tactical nukes incase of emergency,” dated September 22, 2021, and available ashttps://en.yna.co.kr/view/AEN20210922005300320

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45United States and/or reduce the effectiveness of its strike, the DPRK uses its nuclear weapons
without a specific warning of use.
The DPRK thus targets one or more major USFK (United States Forces in Korea)/ROK bases in
the ROK (such as Camp Humphreys, south of Seoul), or perhaps a base in Guam with one ormore nuclear weapons, seeking to cause significant casualties. The timing of this attack might berelatively random by year within 2025-2030, triggered by a particular piece of news or
intelligence (true or false) reaching DPRK leadership regarding ROK/USFK capabilities or
intentions, or could be specifically chosen to strike while the ROK and/or United States areotherwise engaged, such as late in an election cycle or as new leadership takes office that is
expected to be unfavorable to engagement with the DPRK. If it has a choice, the DPRK might, tolessen the probability of a cloud of radioactivity traveling north from a target in the northern partof the ROK, choose to attack in the winter, though the timing during the year of an attack on, forexample, Guam, would not presumably matter much to the DPRK.
The DPRK would likely use the KN-23 missile for the attack, a look-alike to the Russian“Iskander-M.”51 Detonation would be designed to inflict major casualties on a specific area aswell as disable/render inoperable (due to radiation) significant military infrastructure, especially
ABM batteries and aircraft.
Variant 2: With leadership in the United States and ROK distracted by domestic issues, noprogress is made on engagement, sanctions continue in place and become more effective due toimproved enforcement, and the DPRK leadership feels that its population is close to the breaking
point due to lack of food and supplies, possibly exacerbated by increasingly frequent extreme
weather. In this case, distractions for United States and DPRK leadership might include thesweeping effects of the highly transmissible COVID-19 “Omega-Delta” variant,52 more active
domestic extremism in the United States, an economic downturn (perhaps due to COVID) and/or
a rupture in the ROK/US relationship due to the ROK being found to be working on nuclear
weapons53 because its confidence in the US nuclear umbrella is failing, as it perceives the UnitedStates to be increasingly focusing inward and on other parts of the globe, and less on Korea. As
the DPRK sees the army defending the ROK getting smaller (due, for example, to the effects of
COVID-19 measures, budget cut-backs in the ROK/US, or a US military refocusing elsewhere),
the DPRK leadership becomes convinced that its international situation and domestic
standing offer an opportunity to move on the ROK, and that it can only do so successfully
by attacking a US base with a nuclear weapon, which, it feels, would leave the United Statessuing for peace and put the DPRK in a favorable position for negotiations. As a result, the DPRK
takes the initiative to attack the ROK’s 12 airfields, with missile defense systems also being

51

See, for example https://missilethreat.csis.org/missile/kn-23/
Although this naming and timing for a COVID-19 variant is of course for expository purposes only, the probability
sadly seems high, given recent (2020-2021) experience, that the number of COVID-19 variants the world will haveexperienced will outstrip the number of letters in the Greek alphabet by the time this variant is posited to occur,during the 2025-2030 timeframe.
53
The ROK has previously, and in violation of its agreements with the IAEA, undertaken experiments in extraction
and reprocessing of plutonium. See, for example, GlobalSecurity.org (undated, but after 2004), “Weapons of Mass
Destruction (WMD), Nuclear Reprocessing,” available as https://www.globalsecurity.org/wmd/world/rok/nuclearreprocessing.htm, and Anastasia Barannikova (2021), ibid.
52

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potential targets for special forces to attack, as well as ports and other military facilities.
Although the DPRK could do significant damage to the bases with conventional rockets,
Jungang and other ROK bases have underground shelters that would be hard to render ineffectivewith conventional missiles. Disabling these bases would require nuclear weapons to either
destroy them or to make them inaccessible due to fallout.
Variant 3: The circumstances outlined in Variant 1, perhaps enhanced by some of the DPRK
domestic-front challenges described for Variant 2, convince the DPRK that it will be possible toavert a perceived ROK/US invasion and set the stage for a diplomatic “win” through a covert
attack on the ROK. Having noted the chaos visited on Japan during the Fukushima reactor
accident in March of 2011—caused and exacerbated, of course, by the terrible damage from the
Tohoku earthquake and subsequent tsunami—DPRK leadership dispatch teams of Special Forces
units, possibly including “sleeper” units prepositioned in the ROK as well as units arriving
through undiscovered DMZ tunnels and by sea via, for example, disguised ships andsubmarines.54
These teams coordinate to attack one or more reactor sites in the ROK (each of which hosts
multiple reactor units), focusing on relatively vulnerable ancillary systems, such as power
supplies, cooling equipment, control systems, and spent fuel pools.55 ROK reactors are welldefended, and given ROK experience with previous covert attacks by DPRK infiltrators, will
have explored and be ready deal with many possible attack routes. It is possible that, recognizing
this, the DPRK teams will either attack multiple sites, or will coordinate attacks such that a firstattack or a nearby diversionary attack depletes the security forces/defenses around the reactor,
while one or more other teams attack the plant itself. To assure enough damage to a reactor site
to cause significant chaos and upheaval in the ROK, this use case posits that the DPRK Special
Forces teams attempt to deploy and detonate nuclear weapons carried into vulnerable power
plant locations by hand and/or in small and maneuverable vehicles.
Alternatively in Variant 3, in recognition of the strength of ROK defenses around reactors, theDPRK may use a nuclear-tipped cruise missile to attack an ROK reactor.56 These missiles aremaneuverable, potentially accurate to within a few meters (although the full capabilities of the
DPRK’s cruise missiles are probably not yet clear), and may be able to evade ABM defenses

54

One account of the activities of DPRK operatives in the ROK is found in Laura Bicker (2021), “Drugs, arms, andterror: A high profile defector on Kim's North Korea,” BBC News, dated 11 October 2021, and available ashttps://www.bbc.com/news/world-asia-58838834
55
The vulnerabilities of nuclear reactor systems to accident or attack, and measures to reduce thosevulnerabilities, have been studied for decades, and are described in a variety of books and articles in the open
literature. See, for example, Robert Alvarez, Jan Beyea, Klaus Janberg, Jungmin Kang, Ed Lyman, Allison
Macfarlane, Gordon Thompson, and Frank N. von Hippel (2003), “Reducing the Hazards from Stored Spent Powerreactor Fuel in the United States,” Science and Global Security, 2003, vol. 1, no. 1, pp 1-60, available ashttps://scienceandglobalsecurity.org/archive/sgs11alvarez.pdf; and Mark Holt and Anthony Andrews (2014),
Nuclear Power Plant Security and Vulnerabilities, United States Congressional Research Service RL-34331, available
as https://sgp.fas.org/crs/homesec/RL34331.pdf
56
See, for example, Ankit Panda (2021), “Why North Korea's cruise missile launch could worry other nations,” BBC
News, dated 17 September 2021, and available as https://www.bbc.com/news/world-asia-58592308

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placed near reactor sites, even if their launch was detected, particularly given the short flighttime between the DPRK and the ROK.
Whichever attack mode is used in Variant 3, depending on how effective the attack is intargeting the nuclear plant, the result could couple the immediate release of radiation from thenuclear detonation with a perhaps slowly-evolving meltdown of spent reactor fuel, if one or morespent fuel pools are affected and lose cooling and/or if one or more reactor cores are breached
and/or lose cooling by some other means. The combination would likely create a crisis in the
ROK, with large populations attempting to move to get away from the fallout resulting from boththe NUDET and reactor fuel damage,57 with chaos compounded by the likely partial shut-downof the ROK electricity grid.
How the Conflict Evolves
Variant 1: The United States responds with conventional missile (and bomber) attacks on
military installations, but it also uses one or more nuclear weapons on sites that are thought tohouse ICBMs or other nuclear-tipped missiles and at least one weapon on a site in or near
Pyongyang thought to house a command bunker. The United States would have to weigh theprobability of an attack on its own territory and/or additional bases in responding, but in thisinstance would face pressure both domestically and from allies (the ROK, likely Japan, andpossibly Europe) to respond, and might conclude that the DPRK’s ICBM and medium-range
missile technologies, at least when mated to nuclear warheads, have not evolved to the point
where they are likely to be effective. This conclusion would probably be easier for the UnitedStates to reach in 2025 than in 2030, assuming no or limited engagement takes place between
now (early 2022) and then, and that as a result the DPRK’s weapons technology development(and/or acquisition) continues. Nuclear weapons to be used by the United States would be
missiles expected to be accurate enough to hit small and often hardened targets, including
weapons designed to “bust bunkers” and deployed to do so.
Variant 2: The US/UN Command targets for conventional weapons in retaliation are as above.58
The likelihood of the United States using nuclear weapons would be increased if US leadership
became convinced that it would be possible to reliably destroy the DPRK’s nuclear arsenal
and/or nuclear missile systems. A sub-variant could be that the United States and allied forces
explicitly stop short of destroying the DPRK’s leadership, and possibly stop short of destroying
all of the DPRK’s nuclear arsenal (those elements for which locations are known) in order tooffer the DPRK a peace deal that stops short of the destruction of the DPRK state and to assurethat an intact DPRK government exists as a counterpart for negotiations. As noted in the57

Most of the ROK’s reactor sites are located in the southern half of the country. Depending on prevailing winds at
the time of the attack, mass movements of populations north toward Seoul from southern or eastern areas of the
ROK could result from the attack, either to avoid the real danger of a radioactive plume and/or as a result of panicat the potential evolving impacts of the reactor damage and resulting plume.
58
It has been noted that although there was a UN role in the Korean War and is a UN role in defending the ROK,
the UN is unlikely to be involved in the use of nuclear weapons, so any counterattacks on the DPRK (or others)
using nuclear weapons—of first use of nuclear weapons in some of the cases below—will be carried out under US,
not UN, command.

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previous use case, however, such restraint may run counter to US/USFK/ROK forces doctrine
and programming.
Variant 3: Faced with the immediate and evolving fallout threats to the ROK population, ROK
and US military and civilian planners are forced to make a choice as to whether to offer some
sort of a truce deal to the DPRK, or to assume that the attack on the reactor was a DPRK
preamble to a much broader offensive by the DPRK that could be expected immediately, and/orthat the DPRK would reject, delay implementation of, or fail to honor a truce, and an immediate
counter-offensive against the DPRK would thus be needed. In this instance, it is assumed that
US/ROK leaders conclude that the DPRK plans to attack within hours or days, and that withmuch of the ROK (and its military) occupied with managing the upheaval resulting from theattack on the reactor (probably with US soldiers helping ROK troops and organizing massive airand sea evacuations out of the ROK), the only way to avoid an all-out invasion of the ROK
would be to target DPRK troop concentrations and leadership with air power delivering
conventional bombs and then with nuclear weapons delivered with bombers and ground and sealaunched missiles.
Use Case Consequences
Variant 1: Through a combination of successful attacks on the DPRK's nuclear and military
infrastructure and some luck—perhaps Kim Jong Un and his inner circle are killed or leave thecountry, perhaps some of the missiles, most notably the ICBMs, fail to operate—the DPRK
leadership, to the extent it remains, is obliged to offer peace terms that feature IAEA or UN
access to and control over the DPRK's nuclear weapons facilities in exchange for the equivalentof a "Marshall Plan" for the DPRK (and the damaged areas of the ROK), paid for by aninternational group of donors led by the United States and Japan. Once the DPRK's nuclear
weapons are secured, and reconstruction/redevelopment is underway, a formal peace treaty issigned between the parties to the Korean War. The DPRK and ROK remain separate, but aprocess of "nation (re)building," on a Western model, begins in the DPRK.
Variant 2 (and sub-variants): Consequences could possibly evolve as above, but in the subvariant where the US and allied forces explicitly stop short of destroying the DPRK's leadership,
perhaps the ROK/US alliance (in the sub-variants where it remains intact or is repaired by thenecessity of war) reaches out to DPRK leadership in a way that allows the latter to save face,offering the combination of peace and significant investment in rebuilding the DPRK economy
in exchange for placing the DPRK's nuclear and missile infrastructure under international control
as a first step in negotiating a nuclear free zone on the peninsula. A similar endgame could occur
if Kim Jong Un is killed or leaves the country, but a replacement group, with a more open
ideology, manages to quickly consolidate power.
In both cases, eager to see the United States weakened by (another) war but unwilling to enter
one themselves, China and Russia accept US assurances that the US goal in using nuclear
weapons in response is limited to reducing/removing further DPRK nuclear weapons threats, andremoving DPRK leadership, but require a deal in advance for significant roles in the governanceof a defeated DPRK, perhaps through the UNSC.

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It seems likely, however, that China in particular, but perhaps both China and Russia would beless willing to exercise restraint if, in fact, the United States had brought nuclear weapons backto the ROK, or would at least require their re-removal to sign off on a deal to end the conflict. As
a consequence, if the United States and/or the ROK balk at removing US nuclear weapons from
ROK territory, the plausibility of China and/or Russia staying out of the conflict may decrease.
Variant 3: In this Variant, the chaos that the DPRK had hoped to sow with an attack on a ROK
reactor backfires for the DPRK because the United States becomes trapped into using nuclear
weapons to thwart a DPRK invasion, as well as targeting DPRK leadership. The resulting
exchange of weapons leaves the southern part of the DPRK impassable and the ROK population
trapped between the DMZ and the smoldering reactor complex in the south. To the extent that its
conventional artillery and/or nuclear weapons survive US/ROK air attacks, DPRK shelling
and/or nuclear use on the Seoul area would compound the misery on the Peninsula. If the DPRK
has operable ICBMs, after (or during) US/ROK attacks, it might well decide to use them toattack the United States, with shorter-range weapons targeting US bases and probably civilian
areas in Japan.
As in the variants above, Russia and China might decide to nervously remain on the sidelines, atleast with regard to nuclear weapons use, and let the war play out, but if the United States targets
the DPRK via overflights of Russian or Chinese territory with missiles or bombers, concern that
the United States may be targeting Russian or Chinese territory may cause those nations tolaunch nuclear weapons at the United States, resulting in essentially global nuclear war as theUnited States responds to Russian and/or Chinese launches.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
In the first two variants above, the DPRK might deploy nuclear demolition mines in key
corridors along the DMZ to block invasion by a US/ROK army and might detonate them if
invasion seemed inevitable. Depending on how many weapons were deployed and detonated, theresult might be an effectively permanent division of the Koreas, at least by land. Alternatively,
DPRK leadership, if not checked by military officers or others in the DPRK, may decide toinflict additional pain on the United States and the ROK through attacks on civilians, possibly
leaving both the ROK and DPRK sufficiently damaged and contaminated as to be partially orlargely uninhabitable in the short term. Such a result would, in effect, underscore a fundamental
problem—if the US/ROK “win” a war on the Peninsula it might in fact, in some circumstances,be worse than losing.
Avoiding this use case (and its variants) underlines the importance of leadership and consistencyor leadership, and of mutual understanding between allies (United States/ROK, UnitedStates/Japan) as to what to expect from each other in different cases. For the United States, thisalso means developing and sustaining an emphasis on maintaining attention on multiple fronts
and on close coordination/cooperation with allies, as well as obtaining a better understanding of
the points of view of its adversaries.
The third variant here, positing an attack on a nuclear reactor, calls attention to particular lessons
as to technology and security planning. These include the need to make spent fuel pools as
secure as possible, provide multiple alternative power sources for reactor cooling, and maintain
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50vigilant security measures at reactor complexes, including imagining and figuring out how tothwart a comprehensive range of potential attack that might be visited on a nuclear power site.
Although it is very hard to plan how to ameliorate a crisis where a large part of the ROK
population may be on the move, one way to provide at least some mitigation of the situation may
be to assure that electricity can be provided in emergency shelters and elsewhere throughout the
ROK on an ongoing basis independent of the central grid, probably through a combination of
distributed renewable generation and electricity storage, such as in “microgrids.”

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3.1.3“Last Option for Survival”

In the two “Last Option for Survival” variants, the DPRK regime finds itself in a position where
it is losing power over its citizens, albeit for different reasons in the two variants, and lashes out
on non-military ROK and US targets with nuclear weapons. In each case, the DPRK attacks are(or are described as) attempts at self-preservation and can be thought of as falling toward the“unintentional” end of the spectrum of attacks.
Triggering Events and First Use
Variant 1: Social unrest in the DPRK, brought on by a combination of increasingly unbearable
deprivations due to a combination of economic isolation, sanctions, natural disasters (and related
crop failures), the unwillingness of the regime to accept help, rampant (if unacknowledged)
COVID-19 infections, and an ever-increasing understanding, through the leakage of news andpopular culture across the border, that life is better in the ROK, causes the DPRK government tofight back in a way that causes further unrest. Seeing a partial collapse of DPRK government, US
and ROK forces come in, nominally to protect DPRK populations, and are only lightly resisted
by DPRK troops, who have also become aware of the stark difference between North and Southand are suffering from lack of food, heat, medicines, and other necessities themselves. Fearing
for its survival, the DPRK leadership orders a nuclear launch.
The DPRK nuclear attack focuses on populated areas, meaning either key areas of government
and/or culture in Seoul. These could include the Blue House and environs, key ministries not yet
moved to the Sejong area, City Hall, and/or a US military base in the Seoul area, with targets
chosen in an attempt to break the conviction of the ROK. The DPRK’s perceptions of theaccuracy of its weapons might influence its choice of targets. For example, the DPRK might
avoid attacking Seoul City Hall due to its proximity to the Deoksugung Palace, if the latter wasconsidered a cultural keepsake by DPRK leadership. The DPRK might alternatively focus on
attacking a nuclear reactor with a nuclear-tipped missile, calculating that a nuclear disaster that
unfolded like Fukushima would distract the ROK and its allies from pursuing war with the
DPRK, and, because most ROK reactors, as they are mostly located in the Southern part of the
ROK, are relatively distant from the DPRK border, reducing the DPRK's exposure to theresulting fallout. An attack on an ROK reactor, if effective, might cause a mass migration of
ROK refugees in the direction of Seoul, perhaps complicating efforts to defend the city.
In its attack, the DPRK would again use the KN-23 missile. This SRBM (short-range ballistic
missile) is designed to follow a relatively low trajectory, and thus be difficult for systems like the
THAAD (Terminal High Altitude Area Defense) missile defense systems deployed in the
ROK.59 The KN-23 can be fitted with either conventional or nuclear warheads, thus potentially

59

See, for example, Missile Defense Advocacy Alliance (undated, but probably 2019 or 2020), “KN-23”, available ashttps://missiledefenseadvocacy.org/missile-threat-and-proliferation/todays-missile-threat/north-korea/kn-23/
See also Matt Korda (2021), Nuclear Weapons and Delivery Systems that Might be Implicated in Nuclear Use
Involving the Korean Peninsula, paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast
Asia project, September 2021 (publication forthcoming).

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causing uncertainty on the part of USFK/ROK defenders, and potentially increasing thepossibility of a nuclear response once a launch is detected. Detonation in this case would bedesigned to inflict major casualties on a specific area for effect on ROK morale. Weapons to be
used by the United States to be determined, but probably would be weapons designed for highly
targeted impacts and limited fallout due to the presence of coalition troops.
In the case where the DPRK’s artillery, anti-aircraft, and other defenses had been depleted during
a conflict, where DPRK leadership saw ROK/US troops coming across the border, and whereleadership saw no other way of stopping the invasion, it is possible that it might use nuclear
weapons on oncoming troops and south-north invasion corridors north of the DMZ, thereby
using nuclear weapons on its own territory to cut off a land invasion and, perhaps, give DPRK
leaders time to retrench, retreat, or leave the country.
Variant 2: In this second variant, the DPRK carries out a provocative attack triggered by
DPRK leadership feeling embattled for reasons including those in Variant 1. Candidates forthe provocation include DPRK Special Forces attacking an ROK government facility or
attempting an attack at a nuclear power plant with a special forces contingent (see above—
although, as noted, nuclear plants are well-guarded in the ROK), or the DPRK initiating anothernaval encounter, or an attack along the DMZ as a result of a mistake by the DPRK incommunicating orders, or a suspected DPRK drone attack on an individual in leadership in the
ROK or USFK. The provocation—possibly one of these or possibly a limited conventional attackby the DPRK, leads the ROK/USFK to conclude that a broader DPRK attack is imminent, andthose forces follow the typical recent game plan of US attacks in such situations in otherconflicts, which is to disable the DPRK's command and control infrastructure with conventional
weapons. The attack on DPRK command and control infrastructure leads the DPRK, andin particular Kim Jong Un, to conclude, perhaps mistakenly (as it is possible that the intent
of an ROK/USFK military incursion might not, in fact, be to topple the Kim regime), thatthe aim of the ROK/USFK attack is regime change in the DPRK, and that the survival of theregime in a continuing conventional war is improbable. As a result, DPRK leadership
launches a nuclear weapon against a target in the ROK, likely focusing on types of targets
identified in Variant 1.
How the Conflict Evolves
Variant 1: Due to the presence of ROK/USFK/UN Command troops in the DPRK, and wishingto limit civilian casualties, the United States would be obliged to use mostly conventional
weapons, and to use limited, possibly low-yield nuclear strikes focused on known DPRK nuclear
missile and other nuclear facilities, and on command-and-control operations not located within
population centers (or near where invading troops are located). It is likely that Yongbyon would
be a target, although it could probably be as easily destroyed with conventional-tipped missiles
or a bombing campaign with conventional munitions. Weapons assumed to be used by theUnited States in its counterattacks are yet to be defined, but probably would be weapons
designed for highly targeted impacts and limited fallout due to the presence of
ROK/USFK/coalition troops in the DPRK.
Variant 2: Here the response of the United States (and conventionally-armed partners) may
possibly be as in Variant 1, although depending on the character of the US president at the time,
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on whether the DPRK has targeted US citizens in its NUDET, and/or whether the US president
becomes convinced by advisors that the DPRK can and will launch an ICBM on US territory, theUnited States might seek to remove DPRK leadership with a targeted attack on Pyongyang.
Use Case Consequences
Variant 1: Worried about US/UN troops presence in the DPRK, and by nuclear use by theUnited States as far north of the DMZ as Yongbyon, and about the flow of refugees from the
DPRK into Northeast China, China masses troops on its border with the DPRK and in someplaces, including, probably, around Dandong/Sinuiju, moves into the DPRK to establish forward
positions, mostly to deter flight north by DPRK citizens, but also to establish a line that US/UN
troops are not to cross. China warns US/UN troops not to move further north, but refrains fromattack, nuclear or otherwise, while the US/UN forces remain south of Yongbyon. Russia moves
troops to its limited border with the DPRK as a precaution, and to deter refugees, but prefers toremain out of the conflict for as long as possible.
Variant 2: If the US attacks Pyongyang, China may be obliged to come to the DPRK's aid.
Given the danger from fallout, aid might not be in the form of Chinese troops on the ground on
the peninsula, but rather in the form of threatened use of ICBMs to US soil. Russia might
retaliate in a limited way for the loss of its citizens in Pyongyang or consider attacks on US basesin Japan or in Europe, though it might not go through with attacks, particularly attacks outside ofNortheast Asia, for fear of starting a global war.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
It may be improbable that the US/ROK refrains from attacking out DPRK leadership, based on
general war-fighting strategy in recent years, and also highly probable that the DPRK leadershipwould expect the US/ROK to refrain from attempting to attack leadership, which would compel
the DPRK to respond in defense of its leadership, even if a US/ROK attack on leadership was infact not planned. Also uncertain is the extent to which China would feel compelled to back up
the DPRK with its own nuclear weapons, particularly if the DPRK was responsible for the
provocation that started the war.
Policy lessons here may be for the international community to try and “keep an eye” onconditions in the DPRK that may affect the stability of the DPRK regime with respect to its
standing among DPRK citizens, and to offer and supply humanitarian aid (food, medicines, andfertilizer, for example) in such a way as to keep conditions in the DPRK from becoming too direand thus unstable.

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543.1.4“We’ve Got Them Where We Want Them”

In “We’ve Got Them Where We Want Them,” the DPRK regime comes back to the bargaining
table for talks about its nuclear program and related issues, and although progress in negotiations
appears from the perspective of the international community to be positive, if slow, the true
intent of the DPRK is to reunify the Peninsula under DPRK rule, by force, if necessary, and it
waits for a moment when it feels that the US and ROK military forces on the Peninsula areweakened and off-guard to mount a full scale attack on the ROK. The long-term planning
involved in this use case puts it at the deliberate/intentional portion of the range of reasons fornuclear first use.
Triggering Events and First Use
Playing the long game and taking advantage of inadequate communications between a distracted
United States that is trying to reduce its international exposure to conflict and an ROK
administration focused on making progress through diplomacy, the DPRK engages innegotiations on its nuclear program for 2-3 years. These negotiations offer sufficient hope to theUnited States of a long-term solution that the United States reduces military exercises with the
ROK and begins to deploy troops formerly part of USFK to conflict zones elsewhere. The
DPRK, however, although offering sufficient concessions (though all easily reversible) to keep
the United States and others at the negotiating table, remains focused on a Korean Peninsula
united under DPRK rule. As US forces are called to a conflict elsewhere—perhaps in the Taiwan
Strait, perhaps in the Middle East, or both—the DPRK takes advantage of the situation by
rapidly expelling (or possibly detaining as hostages) international nuclear
weapons/facilities inspectors, attacking US bases in the ROK and the region with nuclear
weapons, and simultaneously launching a full-on conventional offensive across the DMZ,
albeit focusing on military targets.
With a focus on winning a war and being left with usable ROK infrastructure after the war, theDPRK focuses its nuclear attacks on military targets—major US bases, including in Okinawa (itperhaps targets Guam as well, but the missile headed for Guam malfunctions or is intercepted),
ROK mobile forces, resupply infrastructure, and especially ROK/US air power. It uses weapons
designed to inflict damage on military installations, but limit damage to key civilian
infrastructure, and limit fallout damage, for example, to agriculture. It may plan the attack for aseason when winds blow north to south, such as in the winter, to reduce fallout on the DPRK andto avoid the growing season for agriculture (although that may or may not help to render agreater area of the next year’s crops radiologically safe).
How the Conflict Evolves
Caught off-guard, and fearful of being overrun, the ROK reluctantly asks the United States to use
nuclear weapons in response. The United States reluctantly agrees and uses nuclear weapons,
likely fired from ships at sea, submarines, or from land-based installations further afield, toattack known nuclear facilities and weapons systems in the DPRK, as well as conventional
missiles and bombs in an attempt to slow the progress of the DPRK offensive. The US
counterattack would probably also target suspected DPRK leadership bunkers and areas where
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additional forward-deployed troops and armaments are stationed, north of the DMZ, but
probably would spare civilian areas to the extent possible.
Use Case Consequences
Because the DPRK is the aggressor in this use case, China would go to high alert, watching for
US military incursions that might threaten Chinese territory or threaten Chinese nationals orbusinesses in the DPRK, but it would not use its nuclear weapons against US or ROK targets.
Russia would do likewise. The result would be a nuclear war largely contained to the Korean
Peninsula and Okinawa, but likely resulting in the deaths of millions of people, and hundreds ofbillions of dollars in property damage. The attack on Okinawa brings the Japanese Defense
Forces into the conflict, probably in areas of the DPRK not affected by fallout, which are closeenough to the Chinese border that China’s alert status rises further, and it deploys troops to theborder to guard against a military incursion and to stem the flow of DPRK refugees, which
mounts rapidly as a humanitarian crisis in the DPRK unfolds.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
This case offers a number of uncertainties that may call its plausibility into question. For
example, would the DPRK really attack the ROK unprovoked while negotiations were
continuing? Would DPRK leadership have sufficient "hubris" to believe the United States
wouldn't counterattack, or be somehow sufficiently convinced by DPRK military leaders that nocounterattack would be forthcoming? Also, is it reasonable to assume that the DPRK candevelop low-yield or specialized nuclear weapons by 2030, and if it doesn’t have them, would it
be willing to accept contaminating ROK infrastructure to the degree that non-specialized
warheads would tend to do?
Further, with respect to China and Russia, US ship- or submarine-launched counterattacks on the
DPRK could, given the very limited flight time of missiles to their targets, trigger Chinese or
Russian counterattacks on the United States, as China and Russia might not be able to know thatthe missiles are not targeted at them, or if Chinese and/or Russian military doctrine call for a
response to any ballistic missile launch from the United States at sea. And if Japan joins US
troops on (less- or uncontaminated) parts of the Korean Peninsula, would it bring China into thewar as an active participant? It seems possible that China’s considerable economic interests in
the ROK, Japan, and the United States would make Chinese leadership reluctant to join a war
that it did not start and does not seem to be affecting its territory, but that is certainly not a given.
Initial policy lessons from this case might be to include sufficient inducements, both positive andnegative, in negotiations and incremental agreements as to make the interruption of the processof diplomacy unattractive for all parties, and to maintain attention on ongoing negotiations andcommitments despite other distractions.

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3.1.5"Help Not Wanted"

The “Help Not Wanted” case varies considerably from the other DPRK-as-first-user cases abovein that the target of DPRK nuclear weapons are not in the ROK or US military assets elsewherein the region, but are in China, and designed to combat what it sees as a takeover of the DPRK
by China. In this case the DPRK nuclear weapons use, as it is in response to an unexpected
invasion (whatever its purpose) by China, falls at the “unintentional” end of the spectrum of
reasons for nuclear first use.
Triggering Events and First Use
The joint impacts of UNSC sanctions, increased international vigilance toward sanctionsbreaking "unofficial" imports of energy and other goods (and exports of coal), natural
disasters/crop failures, and perhaps a wave of a new COVID-19 variant cause DPRK governanceto begin to fray. This is manifested first by a loss of control in the northern DPRK provinces,including the defection from their posts (if not from the DPRK itself) of a significant number oftroops stationed in the area, possibly with a renegade army officer becoming a kind of "warlord"in the region. Fearing a total collapse of the DPRK government, and already seeing muchincreased flows of refugees across its border, Chinese forces begin to move into the northern
DPRK to keep the peace. Fearing being overrun, unable, unwilling, or afraid to redeploy
troops from the DMZ, and with no control over their troops in the North, the DPRK
leadership responds with the use of nuclear weapons in an attack on China.
In this attack, one or more DPRK nuclear weapons are used on military targets in the Shenyang
Military Region,60 although that Command has been superseded by the Northern Theater
Command.61 Targets might include military bases in the area,62 but could also include key roads
leading to bridges into the DPRK, with a goal of making the border less passible to groundtroops. There is, for example, a military airfield in Dandong, close to the bridge across the Yalu.
But it would seem that attacking that location—or probably any location in China—would prettymuch mean the DPRK had given up on China as a partner, as it would almost certainly mean
cutting off the DPRK's major source of crude oil as well.
How the Conflict Evolves
China's response focuses on eliminating nuclear weapons and delivery systems that would
continue an attack on China, mostly through conventional attacks, but possibly with tactical
nuclear weapons to address deeply-buried and critical targets. China is aided in this effort by its
inventory of on-the-ground intelligence on the DPRK's nuclear arsenal, information that it has

60

See, for example, "Shenyang Military Region, Shenyang Military Area Command," ascribed (by Wikipedia) toJohn Pike (2006), https://www.globalsecurity.org/military/world/china/shenyang-mr.htm
61
Wikipedia (2016), “Northern Theater Command”, available ashttps://en.wikipedia.org/wiki/Northern_Theater_Command62
A summary of the air bases in the area is provided at Wikia.org (undated), “List of People's Liberation Army Air
Force airbases,” available ashttps://military.wikia.org/wiki/List_of_People%27s_Liberation_Army_Air_Force_airbases

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gathered during its business and other dealings with DPRK actors, but which it has not sharedwith other nations. China does not seek to overthrow the Kim regime using nuclear weapons dueto (A) fear of fallout on its own territory (if summer and prevailing wind patterns are south tonorth) and/or (B) not wishing to subject the ROK to fallout and bring the ROK and the UnitedStates (and allies) into the conflict, probably resulting, at best, in the long-term economic
isolation of China. Instead, Chinese army finds and "detains" Kim Jong Un and his inner circle,
taking them to Beijing for "consultation."
Use Case Consequences
USFK/ROK troops go on heightened alert along the DMZ, and Russian troops mass at their shortborder with the DPRK, but neither crosses the line, at least while China has a military presencein the DPRK. Rather, the United States seeks a negotiated treaty with China and Russia
regarding self-governance of the northern part of the Korean peninsula, or at least of the eventual
stationing of USFK troops no further north than Yongbyon (for example). One could maybe see
a scenario where if the DPRK troops defending the DMZ pull back, lay down their arms, and/or
defect, or in which the ROK, in fact, opens its border to incoming refugees, and effectively
works with them to open the DMZ (for example, to demine it and remove razor wire). The ROK
government would probably at that point seek aid from the United States and EU to allow it toabsorb the refugees.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Key uncertainties in the evolution of this case include:•

Whether the DPRK leadership truly fears a Chinese invasion enough to attack China
with nuclear weapons, or, alternatively, would trust China to help DPRK leadershipbring restive areas of the DPRK back under central control, and then, having done so,
depart, rather than making the DPRK a de-facto client state of the PRC. This uncertainty
might be thought of as how the balance plays out between China’s considerable recent
economic role in the DPRK and shared socialist philosophies and the DPRK’s reported
rhetoric, in “ideological study sessions,” describing China as “the enemy of the last 1000
years.”63•

Whether the US/ROK would come to the aid of rebels in the North of the DPRK, leaving
troops in harms way when China counterattacks, and possibly triggering a response with
US nuclear weapons on China, in all likelihood then leading to a broader nuclear
exchange.

63

An AsiaPress.org article entitled “’The Enemy of a Thousand Years’: Anti-Chinese Public Sentiment Constrains
Cross-border Cooperation,” dated July 9 2019, described “harsh rhetoric targeting China [as being] used frequently[during the Kim Jong Un era] by citizens at ideological study sessions, such as ‘If Japan is the enemy of the last 100
years, then China is the enemy of the last 1,000 years’ and ‘We should not have any illusions about China.’” Article
available as https://www.asiapress.org/rimjin-gang/2019/07/society-economy/the-enemy-of-a-thousand-yearsanti-chinese-public-sentiment-constrains-cross-border-cooperation/

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•Whether the United States, ROK, or Japan would mistake the firing of nuclear weaponsby China, possibly from bases in North China or from submarines or ships, to be the startof attacks on their territory, and follow with nuclear and conventional attacks of theirown on Chinese soil.

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593.2 United States/ROK as First User
In the following three cases (some with variants), the United States is the first user of nuclear
weapons on or near the Korean Peninsula. Although the United States has a nominal (if not
explicit) no first use policy,64 in most of the cases below, a provocation by or attributed to the
DPRK induces a United States that, due to its position at the time, perceives (rightly or wrongly)
few viable non-nuclear options, to use nuclear weapons. If the US policy on first use changes in
the near future, and particularly if it appears that change would survive in future administrations,the plausibility of some of the cases below might be reduced. In one case the use of nuclear
weapons hinges mostly on the personality of the US president— though it can easily be argued
that any use of nuclear weapons, anywhere, depends on the personality of the US president, andon those who provide information and advice to him or her. Many of the cases presented below
draw upon or have elements of ideas developed in a paper prepared for this project by Daryl
Press.65
3.2.1"The Best Defense is a Good Defense"

In response to a spreading ground war across the DMZ and feeling in danger of US/ROK/UN
Command troops being overrun, the United States resorts to nuclear weapons use to stem a
DPRK attack. Given that this action is in response to an evolving and uncontrolled situation, US
first use in this case can be considered at the unintended end of the range of reasons for nuclear
first use.
Triggering Events and First Use
A ground war breaks out between the DPRK and the ROK, perhaps because, due to lack of intermilitary communications, the DPRK mistakes ROK/US exercises for an imminent attack, and/or
perhaps because DPRK internal politics are coming to a head and the DPRK leadership needs adiversion, and/or for some other reason, which could be an accidental missile launch into the
DPRK from the ROK, or an ROK patrol boat being sunk by a DPRK submarine in disputed
waters (to give just two examples). With the United States distracted by wars elsewhere and/or
contentious elections and/or natural disasters/pandemic and/or governed by a president unable orunwilling to commit additional troops to the Peninsula, the ROK/USFK is unable to bring
reinforcements to the Peninsula in a timely fashion as DPRK troops stream across the DMZ,

64

In a recent summary, the US Congressional Research Service (CRS) noted, with respect to the US Joseph Biden
Administration’s consideration of a change in first use policy, that a ‘no first use’ policy would represent a change
from current policy, where the United States has pledged to refrain from using nuclear weapons against most nonnuclear weapon states, but has neither ruled out their first use in all cases nor specified the circumstances underwhich it would use them.” CRS (2021), U.S. Nuclear Weapons Policy: Considering “No First Use”, updated October
13, 2021, and available as https://sgp.fas.org/crs/nuke/IN10553.pdf
65
Daryl G. Press (2021), The Deliberate Employment of U.S. Nuclear Weapons: Escalation Triggers on the Korean
Peninsula, paper prepared for the Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, January 6,
2022, available as https://www.apln.network/projects/nuclear-weapon-use-risk-reduction/the-deliberateemployment-of-united-states-nuclear-weapons-escalation-triggers-on-the-korean-peninsula and on the RECNA
and Nautilus Institute websites.

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possibly taking ROK hostages as they go. As a consequence, at least initially, the ground war
goes well for the DPRK, perhaps aided by adroit and timely work by DPRK Special Forces cells
prepositioned in the ROK to disable much of the ROK/USFK air power. Fearing being
overrun, the United States first threatens nuclear use on DPRK territory, but when thatthreat apparently goes unheeded, the United States/ROK resorts to a targeted nuclear
attack to decimate second-echelon forces (troops, tanks, and artillery) stationed north of
the DMZ.
US nuclear attacks focus on DPRK military units located North of the DMZ and staging forinvasion of the ROK, as well as key batteries of missile launchers threatening Seoul, althoughsome of the latter could be carried out with conventional missiles or aircraft. The United Statesmight feel obliged at the same time to try and remove as much of the DPRK's nuclear threat as
possible. There may be enough uncertainty in the efficacy of conventional first strikes on
facilities in the DPRK that the United States might decide it couldn't be sure of disabling key
DPRK threats without using nuclear weapons.
How the Conflict Evolves
Fearing an attack on its leadership, in addition to its military units, the DPRK launches a nuclear
attack on a major US base in the ROK, and/or on US bases in the region (Okinawa or Guam)
where the DPRK calculates US nuclear attacks might originate. Examples of military targets forthe DPRK might include the Jinhae US naval base near Busan (to limit the rate at which
reinforcements can arrive), the ROK's mobile forces, or Pyongtaek/Camp Humphreys, south ofSeoul.
Use Case Consequences
Perhaps as in some of the cases above—that is, eager to see the United States weakened by(another) war but unwilling to enter one themselves—China and Russia accept US assurancesthat the US goal in using nuclear weapons is limited to reducing/removing further DPRK nuclear
weapons threats, and removing DPRK leadership, but China and Russia require a deal in advancefor significant roles in the governance of a defeated DPRK, perhaps through the UNSC. China
and/or Russia might alternatively (or in addition) insist on the survival of the Kim regime as aquid pro quo to staying out of the conflict and consider that to be fulfillment of their obligations(formal or otherwise) for defense of the DPRK.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Although recent military doctrine suggests that the United States would tend to rely on precisionguided conventional weapons to repel a conventional DPRK attack, the United States would
need mobilization and deployment of those weapons, and of the troops trained to use them, to beable to use precise weapons. There could be a number of circumstances—for example, theUnited States being busy fighting wars elsewhere, or having been thrown off guard by a peace
process, in which it would take too long to deploy precision-guided weapons to the Korean
theater (that is, a DPRK attack would be too far advanced by the time the US weapons were
deployed), and thus a nuclear option might look attractive. A major determinant of whether theUnited States would use nuclear weapons in this case would be the personalities and points ofview of US leadership, and, in particular, the US president. If the president is informed andReducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

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supported by advisors and a constituency that is strongly against the use of nuclear weapons, it
lessens the likelihood that the president will direct US forces to use them. If the president is
informed by groups that see value in nuclear weapons use (beyond their deterrence value), andthe president (and his/her advisors) believe that a nuclear war on a distant continent is unlikely to
be of grave concern to their constituency, the odds of US nuclear weapons use in response to asituation like that above would rise.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1623.2.2"US Leadership Hubris"

As the title implies, this use case starts with overconfidence—in both offensive nuclear weapons
and in the systems meant to defend against incoming missiles—on the part of a US president andthe advisors that envelop him or her. In part to divert the electorate from difficult issues at home
and abroad, the president orders an attack on the DPRK’s nuclear and missile systems, but with
only partial success.66 A key element in this case, although also very important in other cases, iswhat group of nuclear weapons advisors have primacy in the White House at the time a nuclear
use (or non-use) decision is made. In his paper prepared for this project, Van Jackson identifies“four schools of thought comprising the US nuclear policy epistemic community” as “Armscontrollers,” “Nuclear traditionalists,” “Nuclear primacists,” and “future-of-war strategists.”67 As
some (not all) of these groups of advisors are associated primarily with the US Democratic or
Republican political parties, the likelihood is high that a president’s party will in large part
determine his or her administration’s nuclear doctrine and play a large role in determining his or
her decisions on nuclear use.
The type of first use described in this case would fall at the intentional end of the spectrum of
reasons for nuclear weapons use.
Triggering Events and First Use
A US president, isolated from experienced advisors and balanced and fact-based
information, comes to believe and/or is convinced that it would be possible to destroy the
DPRK nuclear arsenal (and its related missile inventory) in a set of targeted nuclear
attacks. It is possible that the availability of a new weapon or type of weapon also emboldens
and seduces the president into thinking that an effective attack can be carried out with little
possibility of reprisal. An example might be the under-development (as of 2021) hypersonic(capable of traveling at Mach 6, or about 7000 km/hour) SR-72, an unmanned aircraft that could
be launched from a US base in the region, and reach the DPRK in minutes, and virtually without
warning, or fly from a base on US territory.68 In addition, the president receives and believes
assurance that the missile defense systems it has deployed on US territory and around allies such

66

Alert readers will doubtless recognize that this use case has commonalities with very recent history, including
the story of the worries of the US Joint Chiefs of Staff Chairman, General Mark Milley, regarding the possibility ofthen-President Donald Trump starting a war with China in the waning days of the Trump Administration. See, forexample, Martin Pengelly (2021), “Top general feared Trump would launch nuclear war, Woodward book reports,”
The Guardian, dated September 14, 2021, and available ashttps://www.theguardian.com/books/2021/sep/14/mark-milley-donald-trump-bob-woodward-nuclear-war67
Van Jackson (2021), ibid.
68
See, for example, Dario Leone (2021), “All you need to know about the SR-72 Son of Blackbird: from its
conception to its possible cancellation,” dated April 13 2021, and available as https://theaviationgeekclub.com/allyou-need-to-know-about-the-sr-72-son-of-blackbird-from-its-conception-to-its-possible-cancellation/

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as the ROK and Japan will be effective in eliminating any DPRK weapons that do manage toescape destruction.69
The public justification for the attack by the United States is nominally concern that a muchpublicized DPRK test of a not-before-demonstrated ICBM proves that the DPRK now has theability to threaten US soil, but the underlying rationale for the attack is that the president, having
largely alienated US allies in Northeast Asia, having increasingly involved the United States inan expensive and widely unpopular trade war with China, and facing mounting domestic
problems, is seeking to divert public attention within the United States and bolster his (or her)
popularity by starting a war. Although the attack is preceded by a series of bellicose but nonspecific warnings of military action, the United States does not provide a specific warning ofimpending nuclear attack.
US attacks in this case could be with a combination of conventional precision-guided weapons
first on easy-to-locate targets, such as Yongbyon, but would use penetrating nuclear weapons toremove buried missile silos and/or enrichment facilities or to destroy missiles sequestered in
mountains. The attacks would probably not target Pyongyang, as US leadership (in particular thepresident) is convinced that the destruction of the nuclear arsenal will be enough to get the
DPRK to the bargaining table and wants to avoid contaminating potential future real estate
investments. This case assumes that virtually all of the attacks on known nuclear weapons anddelivery system facilities are successful, but that not all DPRK warheads are destroyed, as someare hidden both deep and in otherwise unremarkable locations, such a railway tunnel through amountain, perhaps close to the Chinese border where the United States would be reluctant to
attack even if the location was known to contain a missile. The DPRK may also use deception to
make the United States believe it knows where its missiles are, such as providing harder-to-hideliquid-fueled missiles with camouflage that it knows US technical means can see through, while
hiding solid-fueled missiles in locations more impenetrable to US or international detection.
How the Conflict Evolves
The DPRK, which assumes that the US attack has been carried out with the tacit permission of
the ROK and Japan, though the ROK and/or Japan might not know about it in advance,
counterattacks with an assault on the ROK and/or possibly Japan. Although the US attack has
rendered most of the DPRK’s delivery systems for nuclear warheads disabled or inaccessible due
to fallout, the DPRK has sequestered several nuclear warheads in hard-to-find locations, possibly

69

See, for example, David Wright (2022), The Role of Missile Defense in North-East Asia, paper prepared for the
Reducing the Risk of Nuclear Weapons Use in Northeast Asia project (ibid). Some of the key lessons of studies ofcurrent missile defense systems are that those systems may not be as capable of intercepting incoming missiles
under real-world circumstances as they are advertised to be, may not have been thoroughly tested under field
conditions, may only work on certain types and trajectories of incoming missiles, and may be relatively easily
defeated by countermeasures incoming missiles could employ, such as tumbling or twisting flight, or the use ofmultiple munitions or warheads. In addition, although an adversaries’ knowledge of the presence of missile defense
systems may cause it to think twice about attacking, it may also cause a change in attack strategy or induce the useof multiple missiles to overcome the potential effectiveness of and ABM system.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 164either deep underground and/or surrounded by civilian dwellings, and, while appearing to beconsidering suing for peace, marshals these remaining weapons for a counterattack.
For its counterattack, strike groups of DPRK Special Forces rig remaining warheads with remotedetonators70 and bring them by sea to a major ROK (or Japanese?) port. Conveyance could be in
one of the many small DPRK submarines, or in, for example, a stolen ROK or Japanese fishingboat or in a DPRK vessel disguised as such. It is possible that this sort of attack would be
unlikely to succeed due to vigilant and well-organized ROK coastal defenses, but one or moregroups might slip through. Japan, with a much longer coastline facing the DPRK, might beharder to defend against such attacks. Land-based attacks on the ROK, through tunnels under the
DMZ, are also possible, although presumably a US nuclear attack on the DPRK would place
DMZ patrols on high alert, unless they were forced to retreat due to cross-border fallout from US
attacks. Fallout might also affect a cross-border DPRK incursion, but a DPRK attack squadmight be less concerned about radiation exposure.
The target of the counterattack could be a place where the NUDET would damage multiple
important infrastructure installations, such as LNG (liquified) storage facilities, roads to a major
city, or airports. For example, a weapon hidden among small ships/boats at Incheon, could,
depending on the size of the weapons, damage the road/bridge to ICN and maybe the airport
itself, nearby oil tankage and LNG import facilities, the Port of Incheon itself, the city of
Incheon, coal storage, a small ROK naval facility, and much more, all of which are within a 10km radius.71 If much or all of that were destroyed or rendered inoperable, it might significantly
cripple the ROK economy.
An alternative (or perhaps concurrent) type of counterattack might be for a DPRK Special Forces
team to mount a similar attack on Japanese infrastructure, including energy and port facilities
and/or a nuclear power plant near Tokyo. In this case, the DPRK would be seeking to force
Japan to use its Self Defense Forces to deal first with the resulting crises in its own country(which, given the experience of the Fukushima reactor disaster of 2011, could take months or
years) before aiding the US/ROK in a war on the Korean peninsula and could serve to divide thecoalition arrayed against the DPRKUse Case Consequences
If it sees the US attack as "unprovoked," China will possibly feel obliged to come to the aid of
the DPRK, though probably with conventional weapons designed to keep US and ROK
conventional forces south of the DMZ. Russia probably stays out of the fray, waiting to see what
will happen, and happy to see adversaries otherwise engaged. If a DPRK counterattack on the
ROK or Japan did indeed occur, it seems likely, however, that one or both of Japan and the ROK
would demand that the US follow up with an attack on DPRK leadership, which might cause
China to attack the United States, leading to a full-scale nuclear conflict.

70

Note that it is possible that this type of bomb could be detonated either remotely or via a suicide mission by
DPRK Special Forces.
71
For example, a location along the docks at Incheon centered at latitude and longitude coordinates 37.446332,
126.607192.

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Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Perhaps more than some of the other use cases above, this particular use case offers many
uncertainties, or decision points, in which miscalculation (or the wrong decision) could easily
cause the conflict to spread to a nuclear conflagration. If the US launch was from a submarine,for example, and not communicated in advance to Chinese and Russian military leaders, it ispossible that one or both of those powers might mistake the US launch for an attack on theirterritory and trigger launches of nuclear ballistic missiles from their own submarines on US
bases in the region and/or the US mainland itself. Those launches, in turn, would likely spur theUnited States to counterattack China and/or Russia with ICBMs and cause the launch of ICBMSfrom China and/or Russia on the US mainland and possibly US allies. Armageddon would be theresult of such an exchange.
Key policy lessons from this case might include making sure that nations where a single leader is(or can be) virtually omnipotent have procedures for war authorization that force inclusion ofindividuals outside of the leader’s inner circle, and the need to consult with both allies and notdirectly-involved adversaries to limit opportunities for misunderstanding of intent (although evensuch consultations may be inadequate absent trust). In addition, leaders should receive accurate
information about the effectiveness of weapons systems, particularly missile defense systems,
against adversaries’ offensive weapons, so as not to be deluded by the potential of such systems
to solve problems that should be addressed through diplomacy.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1663.2.3"Response to DPRK Proliferation"

In this use case, it is not the DPRK’s own direct provocations that spurs the United States to use
nuclear weapons on the DPRK, but rather the results of DPRK proliferation of nuclear
technologies and/or nuclear materials. This use case would be categorized somewhere in the
middle of the unintentional to intentional range of first use because the United States is using
nuclear weapons in response to perceptions of proliferation rather than to gain militaryadvantage.
Triggering Events and First Use
The DPRK proliferates nuclear technologies to other countries or to non-state actors, such as
Middle Eastern jihadists, who use their weapons on US assets. The DPRK’s motivations inproliferating nuclear weapons include earning money to support its weapons programs, testing(through others) the technologies it develops and sells, and creating a degree of disorder andconfusion regionally or globally in order to induce its adversaries to offer concessions.72 The
proliferation could result in a nuclear detonation in the Middle East, or the deployment of a dirty
bomb in a US-allied country (or in the United States itself), or a threatened use of a nuclear
weapon by a state or non-state actor that the United States and its allies foil but trace to a
DPRK origin. Stating that the DPRK has "crossed a red line," the United States threatens
a nuclear attack on the DPRK unless the DPRK agrees to immediate denuclearization andto dismantle its proliferation networks. When the DPRK responds with more strident
rhetoric, the United States attacks Yongbyon and other known nuclear-infrastructure
targets in the DPRK but does not attack DPRK leadership directly.
US attacks could be with a combination of conventional weapons first and/or use of penetrating
weapons to remove buried missile silos and/or enrichment facilities or missiles sequestered in
mountains.
How the Conflict Evolves
The DPRK could reply with conventional weapons, for example, targeting US bases, but it mightalso assume that an attack on leadership is imminent and thus launch a nuclear strike.
The DPRK strike could be on a US military target in the ROK, possibly in the Seoul area. Or, if
the DPRK considers fallout floating north—such as with prevailing summer wind patterns—tobe a concern, an attack on a southern ROK city or on Sejong might be considered. In either case,the intention would be to inflict heavy damage and sue for peace. This assumes that one or more
short/medium range missiles, which would be relatively easy to hide, escape US actions.

72

See, for example, Toby Dalton (2021), “The Most Urgent North Korean Nuclear Threat Isn’t What You Think,”
Commentary, Carnegie Endowment for International Peace, dated April 15, 2021, and available ashttps://carnegieendowment.org/2021/04/15/most-urgent-north-korean-nuclear-threat-isn-t-what-you-think-pub84335

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If DPRK ICBMs are sufficiently reliable (or maybe even if not) AND if they survive what would
probably be an intense US effort to destroy them, retaliation with an ICBM on the United States,
or with a medium-range missile on Japan, might also be considered by the DPRK.
Use Case Consequences
As in cases above, if it sees the US attack as "unprovoked," China will possibly feel obliged tocome to the aid of the DPRK, though probably with conventional weapons designed to keep US
and ROK conventional forces south of the DMZ. If the US attacks are aimed (or stray) too far
north in the DPRK, or bombers or missiles overfly or come too close to Chinese territory, China
may believe that an attack on their territory is underway or imminent and may launch a
retaliatory nuclear attack. Russia again probably stays out of the fray, waiting to see what will
happen and happy to see adversaries otherwise engaged.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Would the ROK condone such as response, or would it ask the United States to hold off on
retaliation for proliferation? A variant of this case might be one in which the United States isunable to determine who carried out the nuclear (or dirty bomb) attack, but it uses nuclear
forensics to trace the origin of the nuclear material to the DPRK, and concludes, perhaps
erroneously, the DPRK has in fact carried out the attack and thus responds, 9/11-style, with acounterattack of its own.73

73

This is something to check, but it seems an open question whether, if the DPRK does proliferate nuclear
weapons technologies, it would also sell some of its fissile materials for another state or a non-state actor to use in
their own weapons. Presumably, nuclear forensics would look to identify the source of the fissile material, but it’s
possible that material could be (or could have been, years ago) smuggled out or Russia, the United States, Europe,
or Japan, from stocks of reprocessed plutonium or weapons-grade uranium. If so, would nuclear forensics tracethat material to the DPRK? Would the isotopic signature from a nuclear detonation or a dirty bomb be enough toboth trace the origin of the nuclear material and the weapons technology used?

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1683.2.4“Tripped at the Finish Line”

In this use case, what appears to be a major deescalating win for the international community on
the Korean Peninsula goes awry at the last minute, as negotiations between the DPRK and theUnited States/ROK break down over an unexpected event, causing the DPRK to redouble its
threat to target the ROK with nuclear weapons, and the United States, mistaking DPRK
brinksmanship for actual intent, to launch a pre-emptive nuclear strike. This use case would be
categorized closer to the unintentional end of the unintentional to intentional spectrum of firstuse.
Triggering Events and First Use
Early in 2022, the Biden Administration in the United States begins the process of re-engaging
with the DPRK, and a well-behind-the-scenes diplomatic effort gradually brings the DPRK to thenegotiating table. In May, President Biden himself flies to Pyongyang to meet Chairman Kim
Jong Un, with an Air Force C-17 cargo plane in tow packed with emergency food rations andmedicines for humanitarian use in the DPRK. Their summit goes well and sets a framework forthe beginning of talks between the nations. In late 2022 a third-party, cooperative threat
reduction (CTR) project is launched emphasizing pilot application and capacity building inenergy efficiency and renewable energy in the DPRK, with tacit approval of the governments(ROK, United States, EU) involved and perhaps some indirect government funding, but carriedout by a coalition of non-governmental agencies, government think-tanks, academics, and others.
This project is resoundingly successful in providing images of cooperation for both DPRK and
US leaders and leads to more cooperation on energy sector activities in the DPRK, accompaniedin parallel by progress on nuclear weapons issues, including the DPRK freezing its nuclear
weapons work and admitting IAEA (International Atomic Energy Agency) inspectors into thecountry to view some (but perhaps not all) nuclear-related sites.
Productive negotiations and gradual opening of the DPRK economy, with lifting of UNSC
sanctions, continue through the re-election of Biden in 2024 (or maybe the election of President
Harris?) and for the ensuing four years, with high-profile engagement such as the rebuilding of arail line across the DMZ between Pyongyang and Seoul, the use of the rail line to facilitate visits
between separated families, further cooperation on energy and on DPRK minerals production,and other initiatives. By 2028, the DPRK is ready to start negotiating on actual removal of some(not all) of its weapons in exchange for security promises by the United States. But then one of
two things happen. Either:
1. A new US administration with a more ideological bent takes office and comes into its firstmeeting with the DPRK delegation with additional demands not consistent with the steps thatthe parties had been following. This could be, for example, a return to a demand for
immediate and full DPRK “denuclearization,” or a demand that the DPRK immediately
adopt Western levels of human rights guarantees. OR
2. An unexpected event completely derails negotiations. An example of such an event might be
if Kim Yo-jong, who has been growing in power in the DPRK and by then has been fully
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69deputized by her brother Kim Jong Un to oversee negotiations with the United State/ROK,74
is assassinated in Seoul during a visit to her ROK counterpart by what appears to be a soldier
in an ROK army or USFK uniform, but is actually an agent of a right-wing ROK or US
group in disguise, or perhaps just an individual with mental health issues who has been
indoctrinated into a terrorist group.
In either case, the DPRK accuses the United States of duplicity in negotiations (and, in the latter
case, murder), expels IAEA inspectors via the rail line between Seoul and Pyongyang, blows up
the portion of the rail line in the DMZ, and overtly begins to set up and fuel a set of nuclear
missiles, as well as placing its conventional forces closer to the DMZ and massively increasing
exercise tempos. Mistaking this brinkmanship on the part of the DPRK (which is looking
for an abject apology from the United States/ROK) for an actual intention to attack, theUnited States first threatens attack, then, faced with a strident reply from the DPRK
(which thinks the United States is probably bluffing) attacks the missiles it can see withconventional PGM and deeply protected locations where it believes warheads are storedwith bunker-busting nuclear-tipped missiles, although it does not (yet) target DPRK
leadership.
How the Conflict Evolves
The DPRK responds with a conventional bombardment of Seoul and uses some of its remaining
weapons (hidden in remote railway tunnels) to target US bases in the ROK, including those nearSeoul and the resupply bases in the southern part of the ROK. The United States responds, and afull-scale war on the Peninsula ensues.
Use Case Consequences
As in many of the cases above, China and Russian forces go on high alert and mass near the
DPRK border but do not get involved in the conflict. If Japan sends troops to aid the UnitedStates/ROK in the war, which it might, the DPRK may respond with a nuclear strike on a
populated area of Japan with a nuclear weapon, or it may try to target the US base on Okinawa—
but the latter is a smaller target. The war results in the near-complete destruction of the Korean
Peninsula, possible damage in Japan, and possible fallout damage in Northeast China, whichmight or might not bring China itself into the war.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Major uncertainties in this case include how the DPRK might respond to the United States
throwing a “curveball” at an advanced point in negotiations, which might have more to do withhow secure DPRK leadership feels at home than what the United States actually says and does.
In addition, there is a question of whether the US delegation would be able to identify DPRK
brinkmanship for what it is and would be able to defuse the situation (or rather, whether the74

Such a designation does not seem, as of this writing, outlandish. See, for example, Laura Bicker (2021), “Kim Yojong says North Korea open to ending war if conditions met,” BBC News, dated September 24, 2021, and available
as https://www.bbc.com/news/world-asia-58675703

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individuals in or advising the delegation who DID recognize the situation and have solutions thatwould actually be listened to.
Key policy lessons here would be to work to stay the course of negotiations even in times thatlook desperate and to be ready to give the other side what they need to look good to their own
constituency.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1713.2.5"A Promise is a Promise"

As noted earlier in this Report, the United States’ extension of nuclear deterrence to theterritories of Japan, the ROK, and (perhaps less formally) Taiwan are key elements in the
security systems and doctrines of those states. In the three variants of the case described below, it
is keeping the promise of the “nuclear umbrella” that drives the United States to use nuclear
weapons first. This type of use case appears to have elements of both intentional andunintentional nuclear first use, as the United States is drawn reluctantly into nuclear use, without
originally intending to attack the DPRK, but does so as a direct outgrowth of its promises, that is,
to re-establish deterrence.
Triggering Events and First Use
Variant 1: Following a period of worsening DPRK relations with Japan, potentially exacerbatedby more strident leadership in Japan, and further economic decline in the DPRK due tosanctions, the DPRK launches a nuclear HEMP (High Altitude Electromagnetic Pulse) shot overTokyo that causes major infrastructure damage through its effects on electronics. Note that inthis case we consider the DPRK HEMP attack, though it is in fact a use of a nuclear weapon, tobe a “triggering event,” not a “first use,” because it is not a detonation on or near the surface ofthe earth. We recognize, however, that this could be considered a somewhat artificial distinction.
Fearing a DPRK attack on its populations, either conventional or nuclear, while its sensor,
missile defense, and other systems are offline, Japan asks the United States to respond with
nuclear weapons, and the United States reluctantly agrees, possibly with arguments in one
or both directions (for and against attack) from the ROK. The United States considers
offering the DPRK an ultimatum before using nuclear weapons on the DPRK, but reasons thatthe DPRK leadership must be removed to simultaneously resolve the problem and assure that
there will be no nuclear counterattacks on the ROK, Japan, or US territory (although thatassurance may not be particularly solid), and thus must strike without first threatening nuclear
use in order not to give DPRK leadership more time to go deep underground or to initiate a strikeof their own. A sub-variant of this case could be one in which the triggering event is a
widespread cyber-attack traced to DPRK state-sponsored hackers. In this case the cyber-attack
might shut down electricity supplies, water supplies, and/or gas or oil pipelines, and/or disrupt
official and civilian transportation and communications channels sufficiently that, as above,
Japan finds and fears itself vulnerable due to the widespread disruption, fears a DPRK militaryattack, and presses the United States to respond.
Variant 2: This variant follows the same pattern as above, but the ROK is the focus. Following aperiod of worsening DPRK relations with the ROK and the United States, potentiallyexacerbated by more strident leadership in the ROK and/or the United States, and further
economic decline in the DPRK due to sanctions, the DPRK launches a nuclear HEMP shot overthe DMZ that causes major infrastructure damage in the ROK and significantly degrades
ROK/USFK communications and control capabilities. Fearing a DPRK assault on its
populations, including a massive ground assault, while its sensor, missile defense, and othersystems are offline, the ROK asks the United States to respond with nuclear weapons, andthe United States reluctantly agrees. The United States reasons that the DPRK leadership must
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be removed to simultaneously resolve the problem and assure that there will be no nuclear
counterattacks on the ROK, Japan, or US territory (although that assurance may not be
particularly solid). A cyber-attack by the DPRK on ROK infrastructure could, as in Variant 1,
result in the ROK pleading for US nuclear assistance.
Variant 3: This variant largely follows the narrative of Variant 1, but in this case the DPRK
uses chemical and/or biological weapons, delivered either though a Special Forces attack or by
missiles each designed to distribute multiple “charges” of these weapons over a large area. Due
to worsening relations with Japan, potentially exacerbated by more strident leadership in Japan,
further economic decline in the DPRK due to sanctions and other challenges, and possibly as areaction to the beginnings of dissent in the general DPRK population, the DPRK leadership
attacks, or possibly is believed to have attacked, Japan and/or the ROK with chemical and/or
biological weapons. Fearing continued DPRK stealth attacks on its populations, Japan asks theUnited States to respond with nuclear weapons, and the United States reluctantly agrees, likely
with arguments in one or both directions (for and against) from the ROK. (DPRK chemical or
biological weapons attacks on the ROK could alternatively be the trigger in this case, withcorresponding negative or positive reactions from Japan). As above, the United States reasonsthat the DPRK leadership must be removed to simultaneously resolve the problem and assurethat there will be no nuclear counterattacks on the ROK, Japan, or US territory (although thatassurance may not be particularly solid).
How the Conflict Evolves
With its leadership threatened, and possibly attacked, but unsuccessfully, the DPRK respondswith a nuclear weapons attack. The DPRK attack is designed to inflict pain, possibly on the US
mainland, if its ICBMs survive US preemptive strikes, and possibly in Japan or (perhaps lesslikely, in this case) Seoul. The United States concludes that the DPRK leadership has probably
moved into deep underground, thus requiring the use of nuclear weapons to effectively reach theleaders. Bunkers in Pyongyang and other locations indicated by US and ROK intelligence as
likely hiding places—perhaps in Wonsan, on the DPRK’s East Coast, where the Kim family
reportedly goes on holidays—are identified and targeted. The United States uses a new (50 kt)
penetrating weapon to retaliate against DPRK leadership and possibly buried missile systems or
those concealed in mountain tunnels.
Use Case Consequences
The HEMP shot over Japan, which probably affects some Chinese infrastructure as well, allows
China to categorize the US attack as "provoked," and thus it is not obliged to come to the aid of
the DPRK, though it would probably extract some sort of deal as to governance of the DPRK
and/or the degree of northern deployment of US troops on the Peninsula, possibly through the
UNSC. Russia watches what happens carefully, and probably deploys submarines to key
positions around the Peninsula but does not directly intervene.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Although this use case offers the possibility that some areas of the globe could be spared—
assuming that Russia and China stay out of the conflict—that is certainly not a given, particularly
if, for example, US attacks on the DPRK from ships, planes, or submarines are mistaken by
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automated security systems as potential attacks on Russia, and/or China. And even if the ROK is
not targeted directly by the DPRK, it seems likely that some fallout from attacks on the DPRK
will make areas of the ROK unusable, and the ROK, as well as China and possibly Russia, will
face a major refugee crisis as DPRK citizens who have escaped the bombing flow toward andacross borders.
Another uncertainty is whether the use of chemical and/or biological munitions in Variant 3 issufficiently different, from the point of view of Japan (or the ROK), to an attack by a HEMP thatit causes either party to either more or less forcefully argue for a US nuclear response.
Potential policy lessons include:•

Build redundant, HEMP-resistant communications infrastructure/procedures for use in
the event of a HEMP attack, particularly for critical communications equipment,
including for both civilian and military leadership.

•

Discuss and reach agreement with allies on what types of attacks would and would notnecessitate activation of nuclear reprisals under nuclear umbrella arrangements.

•

Work to make sure that DPRK conditions do not reach a level of desperation sufficient tocause the types of triggering events above to happen.

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3.3 China as First User
A decade ago, most observers of China would probably have rated just about any case in which
China was the first user of nuclear weapons in a conflict to be highly implausible. Since then,however, China’s military build-up, including of its naval and missile forces (including, recently,
what appear to be hundreds of added ICBM silos), appear to indicate a greater emphasis by
China on its nuclear deterrence. Still, as the global manufacturing and trade powerhouse, China
would have much to lose in entering, and certainly in starting, a nuclear conflict.
3.3.1"Not Going Well in Taiwan"

Most of the plausible cases in which China might be a first user of nuclear weapons involve its
claims on Taiwan, or are arguably associated with its position on sovereignty over Taiwan,
including conflicts at sea related to its projection of naval force and territorial claims. As such,there are probably a number of different use cases that could be devised in which China ends up
a first user of nuclear weapons, and a much greater number of cases in which it focuses on theuse of its conventional forces (in part due to wishing to avoid nuclear counterattacks on its own
territory, as well to avoid attacks on Taiwan, which it considers its own territory). One
illustration of a case where China is the first user of nuclear weapons is provided below. This
nuclear use can probably be considered midway between unintended and intended on theintentionality continuum due to being in response to conventional attacks by a strong group ofantagonists.
Triggering Events and First Use
A more assertively international, pro-independence government takes office in Taiwan, andmassive protests erupt in Hong Kong over PRC control of the SAR (Special Administrative
Region). Protests in Hong Kong start to swing public opinion on the Chinese mainland, worrying
the Chinese government. With the United States re-engaged in Middle Eastern conflicts in
Afghanistan and Iran, China attacks Taiwan's perimeter defenses, but suffers significant
setbacks, including the loss of airfields in Fujian Province75 and the loss of significant naval
ships, when the United States and its allies, including forces from the ROK and Japan, come tothe aid of Taiwan.76 Worried about further involvement of US forces in the Taiwan conflict,
China first threatens, then when threats appear to have little effect, and convinced thatconventional defeat is imminent, attacks US bases in the region, and probably US ships atsea, with one or more nuclear weapons. Some of the issues that the allies and adversaries in

75

See, for example, Keoni Everington (2021), “China expands its 2 air force bases closest to Taiwan: PLA expanding
its Longtian and Huian air force bases in Fujian Province”, Taiwan News, dated 2021/03/08, available ashttps://www.taiwannews.com.tw/en/news/4145038
76
Variants of this type of use case involving China are provided in, for example, Mike Sweeny (2021), Why a
Taiwan Conflict Could Go Nuclear, Defense Priorities, dated March, 2021, and available ashttps://static1.squarespace.com/static/56a146abb204d5878d6f125a/t/603e4a8572604252495449c0/1614695047
482/DEFP_Why_a_Taiwan_conflict_could_go_nuclear.pdf

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75this use case grapple with are related to the counterforce issues discussed in a paper prepared forthis project by Ian Bowers.77
How the Conflict Evolves
The United States responds with conventional missile attacks on a number of military targets in
China (and at sea) that threaten Taiwan, with nuclear attacks focusing on remote, hardened
military targets away from population centers to forestall China's use of ICBMs on either Taiwan
or on the United States itself. Examples of remote, hardened targets for US nuclear missiles
might include the recently-built nuclear missile bases in Xinyang Province and in Gansu
province.78 Given an attack on Okinawa, the United States would be expected to consult withJapan regarding a counterattack on China.
Use Case Consequences
If this use case somehow (see below) remains a limited conflict, Russia, happy to see its rival theUnited States (and part-time rival China) engaged and likely weakened, remains on the sidelines
during the conflict, but probably takes the opportunity, after the conflict winds down, to forge
stronger military ties with China.
It seems implausible, however, that China would tolerate a nuclear attack on its territory without
launching an attack on US territory, which would probably have to be met with a counterattackfrom the Unite States. It seems unlikely that that the exchange of weapons would end without
scores of weapons being exchanged, which would amount to global nuclear war. The UnitedStates, through NATO, might ask European nuclear powers (United Kingdom and France) torespond to China as well, which would involve the EU in the conflict. Whether, at that point,
Russia would also remain outside the conflict is hard to predict. This case thus appears hard toconceive of as ending in anything but near-global nuclear war, with catastrophic and long-lastingrepercussions for survival of human society as we know it, as well as on the natural processes
that we depend on.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
This case thus appears hard to conceive of as ending in anything but near-global nuclear war,with catastrophic and long-lasting repercussions for survival of human society as we know it, as
well as on the biosphere and other natural processes that support life on earth.
Surrounded on both of its major land borders by areas affected by nuclear weapons, and possibly
affected by fallout, from those areas and/or from Japan, it is unclear what the DPRK would do in77

Ian Bowers (2021), Counterforce Dilemmas and the Risk of Nuclear War in East Asia, paper prepared for the
Reducing the Risk of Nuclear Weapons Use in Northeast Asia project, October 2021 (publication forthcoming).
78
See, for example, Al Jazeera (2021), “China is building a 2nd base for nuclear missiles, say analysts,” dated 28
July, 20201, and available as https://www.aljazeera.com/news/2021/7/28/china-is-building-a-second-missile-silofield-say-us-researchers; and Joby Warrick (2021), “China is building more than 100 new missile silos in its western
desert, analysts say,” Washington Post, dated June 30, 2021, and available ashttps://www.washingtonpost.com/national-security/china-nuclear-missile-silos/2021/06/30/0fa8debc-d9c2-11ebbb9e-70fda8c37057_story.html

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 176this case. It seems unlikely that it would get involved in the war itself, and the survival of its
people, whose current lack of food and (especially) oil would be compounded by isolation
caused by ongoing wars to the North and South.

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3.4 Russia as First User
Most (but not all) of Russia’s economic and military assets and the vast bulk of its population arelocated in the western part of the country, many thousands of kilometers from Northeast Asia.
The Russian Far East, the vast and lightly populated-—about 8 million people in a region nearly
the size of the contiguous United States, and 40 percent larger than the EU–part of Russia that iswithin Northeast Asia, is largely a land in which economic opportunities (such as energy
exports) depend on cooperation with neighbors. Thus, Russia has arguably every reason to avoid
entering a nuclear war in Northeast Asia. As such, few use cases come to mind in which Russia
would be a first user in a nuclear conflict in the region in general, and on the Korean peninsula inparticular. Those that do come to mind tend to be associated with either mischaracterization ofanother actor’s nuclear intentions, command and control errors, and/or or conflict at sea
regarding Russia’s military assets, as posited in the use case below. Due to their elements ofcommand-and-control and/or technical failure, these nuclear weapons uses can be categorized as
being in the “accidents in peacetime” category described by Davis and Bennett, or, if these
Russian nuclear uses happen during a period when war is arguably not far off, at least firmly at
the unintentional use end of the spectrum.
3.4.1“Threats to Russian SSBN Bastions”

In this use case, a Russian submarine commander finds himself or herself confused by what isperceived to be a nuclear attack but is actually a weapons test or an exercise, and, unable tocorroborate the situation with Pacific Fleet command, follows existing rules of engagement(ROE) and fires nuclear weapons on a US base in the region.
Triggering Events and First Use
A renewal—or rather, heating up—of the simmering dispute over the islands at the north end of
the Japanese archipelago results in a significant increase in patrols in the Sea of Japan and nearby
waters by Russian submarines from their base near Vladivostok. During one of those patrols, thecrew of a Russian nuclear powered (and nuclear-armed) submarine finds itself in a situation
where it believes a nuclear attack on its base has or will imminently occur, and, unable tocorroborate that belief by communication with commanders onshore or in the Pacific Fleet, thesub commander follows his or her standing orders and fires nuclear-tipped ballistic missiles.
There are several possibilities, albeit some of them straining plausibility, for why the crew of thesubmarine might believe a nuclear attack is underway. It could find itself in the middle of an
ongoing US/ROK joint exercise involving ships and submarines, and, not having been briefed on
the exercise, assumes that it is an attack that is headed toward Russian territory. It might mistakea DPRK missile test—or, in fact, a “demonstration” DPRK nuclear detonation at sea—that
occurs in the vicinity of the Russian sub to be an attack on the sub itself or on a nearby Russiancarrier group, or on its base in Vladivostok. It could be that by the time of the incident, continued
friction and mistrust in the relationship between Russia and the United States have increased thelevel of military alert among all Russian military forces. In any case, lacking corroboration,
but following orders during a period of heightened alert, the Russian sub fires a sortie of
nuclear-tipped ballistic missiles on their designated target, which in this case is the US
military base in Okinawa.
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How the Conflict Evolves
The United States, perhaps encouraged by Japan, launches an attack in reprisal on the Russian
Pacific Fleet headquarters (and nearby airfields) in and near Vladivostok, and on the Kamchatka
Peninsula. These attacks destroy the airfields there and much of the land-based fleet
infrastructure, but most of the submarines and ships normally based there are at sea, and thus
survive the attack. In response, Russian submarines and ships fire conventional and nuclear
missiles on other US bases in the region, including navy bases and airfields in the ROK.
Use Case Consequences
Assuming, as above, that this incident occurs during a period of already heightened tensions
between the United States and Russia, it is difficult to see the nuclear war being confined to
Northeast Asia, at least without extraordinary and virtually instant communications anddiplomacy between US and Russian leaders. Absent those communications, it seems likely that
ICBMs will be launched between the United States and Russia. China might well mistake missile
launches by the United States to be aimed at its territory and thus launch its own ICBMs. The
result would be a nuclear calamity involving much of the northern hemisphere immediately, withthe rests of the hemisphere affected eventually though the fallout and resulting environmental
damages and/or through global economic collapse.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
A key uncertainty in this use case is how the crew of a Russian submarine could be expected toreact in a situation such as that outlined above, and whether its standing rules of engagement,
absent communications with its command, would include launching on a US base even without
firm evidence that the United States was behind the perceived attack.
Relatedly, a policy lesson from this case would be to raise awareness within the militaries
operating in the region as to how adversaries (and, for that matter, allies) are likely to interpret
various situations and perceived actions, as well as to maintain military-to-militarycommunications at the highest levels, even during times of heightened tensions. If it is found that
there are standing orders that could easily invoked in a situation such as this, where an exercise
or test is mistaken for an attack, those standing orders should be modified so that mistaken
launches of nuclear weapons do not happen.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1793.4.2“Dead Hand Error”

The capabilities of artificial intelligence (AI) in both the civilian and military spheres havegrown rapidly in recent decades, and development and deployment of AI systems have grownexponentially. Nuclear weapons states are increasingly turning to AI to aid in nuclear commandand control. Russia—and previously, the Soviet Union—have been one of the leaders in
deploying AI in the context of nuclear weapons control, starting in the 1980s with a systemcalled the “Dead Hand” part of a project called “Perimeter,” which would enable the launch of
nuclear weapons in the event of a Soviet (now Russian) leadership decapitation.79 The following
use case posits an accidental use of nuclear weapons when the AI system relied upon (in part, atleast) by Russia to launch a retaliatory nuclear strike becomes convinced that enemy weapons areincoming and launches nuclear weapons in response. Note that although this use case identifies
Russia as the accidental first user, related risks of accidental launch exist to at least some degreein the nuclear command, control, and communications systems of at least the United States andChina.80 By the late 2020s or 2030, the penetration of AI into these systems in all states is likely
to be greater than today.
Triggering Events and First Use
The “Dead Hand Error” nuclear use case occurs when automated elements of Russia’s nuclear
weapons control system is “fooled” by a combination of events. First, a “solar storm” whose
impacts are most severe in the Russian Far East temporarily blinds some Russian early warningradar facilities and knocks out key communications links. At the same time, a space launch takes
place at the Naro Space Center in the southern part of the ROK. The rocket launched by the
ROK resembles a nuclear-tipped missile, and its trajectory is such that the remaining Russian
radar facilities mistake the rocket for a nuclear-tipped missile launched from a US base in the
ROK toward the submarine bases around the Sea of Okhotsk. The launch had been moved up at
the last minute to take advantage of a favorable weather window, and though an announcementof the launch was relayed, as per protocol, to all of the states in the region, communications
interruptions caused by the solar storm mean the message was not received by the Russian
nuclear command. Communications interruptions by the solar storm also trigger responsibility
for Russian nuclear missile launches to devolve to the AI system, and before human operators
can intervene, several missiles have been launched from Russia Pacific Fleet assets toward US
79

See, for example, Valery E. Yarynich (2003), Nuclear Command, Control Cooperation, published by the Center for
Defense Information, dated May 2003, and accessible athttps://archive.org/details/c3nuclearcommand00vale/mode/2up
80
Little is known about the DPRK’s nuclear command, control, and communications (NC3) system, but it is thoughtthat little or no automation is currently used in the DPRK’s NC3. See Myeongguk Cheon (2019), DPRK’S NC3
System, NAPSNet Special Reports, dated June 06, 2019, and available as https://nautilus.org/napsnet/napsnetspecial-reports/dprks-nc3-system/. Descriptions of China’s efforts to incorporate AI into their nuclear commandand control systems can be found in Fiona Cunningham (2019), Nuclear Command, Control, and Communications
Systems of the People’s Republic of China", NAPSNet Special Reports, dated July 18, 2019, and available ashttps://nautilus.org/napsnet/napsnet-special-reports/nuclear-command-control-and-communications-systems-ofthe-peoples-republic-of-china/; and Elsa B. Kania (2019), Emerging Technologies, Emerging Challenges—The
Potential Employment of New Technologies in Future PLA NC3", NAPSNet Special Reports, dated September 05,
2019, and available as https://nautilus.org/napsnet/napsnet-special-reports/emerging-technologies-in-future-planuclear-command-control-and-communications/

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80bases in the ROK. Although Russian human operators are able to reestablish communications
and control in time to intervene to stop imminent launches toward US bases in Japan and Guam,the missiles headed toward the ROK cannot be stopped by the Russians. Russian warnings,
issued minutes before the missiles arrive, are not in time to allow the missiles to be intercepted
and missile defense systems in the ROK are either not activated in time or are ineffective in
stopping the missiles, so several major areas within the ROK receive heavy damage from nuclear
detonations.
Although this accidental first use occurs in late 2029, the political setting between the US andRussia is, if anything, worse than in 2022. The Russian military, after having gradually drawn
down troops from the areas surrounding Ukraine in the mid-2020s, are heading back towards theborder in significant numbers as a new, decidedly more pro-Western parliament takes office inthe Ukraine following elections in 2029. Russian oil and gas exports have started to dwindle due
to greenhouse gas emissions reduction measures in Europe, and United States exports continue togrow. As a result, the Russian economy is in the doldrums, and political protests in Russia havecontinued. Nuclear and non-nuclear arms control talks between the United States and Russia
have gone nowhere, and China has refused to join the talks. A new US president is elected who
favors a generally more hawkish, less trusting approach to Russia than had been the case in thepreceding years.
How the Conflict Evolves
The initial inclinations of the US military and the new US president are to assume that Russia’s
assertion that the launch was in error are a tactic to constrain the US response. That is, US
leadership does not initially believe that the launch was an accident. The combination, however,of immediate apologies by the Russian president and every Russian ambassador to the West,
pledges of Russian monetary assistance, though its Reserve Fund, to rebuild the damaged areasof the ROK, and, crucially, a presidential advisor in the United States who is ultimately able topersuade the US president to hold off on a nuclear exchange for 48 hours to gauge the Russians’
sincerity and response, convince US leadership to hold off on reprisal attacks, although the US
nuclear forces go on high alert, causing Chinese nuclear forces to do the same. Within those 48
hours after the launches, round-the-clock intensive diplomacy between Russia and the UnitedStates results in an agreement: all Russian nuclear forces will de-target their weapons, all
Russian nuclear-armed submarines will return to port immediately, and measures that allow theUnited States and its allies to assure that Russian nuclear weapons are not currently targeted andcannot be targeted without warning are to be worked out between the parties. In addition, all
Russian troops in Europe will stand down and return to their barracks. In exchange, the UnitedStates gradually takes its own nuclear weapons off high alert.
The ROK, reeling from the damage caused by the nuclear detonations, monitors the UN
negotiations with Russia, but finds it necessary to use its armed forces to focus on rescue
operations at home. Japan looks on nervously but takes no military action; China does the same.
Europe and other international actors demand the Russia stand down militarily around the world,and Russian social activists, both inside and outside Russia, demand reform of both the Russian
military and political system.

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Use Case Consequences
Paradoxically, the accidental use of nuclear weapons in this case, by providing a vivid
demonstration of the impacts of nuclear weapons to the post WWII generations (meaning almost
all of the earth’s population by 2029), results in a widespread and renewed focus on nuclear
safety and disarmament. Talks on nuclear force reductions, this time including China, resume
and within a few years make significant progress. A gradual shift towards diplomacy rather thanmilitary saber-rattling occurs and continues, even between the United States and China. On the
Korean peninsula, the damage sustained by the ROK is interpreted by the DPRK as anopportunity for diplomacy, and within a few years economic, if not political, integration between
the DPRK and ROK begins, and the DPRK hosts enclaves that become commercial free tradezones near but north of the DMZ for ROK residents displaced by the nuclear blasts and resulting
fallout. The DPRK does not immediately give up its nuclear weapons but agrees to a moratorium
on testing of nuclear devices and missiles, resulting in the international community easing
sanctions and restarting negotiations of nuclear weapons safeguards with the DPRK.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Key uncertainties in this use case are admittedly many, and include (but are not limited to):•

Whether Russian command-and-control systems can indeed be damaged or blinded by asolar storm in the way that the use case suggests;•

Whether a US president would actually be convinced to exercise restraint after such an
accident;•

Whether channels of communication between Russia and the United States could be
ramped up rapidly enough to address the crisis before it spins out of control;•

Whether Russia would really agree to stand down its military as suggested above; and•Whether the DPRK would seize on the opportunity provided by the accident to makeprogress with its neighbors and the international community on security issues on the
Korean peninsula, as opposed to, for example, pressing a military advantage.

Policy lessons from this use case start with ensuring that NC3 systems, whether controlled by AI
or not, provide overrides to automatic launches, and that protocols for communications between
leadership in world capitals be set up to manage the type of launch scenario described above (tothe extent they do not exist already). Also, and very specifically to this case, United Statesassurances, perhaps backed by independent review, that it keeps no nuclear weapons on ROK
territory might allow potential adversaries to safely assume that launches from ROK territory are
non-nuclear, and program automated launch systems to take that distinction into account.

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3.5 Non-Nuclear Weapons States and Non-State Actors as First Users
3.5.1“Broken Promises Leads to Breakout”

The United States provides implicit and explicit promises to use its nuclear weapons in defenseof Japan, the ROK, and other states, should those states be attacked with nuclear weapons. The
cases below posit situations where eroding trust in the United States and internal politics lead theJapan and the ROK, respectively, to “breakout” and develop their own nuclear weapons anddelivery systems.
For the Japan variant, a combination of a shift to non-pacifist, right-wing leadership in Japan,
and leadership in the United States that focuses on other problems, leads Japanese leaders toconclude that the US nuclear umbrella can no longer be trusted to defend Japan from the DPRK
or other potential adversaries, and Japan secretly builds its own nuclear weapons and delivery
systems.81 At some point, sure that a DPRK nuclear attack on Japan is at hand, Japanese leaders
authorize the previously unthinkable and use nuclear weapons on the DPRK.
In the ROK, a right-wing, anti-DPRK administration comes to power amidst a global economic
recession, perhaps due to a resurgence of a COVID-19 variant. With resulting economic
problems at home, and the United States reducing its military footprint in the region for a
combination of cost reasons and to focus on the Middle East or Eastern Europe, and with the
DPRK looking more assertive, well-armed, and disinclined to resume negotiations, ROK hawkspress the argument that the ROK needs nuclear weapons as well.
In the case of both variants, first nuclear use, being premeditated, is likely closer to intentional
than unintentional.
Triggering Events and First Use
Variant 1: The combination of a series of high-profile provocative events by the DPRK inflame
the Japanese public, and a right-wing Japanese administration demands that the United Statespunish the DPRK. The provocations might include a resurgence in kidnappings, and/or DPRK
pirate attacks on fishing boats and ships carrying goods in the Sea of Japan/Korea East Sea,
and/or a series of DPRK test missile launches going over Japanese territory, or possibly a longrange DPRK test missile carrying an actual warhead that overflies Japan and detonates in the
Pacific. When the United States declines to do so—possibly out of fear of the DPRK's ICBMs,
or possibly because of distractions/limitations at home or in other regions, Japan resolves (butnot openly) to develop its own nuclear weapons, which it accomplishes in a matter of months via

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A variant of this case might be that, under intense Japanese lobbying (and beset by other problems at home andabroad), the United States sees merit in allowing Japan to build its own nuclear weapons and relents to agree thatJapan can develop its own nuclear weapons. Such an “official” agreement would be highly likely to havedestabilizing implications for the region, as the ROK would likely demand similar rights, the DPRK would be
incensed, and China and Russia would likely be extremely concerned about Japan’s intentions.

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a clandestine program.82 Japan becomes sufficiently convinced that the DPRK is about to attack
Japanese territory that it decides it must launch a pre-emptive strike against the DPRK, which it
justifies under new security laws. Guided by Korean-Japanese agents who have infiltrated the
DPRK, as well as by advanced remote sensing technology, Japan becomes sufficiently
confident of its ability to locate the DPRK's leadership and nuclear arsenal that it launches
conventional and nuclear (when needed) attacks on both. Japan’s targets therefore include
DPRK missile bases and factories, nuclear production and warhead storage facilities, andleadership homes, offices, and bunkers. Japan's attack would presumably be with guided
missiles.
Variant 2: The combination of a new, anti-DPRK administration in Seoul, perceived UnitedStates lack of attention as the US administration focuses on other parts of the world and on
severe domestic problems, and continuing and increasingly strident DPRK belligerence lead the
ROK to start a clandestine bomb program. The technological and scientific capabilities in the
ROK would allow it to rapidly assemble all of the components needed to assemble nuclear
weapons, as well as missile systems for delivery. Although, unlike Japan, the ROK lacks bothstocks of weapons-grade fissile material and both plutonium reprocessing and uranium
enrichment capacity,83 it does have nearly twenty thousand tonnes of spent fuel in storage
containing on the order of hundreds of tonnes of plutonium, with much the fuel cool enough to
reprocess, and could, conceivably, undertake a clandestine or open-breakout reprocessing
program. And/or the ROK could seek to purchase fissile material on the nuclear black market,
though given the ROK’s standing in the global economy, that would seem like a major politicaland economic risk.
With a nuclear weapon in hand, the ROK becomes convinced, perhaps by DPRK troop
movements, perhaps by DPRK announcements of new nuclear weapons or weapons systems,
that it is about to be attacked by the DPRK, and assurances of support by the United States

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The authors fully recognize that Japanese development of nuclear weapons would be highly antithetical to its
constitution and national post WWII identity. Nonetheless, there are groups in Japan for whom the prospect ofbuilding nuclear weapons is attractive, and Japan possesses the full suite of technologies and raw materials thatwould allow bomb production to rapidly move forward. It is possible that nuclear breakout by a country like Iranwould be a further spur for those voices in Japan agitating to revise its pacifist approach. See, for example, Patrick
Winn (2019), “Japan has plutonium, rockets and rivals. Will it ever build a nuke?” Public Radio International, dated
March 14, 2019, available as https://interactive.pri.org/2019/03/japan-nuclear/index.html. Given the possibility,
however remote, of nuclear breakout by Japan, we feel it is worth considering in this Report to make sure thatpolicy options to prevent it from happening are fully explored.
83
See, for example, Stimson Center (2020), “Fact Sheet: Spent Nuclear Fuel Storage in South Korea,” dated June 2,
2020, and available as https://www.stimson.org/2020/spent-nuclear-fuel-storage-south-korea/). The ROK has
apparently dabbled in uranium enrichment and Pu separation from spent fuel, at least at a small scale, in the
past—and has long proposed to undertake a variant of reprocessing called pyroprocessing, which, if undertaken
for its nuclear reactor program, would leave the ROK a relatively small step away from being able to produce
weapons grade plutonium in large quantities. See respectively, for example, GlobalSecurity.org (undated, but
probably mid-2000s), “Weapons of Mass Destruction (WMD): [ROK] Nuclear Reprocessing,” available ashttps://www.globalsecurity.org/wmd/world/rok/nuclear-reprocessing.htm; and Jungmin Kang and Frank vonHippel (2017), “Reprocessing policy and South Korea’s new government,” Bulletin of the Atomic Scientists, dated,
May 15, 2017, and available as https://thebulletin.org/2017/05/reprocessing-policy-and-south-koreas-newgovernment/

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appear insufficient to allow the ROK to prevail in a conventional war. Confident of its
intelligence north of the DMZ, the ROK therefore resolves a lighting nuclear strike using asmall number of short-range missiles armed with small, low-yield nuclear warheads, with
the intent to remove the DPRK’s military and civilian leadership. Key to this tactic is an ROK
assumption that DPRK citizens are sufficiently primed for regime change and that civilians andthe rank-and-file military will welcome reunification on the ROK’s terms once DPRK leadershipis removed.
How the Conflict Evolves
In both variants, assuming that DPRK leadership and some nuclear capability survives, as seems
likely, as Japan’s or the ROK’s nascent arsenal will be limited and the DPRK’s nuclear sites arelikely to be many, the DPRK counterattacks. Similar to the "US Leadership Hubris" case,depending on what fraction of its nuclear arsenal remained, the DPRK might respond with amedium-range nuclear-tipped missile targeting Japan's leadership, or it could plan a NUDET
delivered by Special Forces that would damage multiple, important infrastructure installations,such as LNG storage facilities, or a nuclear reactor (as in other cases above), or a port near amajor city. The latter type of DPRK counterattack could be using a weapon smuggled across the
DMZ or the Sea of Japan/Korea East Sea in a disguised fishing boat or brought in via submarine.
Use Case Consequences
Whether Japan or the ROK breaks out first, the resulting attack on the DPRK likely fractures the
ROK/Japan relationship, as the ROK would be incensed about nuclear attacks on the Korean
Peninsula by Japan, and Japan would presumably be apoplectic about ROK breakout. In either
case, Japanese or ROK breakout and use of nuclear weapons puts the United States in a quandary
as to what to do. Depending on where the Japanese attacks take place and associated fallout, italso becomes unclear who picks up the pieces in the DPRK, though presumably the ROK would
take the lead in rebuilding the Peninsula if it were the aggressor, and not too badly damaged bysubsequent hostilities (though that seems unlikely), reaching out to the international community
for help in doing so. Perhaps in either case, absent leadership from the United States, China
would play a key role to keep North Korean refugee flows into Northeast down, which could
presumably lead, if not accompanied by explicit agreements between the US/China/Russia, tofurther conflict due to having Chinese troops along the DMZ.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Uncertainties include whether Japan has, or could have within a very few years, the guided
missile technologies needed to carry out such attacks. The likely answer is yes, given Japan’s
advanced space program. How quickly the ROK could produce or acquire fissile material is also
a key question.
Policy lessons here include the lesson offered by several use cases, which is that it is likely to be
unwise to assume that the entire DPRK nuclear arsenal or most of its leadership can be destroyedby any kind of attack, short of actually killing the greater part of the DPRK population and thus
most of the military, and in the process making most of the northern part of the Peninsula (atleast) uninhabitable. It may also be unwise to underestimate the degree to which the DPRK
population is convinced by the domestic narrative about the outside world offered by DPRKReducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 185

leadership, and thus to overestimate the degree to which the DPRK population might accept
ROK (or, for that matter, Chinese or international) control over DPRK territory.

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Nuclear Weapons Use by Terrorists

Whether using nuclear weapons and/or weapons production technologies and nuclear materials
and/or nuclear weapons delivery systems obtained from the DPRK or from other sources, nuclear
weapons detonations by terrorist groups could happen in Northeast Asia or elsewhere, likely with
global consequences. (Note that the detonation of a nuclear weapon in the Middle East by aterrorist group is a triggering event for the “Response to DPRK Proliferation” first use by theUnited States, above.) Three discrete use cases started by first use of nuclear weapons by aterrorist organization are outlined below as “variants,” but these case hardly exhaust—andperhaps do not even scratch the surface of—options for such use cases.
In addition, it has been argued that the many types of possible terrorist attacks involving nuclear
weapons could be, particularly as time goes on, compounded and confounded by the use of
artificial intelligence and cyber-warfare technologies that have increasing capabilities to makethe causes and groups behind a given attack murky. Confusion of this type may cause nucleararmed states to erroneously identify the source of an attack, enhancing the possibility for
escalation.
Each of the variants, below, involving terrorist first nuclear use, being premeditated, is likely
closer to intentional than unintentional. The designation of the third variant is a little moredifficult, as a state’s weapon is being co-opted, and therefore the launch certainly qualifies asaccidental from the point of view of that state, if not from the point of view of the terrorist or
hacker.
Triggering Events and First Use
Variant 1: A terrorist organization causes a “9/11 type” event84 in Tokyo. This occurs when asmuggled-in rudimentary nuclear warhead (or maybe one stolen or sold from Russia or sold by
the DPRK) is detonated by either an Al Qaeda affiliate to punish Japan for its support of theUnited States, by a domestic terrorist group (perhaps a scion of Aum Shinrikyo),85 or by aterrorist group in Japan sponsored in part by another state, possibly the DPRK.86 A terrorist
attack on a nuclear reactor spent fuel pool in Japan is also possible, but wouldn’t seem to be as
much in keeping with the goals of a terrorist organization as an attack on a city.
Variant 2: A terrorist attack, again with a smuggled nuclear weapon, results in a NUDET in a
Chinese city, possibly Beijing. The attack is carried out by a domestic Chinese group possibly
claiming to represent Xinyang or Hong Kong, and with the stated aim of bringing international

84

That is, an event designed to cause many civilian casualties and thus to focus world attention and outrage, as in
the attack on the World Trade Center towers and other targets using civilian planes as weapons carried out on
September 11, 2001.
85
See, for example, Counter Extremism Project (undated, but apparently 2021), “Japan: Extremism and Terrorism,,
available as https://www.counterextremism.com/countries/japan
86
See, for example, Bruce Bechtol (2010), “North Korea and Support to Terrorism: An Evolving History,” Journal ofStrategic Security, Volume 3, Number 2: Summer 2010, available ashttps://www.jstor.org/stable/pdf/26463130.pdf

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87attention to the plight of the Uighurs. The source of the nuclear weapon could be a former Soviet
republic in Central Asia, a device purchased in the Middle East through intermediaries, possibly
even of DPRK origin, or even (though perhaps less likely) a weapon stolen or diverted from a
Chinese nuclear armory.
Variant 3: A cyberattack in which hackers working for a terrorist organization, or possibly justhackers, somehow gain internet access to a nuclear weapon, are able to ready a nuclear-tipped
missile for launch and are ultimately able to actually launch it. The missile belongs to one of theUnited States, China, or Russia, although it may (or may not) be more reasonable to assume thatthe missile is Chinese or Russian rather than American, as most of the US missiles in the region
are likely to be on ships and submarines.87 If the hackers are also terrorists, they may attempt to
aim the missile at a target offering maximum potential for damage, such as dense populations inSeoul or Tokyo (labeled “Use by Terrorists V3-1” in Figure 3), or may aim at a major US base in
the region (Okinawa or one of the bases in the ROK—“Use by Terrorists V3-2” in Figure 3). If
the missiles co-opted are Chinese or Russian ICBMs, they could possibly be targeted at theUnited States. If the hackers are just hackers, they may not actually try to target the missile, andjust accept its default targeting, which would probably, for US or Russian missiles, mean an open
ocean target (a change made after the end of the Cold War—“Use by Terrorists V3-3” in Figure3), but it is apparently not clear whether Chinese nuclear missiles likewise have default openocean targets.88
How the Conflict Evolves
Variant 1: Although the terrorist group claims responsibility for the attack on Japan, evidence
gathered at the scene of the attack, follow-up forensic work, and/or criminal investigations leadJapanese authorities to assume or perhaps provide proof of DPRK involvement as a proliferator
and ask the United States to respond, thereby invoking the “nuclear umbrella” as in the “Promise
is a Promise” cases above.
Variant 2: Several options exist for evolution of this variant. If convinced (or if it is convenient
to assume) that Uighurs are involved, China might adopt a “scorched-earth” response on its own
territory, with or without nuclear weapons (if the latter, maybe calling it a “failed nuclear test”?)
after giving Han Chinese residents of Xinyang time to evacuate, that might bring the UnitedStates and the broader “West” into the conflict. The question is whether it is plausible, given
Chinese security and what is probably the limited means of Muslim terrorists in China, whether
they could mount such an attack. Possibly not.
Alternatively, China might assume the United States was behind the attack, or supported it, if
relations between the United States and China were sufficiently eroded by then. China might87

It is assumed that DPRK missiles cannot be “hacked” because there is no international internet access to militarycommand and control in the DPRK and/or systems for launching nuclear-tipped missiles—if any, nuclear missiles,
in fact, are kept fully assembled—are likely to be more manual than in other nations.
88
Sico van der Meer (2018), “Reducing nuclear weapons risks: A menu of 11 policy options” Clingendael/
Netherlands Institute of International Relations, Policy Brief dated June 2018, available ashttps://www.clingendael.org/sites/default/files/2018-06/PB_Reducing_nuclear_weapons_risks.pdf

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decide to counterattack with nuclear weapons on for example, a US aircraft carrier group, which
would probably precipitate a conventional and nuclear war at sea between the two navies. It isalso possible that the attack could be ascribed to Taiwan or to protestors in Hong Kong, again
with United States involvement. In the former case, which might induce China to use nuclear
weapons in the waters off of Taiwan (but not on Taiwan itself, wishing, at a minimum, not to
contaminate the real estate and infrastructure there) as a prelude to an invasion of Taiwan withconventional weapons. In the latter case, it would probably mean a military lockdown on HongKong. Either case would see millions of refugees, if they could get out of China and a likely
confrontation between China and the United States that could go nuclear as a result ofbrinksmanship by one side or the other. If China finds evidence of DPRK involvement inproviding the weapon, it might choose not to attack the DPRK, not wishing to provoke a flow of
refugees into its Northeastern provinces, but would likely close the border, and cut off energy
supplies and other aid and trade to express its displeasure.
Variant 3: A wide range of case evolution pathways are possible here. After launch of the
hijacked missile, several case variants are possible. When the missile launch is detected,
adversaries (assumedly the US) could assume that the launch was on purpose and launch a
retaliatory strike while attempting to engage ABM batteries to shoot the missile down (which
would likely fail, per the analysis provided in the paper provided for this Project by David
Wright, particularly if the target was relatively close to the point of launch). This would be
followed by retaliatory strikes from the nation whose missile was hacked.
Alternatively, the hacked nation could quickly realize what has happened and contact theadversary nation to provide a warning and explain, which may or may not be in time if themissile is traveling within the region. Or, depending on the type of missile hijacked, the hacked
nation could regain control of the missile and blow it up in flight, perhaps causing some damageon the ground, but avoiding a nuclear detonation—though it seems that this option does not exist,
at least, for nuclear ballistic missiles.89
Use Case Consequences
Variant 1: A terrorist attack on Japan or the ROK with a nuclear device, unless traced to the
DPRK or blamed on another state, could be expected to be followed with renewed attention on
nonproliferation and antiterrorist initiatives, which might ultimately result in a more secureworld, albeit one with more surveillance and fewer freedoms. If traced to/blamed on the DPRK
or another state, nuclear punishment of the DPRK or other state is possible, likely leading toextended exchanges for as long as both combatants have serviceable weapons. Redoubled
pressure on the DPRK (or other state) to yield to international demands and begin to negotiate on
nuclear safeguards and disarmament is another possible outcome.
Variant 2: As noted below and above, key uncertainties exist as to how this use case might playout. It is possible that, if China treats it as a purely domestic matter, it will gain some sympathy
from the international community for being targeted, as the United States did after the 9/11
89

Union of Concerned Scientists (2015), “Frequently Asked Questions about Taking Nuclear Weapons Off
Hair-Trigger Alert,” Fact Sheet, dated January 2015, and available ashttps://www.ucsusa.org/sites/default/files/attach/2015/01/Hair-Trigger%20FAQ.pdf

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89attacks, and receive help in rebuilding from abroad. If China opts for harsh collective punishmentof the Uighurs or other minorities, this goodwill could rapidly evaporate.
Variant 3: In instances where the targeted nation assumes intent to fire the weapon on the part of
the hacked nation, this Variant probably results in escalating exchanges of warheads between atleast the two nations involved, and possibly, depending on alliances and other factors, nuclear
weapons use on targets elsewhere in the world as well. In cases where the hacked nation warns
the targeted nation, or the missile is somehow aborted before it reaches its target, a period or
frantic diplomacy would ensue, with some in the targeted nation believing that the strike wasintentional and calling for retaliation, and others trying to get the parties to stand down. It is not
yet clear to us how this case would fully play out. If the “stand down” contingent prevails, but
the incident captures public attention, much more attention to nuclear safeguards anddisarmament could ensue, with the possibility for significant progress in nuclear threat reduction
as a result. That outcome is hardly a given, however.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
For Variant 1, a key uncertainty is whether the terrorist group would be interdicted before it isable to detonate a nuclear device. If it is, in addition to incandescent attention being focusedworldwide on the terrorist group itself, enhanced global efforts to prevent proliferation might
result, with proliferating operatives (including state and non-state actors) more likely to be seized
and punished. For some attacks (particularly if carried out in Japan or the ROK, but also in the
United States), it is possible that blame could fall on the DPRK, changing the dynamic for any
ongoing negotiations or conflicts.
For Variant 2, in addition to whether domestic terrorists within China would have thewherewithal to carry out such an attack, it is uncertain whether any collective punishment China
would carry out on implicated ethnic groups would rise to a level that some international force,probably led by the United States and Europe, would feel obliged to invade Chinese territory. It
seems more likely that economic and political sanctions—ratcheting up pressure that has beenbuilding for a number of years and is, as of this writing (January 2022), manifesting in a politicalboycott of the Beijing Winter Olympics by the United States and a number of other nations—would be applied.
For Variant 3, key uncertainties lie in the attribution of blame for the attack. If it is recognizedthat it was a non-state group that caused the missile to be launched, and that group is swiftly
brought to justice, it is possible that a post-9/11-like period of focus on preventing such attacks,
and on controlling nuclear weapons, could ensue.
Key initial policy lessons from these three cases could include:•

Intensify work internationally to identify and foil nuclear proliferation networks.

•

Work internationally to improve control of all nuclear devices and fissile material,
possibly including the creation of international oversight authorities to enhance protectionof nuclear material, although it may well be difficult to get any nuclear weapons states to

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 190agree to inspections, let alone states like the DPRK (or Israel, for example).90
International cooperation to reduce stocks of fissile materials should be encouraged.
•

Establish or enhance communications facilities between nuclear states, possibly even
including the DPRK, such that if a nuclear launch from a nuclear weapons state occurs
through the actions of a terrorist or hacker, other states can know about the launch
immediately, take any applicable defensive measures, and refrain from retaliation against
the state where the weapon is launched.

90

Although it would in theory be possible for the nations of Northeast Asia to agree upon and implement a
regional nuclear inspection authority, perhaps modeled on Euratom, China so far has refused to agree to thedevelopment of such an international authority in Asia. Euratom, the European Atomic Energy Community, wasestablished in 1957 to govern markets and movement of nuclear goods and expertise in Europe. See, for example,
Institute for Government (2020), “Euratom,” dated February 24, 2020, and available ashttps://www.instituteforgovernment.org.uk/explainers/euratom

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913.6 Other Potential Use Cases and “Wild Cards”
As indicated above, we certainly do not mean to suggest that the use cases above even begin toexhaust the reservoir of nuclear weapons use cases that could affect the Northeast Asia region. A
small sampling of other cases that might be considered might include:•

Taiwan, faced with an impending military threat from China, and unsure of support froma distracted United States, attempts to bring Russia and its nuclear weapons into theconflict.

•

A shooting war that erupts between China and India in their contested border region
heats up to the point of nuclear weapons use, and regional powers are soon embroiled in
the conflict.91•

A nuclear conflict between India and Pakistan spills across other borders, with effects on
Northeast Asia’s environment, security situation, and policy choices.

•

The potential of a “rogue general” in one of the nuclear weapons states deciding tolaunch nuclear weapons (and the degree to which doing so might or might not betechnically impossible in each of the states holding nuclear weapons.

Although we have not (and do not plan to) elaborate these cases in our work, consideration ofthese “wild card” eventualities should be part of the calculus when working to establish policies
to reduce the threat of nuclear use in Northeast Asia.

91

The longstanding, but mostly non-violent, border dispute between China and India has taken a turn toward
military conflict and been in the news of late. See, for example, Saheli Roy Choudhury (2021), “India and China’s
border dispute will not end anytime soon, former ambassador says,” CNBC, dated, November 2, 2021, andavailable as https://www.cnbc.com/2021/11/03/india-china-border-dispute-unlikely-to-end-anytime-soonnirupama-rao.html

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4

Summary of Use Case Development and Initial/Provisional Policy Lessons

Just over 76 years ago, as of this writing, the United States, in what was described at the time as
an attempt to bring the Second World War to an abrupt end, dropped nuclear bombs, within aninterval of three days, on the Japanese cities of Hiroshima and Nagasaki. The bombings reduced
massive parts of the cities to rubble and caused horrific suffering and loss of human life.92 Since
those terrible August days in 1945, eight more nations have joined the United States in the“nuclear weapons club,”93 with several nations either having had nuclear weapons and given
them up, having tried to acquire nuclear weapons, or appear, in the case of Iran, to be headingalong the path toward the acquisition of nuclear weapons.
The bombings of Hiroshima and Nagasaki (a memorial to “ground zero” in Nagasaki is shown inError! Reference source not found.) remain the only instances in history of nuclear weapons detonation in a conflict. In the three-quarters-of-a-century since, nuclear weapons have been“used” primarily as tools of deterrence—deterring conventional and nuclear attacks on thenations that possess them and on the allies of those nations. That said, there have been, duringthat interval, many documented instances, and probably many that remain state secrets, when
nuclear weapons use was narrowly averted, sometimes by the bravery of someone in the nuclear
chain of command, and sometimes, just by luck.94
Any detonation of nuclear weapons in a conflict today (or in the years to come) risks absolutely
unacceptable consequences, no matter how “limited” the nuclear exchange is or will be.95 Thatsaid, the premise of this report is that it is crucial to understand a range of possible nuclear
weapons “use cases”—the detonation of nuclear weapons at or near the earth’s surface in a
conflict situation—to demonstrate the impacts of such use, and to spur the development of policy
options that can be deployed to reduce, minimize, and ultimately eliminate the risks of nuclear
war occurring in the future. We must stress that the mere fact that these cases are posited here
does not mean that they are likely; just that they are plausible. And although some of the use
cases do include only limited use, and in one case, failed use, of nuclear weapons, and lead,

92

See, for example, Masao Tomonaga (2019) “The Atomic Bombings of Hiroshima and Nagasaki: A Summary of the
Human Consequences, 1945-2018, and Lessons for Homo sapiens to End the Nuclear Weapon Age,” Journal for
Peace and Nuclear Disarmament, 2:2, 491-517, available ashttps://www.tandfonline.com/doi/full/10.1080/25751654.2019.1681226
93This count includes Israel, which is widely believed to possess nuclear weapons but has a policy of “deliberate
ambiguity” regarding its nuclear weapons status.
94
See, for example, Union of Concerned Scientists (UCS, 2015), Close Calls with Nuclear Weapons, Fact Sheet,
dated April 2015, and available ashttps://www.ucsusa.org/sites/default/files/attach/2015/04/Close%2520Calls%2520with%2520Nuclear%2520Wea
pons.pdf
95
Even in the event that a nuclear detonation was successfully configured to avoid causing casualties or significant
destruction, such use would be a breaking of the international taboo against the use of nuclear weapons in a
conflict, and would risk escalation of the conflict to additional use of nuclear weapons.

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ultimately, to a meeting of the minds between nuclear-armed opponents and the eventual
reduction of the risk of nuclear war, none of these use cases are in any way desirable in and ofthemselves, and all possible efforts should be made to avoid any nuclear weapons use.

Figure 5. Memorial to “Ground Zero” in Nagasaki.96
4.1 Summary of Use Cases
The nuclear use cases posited above span the range of cases where a nuclear detonation is
attempted but is not successful, and the adversary that is the recipient of the attack exercises
sufficient restraint that no counterattack with nuclear weapons occurs, through a variety of cases
where conflict involves a nuclear weapons detonation, in most cases followed by a nuclear
counter-attack, but in which diplomacy results in the exchange being “limited” to a few targets,to cases where it is hard to see how a conflict would result in anything short of global (or nearglobal) nuclear war. The reader should not, however, take our definition of a range of cases as
96

Image obtained as free download from the website of Nagasaki Prefecture Convention and Tourism Association,
Nagasaki Prefecture. https://www.discover-nagasaki.com/en. Downloaded on January 14, 2022.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 194meaning that nuclear war of any kind is acceptable or preferred in any sense. Nuclear war of any
kind is a human and ecological (and economic) tragedy, no matter what, and virtually any use of
nuclear weapons risks reactions by other states that could plunge the world into a global nuclear
conflict. This tragedy occurs whether nuclear use is intended or unintended, including the use of
nuclear weapons for so-called "escalation control."97 It is therefore not particularly importantwhether one case has lesser or greater consequences compared to another, as any case could,
given possible changes in events or leadership decisions, end up as a “worst case” global
conflagration with a likelihood that is essentially unknowable, and thus sets a floor on the typesof policies that must be implemented to reduce the risk that nuclear war will happen.
In the examples above, we have broken the elements of use cases into “Triggering Events andFirst Use,” “How the Conflict Evolves,” Use Case Consequences,” and “Use Case Uncertainties,
Ultimate Outcome, and Policy Lessons.” This breakdown is to some extent artificial as some of
the categories overlap. Moreover, any use case could go in a different direction at multiple points
and result in different outcomes. The use cases above posit more numerous first use options forthe DPRK and the United States, as these are the principal antagonists on the Korean Peninsula,which has been for many years a primary, but hardly the only, locus of conflict in Northeast
Asia. There are, however, certainly additional first use cases that could be devised for China, andto an arguably lesser extent, Russia and other actors. Below we list some of the key similarities,
as well as differences, between the use cases considered above.
The similarities between use cases include:•

Many of the use cases involve first use in which one adversary misinterprets the actionsof another. These misinterpretations include underestimating an opponent’s capabilities,
resolve, or reaction to a provocation.

•

Many of the use cases turn on the personality of a leader, and how he or she responds toa crisis involving nuclear weapons.

•

Many of the use cases occur when one or more of the adversaries, or at least theleadership of same, are distracted by other issues, including domestic issues and issues
abroad.

•Many of the use cases involve lack of communications, or lack of timely or clear
communication, between rivals and, in many cases, between allies, or even between those97

The use of nuclear weapons for escalation control implies their use in such a way as to force an adversary to thenegotiating table, and thus to end (or at least limit) escalation. The argument here, however, is that an applicationof nuclear weapons for escalation control remains so uncertain in terms of its outcome as to be as unacceptably
risky as other uses of nuclear weapons. See, for example, Mark B. Schneider (2017), “Escalate to De-escalate,” U.S.
Naval Institute Proceedings, dated February 2017, and available ashttps://www.usni.org/magazines/proceedings/2017/february/escalate-de-escalate; and Kevin Ryan (2020), “Is'Escalate to Deescalate' Part of Russia’s Nuclear Toolbox?” Russia Matters, Harvard Kennedy School Belfer Center
for Science and International Affairs, dated January 8, 2020, and available ashttps://www.russiamatters.org/analysis/escalate-deescalate-part-russias-nuclear-toolbox

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responsible for operating the assets of a single military. The latter includes establishmentof clear expectations as to the operation and limits of the US nuclear umbrella over its
allies in the region.
•

Many of the cases include key decision points where either escalation or de-escalation ofa nuclear conflict is possible, based on the choices (or failures to choose) of military andcivilian leaders at those moments.

•

Many of the cases may involve large uncertainties with regard to the outcome of thenuclear conflicts. It is difficult to foresee what would happen once a nuclear weapon isused, and any nuclear weapons use could escalate to an uncontrollable nuclear conflictregardless of what of decision makers want or intend.

Key differences between use cases include:•

Although many use cases use similar delivery systems—dictated in part by the distance
between adversaries as well as their arsenals—some use very different means ofmoving nuclear weapons to targets, and thus require different sorts of policy
approaches to reduce the threat of nuclear use.

•

The nuclear arsenals that potential adversaries have, at this point, differ substantially inboth quantity and quality, which colors the decisions to use or not use nuclear weapons.

•

The nuclear weapons arsenals of the potential adversaries, and the technologies that canbe used to deliver them, are not static. Security challenges a few years from now may be
addressed by very different weapons than are currently used.

•

The adoption, or rejection, of opportunities for stopping conflict through negotiation.
Different approaches to negotiation may produce significantly different outcomes tonuclear conflicts, although the effectiveness of negotiation can also vary widely.

4.2 Initial Policy Lessons
As noted earlier in this report, the development of use cases in this year of the Reducing the Risk
of Nuclear Weapons Use in Northeast Asia Project is to be followed by the evaluation of use
cases next year, and the development of policy options (and communications to policymakers) inproject year 3. That said—and being exquisitely conscious of the existential risk that nuclear
weapons pose and the need for the international community to move swiftly on devising andimplementing policies to reduce those risks—we offer the following initial thoughts about theramifications of the use cases above for policies that may serve to reduce the risk of theoccurrence of nuclear weapons use. Some of the policy lessons below are derived from particularuse cases—see notations in Table 2—and some are the result of the consideration of multiple use
cases.

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96•Open trusted and reliable lines of communications between adversaries at multiple levels
and keep them open. This would include communications between national leaders,military leaders, and working-level military commanders.98•

Specifically, with respect to reducing the potential for military exercises on either side of
the DMZ (or, by extension, in the waters around Taiwan or elsewhere) to inadvertently
convince an adversary that an attack was imminent (a potential triggering event forseveral use cases above), specific polices encouraging observers from the adversary side
to be involved in all exercises should be encouraged. Exercises close to the territorialboundaries of potential adversaries should be avoided. These types of policy measures
could help to counteract the expanding role of “stealth” submarines and aircraft, which
are less visible to adversaries and thus more of concern.

•

To improve mutual trust, for both allies and adversaries, encourage transparency andconsistency in describing the extent and operation of military alliances.

•

Further identify reasons and modes for accidental or unintended use of nuclear weaponsand make changes to command-and-control procedures to minimize those uses.

•

Seek to separate as much as possible the operation of international relations fromdomestic political concerns, particularly (but hardly exclusively) in nations whereleadership changes are frequent.

•

Relatedly, seek to insulate the operations of nuclear weapons from the personal orpolitical vagaries of national leaders, possibly by strengthening oversight on the use of
nuclear weapons by other government leaders, as well as the military.

•

Seek to fully brief leaders, military and otherwise, regarding the possible goals, concerns,
and emphases of adversaries, to allow leaders to better understand and, to the extent
possible, predict or offer options as to how opposing leaders might react in situations ofstress. This will also involve obtaining a full (or as full as an outsider can achieve)
understanding of the history of an adversary’s military position and role of nuclear
weapons within it.

•

Impress upon policymakers that, particularly in an arena like Northeast Asia where manypotential adversaries are nuclear armed, maximum restraint should be exerted to avoid
even a conventional war or “limited” nuclear war. Given existing tensions anddifferences between the states of the region, relatively small and often unforeseen events,
miscalculations, or misunderstandings can result in the rapid escalation of conventional
conflicts into extensive nuclear conflicts, and what may have been intended to be limited,
specific-purpose use of nuclear weapons can also rapidly escalate.

•

For each state, institute policies to brief the political and military leadership of potential
adversaries with regard to the state’s goals and intentions, and encourage other states,

98

See, for example, BBC News (2021), “North and South Korea restore hotline after a year,” dated July 27, 2021,
and available as https://www.bbc.com/news/world-57979937

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including adversaries, to do the same. Signals of goals and intentions can take form ofboth public declarations and private bilateral strategic dialogue.
•

Exercise patience, and adjust expectations for results, in international negotiations,particularly those involving the DPRK. Specifically, although this will be difficult for
many leaders to hear, do not expect, even if negotiations with the DPRK seem to be
progressing very positively, that the DPRK will give up its nuclear weapons within a few
years. A decade is more likely, and even then, stringent international oversight of afrozen DPRK nuclear weapons program is a more achievable goal.

•

Equip nuclear weapons systems with redundant command and control mechanisms that
help to assure that nuclear weapons can never be launched without adequate authority
and oversight.

•

Work toward insulating key systems (electric power and communications among them)from HEMP bursts, and/or develop robust back-up arrangements designed to keep thosesystems running.

•

Anticipate that potential breakdowns in communication in the nuclear command andcontrol will occur, whether because of, for example, a HEMP detonation or cyberattack,or because of natural disasters such as earthquakes or severe “solar storms,”99 and assurethat commanders in possession/control of nuclear weapons have clear orders as to what to
do in those instances.

•

Build awareness of the various and serious threats posed by the current nuclear weapons
situation in the region, of the arguably eroding security situation, and thus, of the urgent
need to address these threats. A metaphor for the nuclear (and, for that matter,
conventional) weapons security situation in the region might be that the people of theregion are collectively standing on the very edge of a sandstone cliff, battered by theforces of wind, rain, and waves, looking down at a growing pile of rubble at its base, andunsure where and when further erosion will take place. That is, the nuclear precipicemight give way in any number of ways that we can’t anticipate, but with consequences
starting with devastation and ratcheting up from there. In addition to those failure modes
that we can guess at (including those above), it is thus crucial to develop policies that halt
erosion and enable a safe retreat from the cliff’s edge for all parties—that is, devise ways
forward to reduce the nuclear threat—before irreparable harm is done.

•

Engage civil society to help to both devise policies to reduce nuclear threats and topressure governments to implement threat-reduction policies. This might include seeking
to amplify the voices of both non-governmental groups and of governments at the sub-99

“Solar storms” is a general term for events such as solar flares, ejections of solar energetic particles (protons),
coronal mass ejections, and other solar phenomena that can cause geomagnetic storms on earth. These events can
include emissions of X-rays, radio waves, and particles that can disrupt and/or damage space-based (such as global
positioning systems) and other electronics and communications systems, and geomagnetic storms can induce“extra currents in the ground that can degrade power grid operations.” See, for example, Space Weather
Prediction Center, National Oceanic and Atmospheric Administration (United States, 2022), “Space Weather
Impacts”, available as https://www.swpc.noaa.gov/impacts

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national level, such as stakeholders in the major cities that might become targets fornuclear use in some of the use cases explored above.
•

Bring parties in the region to the table to discuss the acceptable outlines of nuclear
weapons free zones (NWFZ), including, for example, one on the Korean Peninsula.

•

Encourage all nuclear weapon states to adopt a “No-First-Use” declaration policy as astep toward substantially reducing the risk of nuclear war. The declared nuclear weapons
states (NWS) in the region should endorse such policies. A recent statement by theleaders of the NWS affirms that a “nuclear war cannot be won and can never be fought,”
and that “nuclear weapons…should serve defensive purposes, deter aggression, andprevent war”, but does not go so far as to endorse No-First-Use policies.100 Declaration
and adoption of No-First-use policies, if undertaken by all parties holding nuclear
weapons, would help to reduce the risk of nuclear war in Northeast Asia, and would
likely also open the door to further discussions on threat reduction and disarmament.

•

Implement stronger international efforts to secure and possibly reduce stocks of fissile
materials and/or to discourage further production of fissile materials.

4.3 Outstanding and Unresolved Questions
Our findings above, including the initial policy lessons offered, are of necessity limited by our
research and input from commissioned authors and others in the first year of the NU-NEA
project. Work to date has identified areas in which additional project team and commissioned
research will be needed in the second and third years of the project.
An initial list of key remaining and/or unresolved questions that need to be addressed as use
cases are developed and evaluated include:•

Additional research by the project team, likely augmented by commissioned papers, will
be needed to determine how standing rules of engagement will likely be interpreted under
different use cases by different militaries, that is, which weapons would likely be used,
and under what circumstances.

•

Relatedly, additional research will be needed as to the scope for and entry points forpolicies that might make such standing orders to the hands that control nuclear weapons
more flexible, such that opportunities for diplomacy can be offered and accepted before
weapons are fired.

•

Additional research may be needed to better understand the current and evolving military
doctrines, including under new administrations, in the United States, China, and Russia.

100

See, for example, The White House (United States, 2022), “Joint Statement of the Leaders of the Five NuclearWeapon States on Preventing Nuclear War and Avoiding Arms Races,” dated January 03, 2022, and available ashttps://www.whitehouse.gov/briefing-room/statements-releases/2022/01/03/p5-statement-on-preventingnuclear-war-and-avoiding-arms-races/

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•Information needs to be compiled regarding the vulnerability of key infrastructure,including nuclear power plants and their ancillary facilities, to HEMP bursts, and as towhether those vulnerabilities vary substantially by country.

Some of the types of Year 3 NU-NEA project research on the policy implications of the use
cases explored in this Report include (but are not limited to) the following. Note that the Projectis unlikely to be able to pursue all of these research options.
•

Policies that might address accidental and cyber-attack risks of nuclear weapons use.

•

Research into pre-emptive strike doctrines in use among the nuclear actors in Northeast
Asia and policies designed to address problems with existing pre-emptive strike
doctrines.

•

Research into technologies, plans, and policies for deployment of tactical nuclear
weapons in the region and on policies to address issues related to tactical nuclear
weapons deployment.

•

Research into nuclear weapons confidence-building measures to reduce nuclear weaponsrisks that are in use globally and on the possible deployment of such measures inNortheast Asia.

•

Research into and development of the diplomatic and negotiation steps that would be
associated with reducing and ultimately eliminating the role of nuclear weapons inmaintaining the security of Northeast Asia.

•

Research into international legal opinions on the lawfulness of nuclear weapons use,
including whether legal work on the topic has reflected the environmental/climate
consequences of nuclear use, and if not, how that consideration might (or might not)change legal perspectives.

•

Research to characterize the nuclear weapons debates in each of the states of the region,
including those what do not yet have them (especially the ROK and Japan, but possibly
Taiwan and other nations as well), and to evaluate how those debates might affect theprospects for addressing nuclear security issues in the region.

•

Consider the different impact of nuclear weapons “reduction and removal” versus“reduction and elimination” strategies, as these strategies may have different impacts on
security and deterrence. Reduction and removal could include removing weapons, either
fully intact or with their fissile material intact, from a state or a region, and either placing
them in storage elsewhere under the authority of the country that owns the weapons or
placing them in storage under some sort of international authority. Reduction andelimination denotes dismantling the weapons and diluting (or using in civilian reactors)
the fissile material so that it cannot be directly used in a weapon.

•

Explore how and why the growing US/China “cold war” might affect nuclear weapons
deployment, nuclear weapons use prospects, and regional governance needs,
opportunities, and challenges in Northeast Asia.

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•

Explore and evaluate how perceptions of US behavior (and changes in same) in theinternational arena in recent years has affected NEA perceptions of the United Statesfrom the point of view of international security in general, and nuclear security inparticular, and how those changing perceptions may change the prospects for addressing
nuclear weapons issues in the region. (Similar research could be undertaken focusing on
China and Russia as well.)•Consider how the current asymmetries of armaments—including nuclear weapons,delivery systems, and missile defense systems—between the powers in Northeast Asia
affect both the prospects for nuclear weapons use and the opportunities, approaches, andchallenges that might be used in the region to enhance nuclear security.

•

Research into how developing military hardware and software technologies (the latterincluding applications of artificial intelligence) might shift considerations for how anuclear conflict might come about and what policies might be developed andimplemented to address nuclear security.

•

Study security arrangements in other regions, such as the Association of Southeast Asian
Nations (ASEAN) and Europe, for applicability (and non-applicability) to the reductionof nuclear weapons threats in Northeast Asia.

•

Explore futures for the region (and the broader international community) that do not
involve nuclear conflict, identify how those futures might come about, and evaluate these
non-use cases to derive additional policy lessons for avoiding nuclear weapons use.

•

Explore the roles that other regions—particularly Europe—might play in helping to
reduce nuclear threats in Northeast Asia—including evaluating how policymakers andother stakeholders in other regions view conflicts in Northeast Asia and what changes
might help them to play a useful role in improving the nuclear (and general) security
environment in the region.

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Glossary
ABM

Anti-ballistic missiles are systems used to attempt to intercept incoming
missiles, either while those missiles are rising (boost phase interceptors) inspace or falling and nearing their target.

AI

Artificial intelligence (applied to automate of nuclear weapons launchsystems).

ASEAN

Association of Southeast Asian Nations.

Cold WarThe Cold War was a conflict in the aftermath of World War II through 1989
between competing blocs led by, respectively, the United States and USSR, inwhich there were few active military engagements but significant build-up ofarmaments and global tension regarding potential nuclear conflicts.

CTBT

Comprehensive Nuclear Test Ban Treaty.

Deterrence“Deterrence [is a], military strategy under which one power uses the threat ofreprisal effectively to preclude an attack from an adversary power,”101 such as
using the threat of use of nuclear weapons to deter an attack by another withconventional or nuclear weapons.

Dirty Bomb“A ‘dirty bomb’ is one type of a radiological dispersal device…that combines
conventional explosives, such as dynamite, with radioactive material. The
terms dirty bomb and RDD are often used interchangeably. Most RDDs would
not release enough radiation to kill people or cause severe illness….However,depending on the situation, an RDD explosion could create fear and panic,
contaminate property, and require potentially costly cleanup.”102

DPRK

Democratic People’s Republic of Korea.

EMP

Electromagnetic pulse. See also HEMP.

Enrichment

The process of raising the proportion of the uranium-235 isotope in natural (oralready enriched) uranium by separating U-235 from U-238, typically by aprocess of centrifugation of uranium hexafluoride (UF6) gas.

EU

European Union.

101

Brittanica.com (probably 2017), “Deterrence, political and military strategy,” available ashttps://www.britannica.com/topic/deterrence-political-and-military-strategy
102
US Nuclear Regulatory Commission (2020), “Backgrounder on Dirty Bombs,” last updated August 29, 2020, andavailable as https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/fs-dirty-bombs.html

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Fallout“Fallout is the radioactive particles that fall to earth as a result of a nuclear
explosion. It consists of weapon debris, fission products, and, in the case of aground burst, radiated soil.”103

HEMPHigh Altitude Electromagnetic Pulse. A 2008 Report by the United States
Congressional Research Service (2008), for example,104 defines HEMP as“Electromagnetic Pulse (EMP) an instantaneous, intense energy field that canoverload or disrupt at a distance numerous electrical systems and hightechnology microcircuits, which are especially sensitive to power surges.”

IAEA

International Atomic Energy Agency.

ICBM

Intercontinental ballistic missile.

INF

Intermediate-Range Nuclear Forces Treaty. “The 1987 Intermediate-Range
Nuclear Forces (INF) Treaty required the United States and the Soviet Union
to eliminate and permanently forswear all of their nuclear and conventional
ground-launched ballistic and cruise missiles with ranges of 500 to 5,500
kilometers.”105 The United States withdrew from the INF treaty in 2019.

Isotopes

Species of an element with different numbers of neutrons in their nuclei andtherefore different atomic weights, such as U-235 and U-238.

KilotonA measure of the explosive power of a nuclear detonation, and nominallydenoting the amount of explosive force achieved by detonating 1000 tons of
2,4,6-Trinitrotoluene, or TNT. Typically defined as one teracalorie (1012
calories, or 4.184 x 1012 Joules), but definitions do vary by country and evenby organization within each country—see attachment on this topic for moredetail.

Kim Jong Un

Chairman and hereditary Supreme Leader of the DPRK. His father, Kim JongIl, until his death in 2011, served as the DPRK leader following the 1994
death of his own father, Kim Il Sung, who founded the DPRK state in 1948.

KPNI

Korean Peninsula nuclear issue.

MegatonA measure of the explosive power of a nuclear detonation equal to 1000
kilotons.

103

Atomicarchive.com (2020), “Radioactive Fallout,” available ashttps://www.atomicarchive.com/science/effects/radioactive-fallout.html
104
Clay Wilson (2008), High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices:
Threat Assessments, US Congressional Research Service, updated March 26, 2008, and available ashttps://www.wired.com/images_blogs/dangerroom/files/Ebomb.pdf. A more recent publication by the US Air
Force Civil Engineer Center (AFCEC, 2020), “High Altitude Electromagnetic Pulse (HEMP) Effects and Protection,”
updated 08-07-2020, and available as https://www.wbdg.org/resources/high-altitude-emp-effects-protection,
provides a description of the effect and of ways to protect equipment from EMPs.
105
Arms Control Association (2019), ibid.

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NC3

Nuclear command, control, and communications.

NEA

Northeast Asia.

NORAD

North American Aerospace Defense Command.

NPT

Treaty on the Non-Proliferation of Nuclear Weapons.106“Nuclear Umbrella” Extension of nuclear deterrence by a nuclear weapons state that is in effectan implicit or explicit guarantee to defend a non-nuclear allied state.
NUDET

Detonation of a nuclear weapon or other nuclear explosive device that derives
its explosive power, at least mostly, from nuclear fission and/or fusion
reactions.

NWFZ

Nuclear Weapons-Free Zone.

NWS

Nuclear Weapons States (declared).107

PGM

Precision-guided munitions, or precision guided missiles, are guided munition(or missiles) intended to precisely hit a specific target. PGM are also
sometimes called smart weapons, smart munitions, or smart bombs.

Plutonium

Element (symbol, Pu) found very seldom in nature, but produced by nuclear
fission reactions when Uranium-238 reacts with a neutron to produce (mostly)
Pu-239, which can be used to produce nuclear explosives (and in nuclear
energy reactors).

PRC

People’s Republic of China (China).

Reprocessing

The processing of spent nuclear fuel to remove and separate out the plutonium(Pu-239) produced when neutrons from nuclear fission collide with uranium238. The resulting plutonium can be used in “mixed oxide” fuel for nuclear
energy reactors, but it can also be used to make nuclear weapons.

RF

Russian Federation (Russia).

106

See, for example, United Nations Office for Disarmament Affairs (undated, but between 2015 and 2020) “Treaty
on the Non-Proliferation of Nuclear Weapons (NPT),” available ashttps://www.un.org/disarmament/wmd/nuclear/npt/
107
Wikipedia (2022), “List of States with Nuclear Weapons,” last updated January 6, 202, and available ashttps://en.wikipedia.org/wiki/List_of_states_with_nuclear_weapons, includes the following: “Five [states thathave announced having nuclear weapons] are considered to be nuclear-weapon states (NWS) under the terms of
the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). In order of acquisition of nuclear weapons these
are the United States, the Soviet Union (now Russia), the United Kingdom, France, and China”.

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ROE

Rules of engagement: “military directives meant to describe the circumstances
under which ground, naval, and air forces will enter into and continue combat
with opposing forces.108

ROK

Republic of Korea.

SAR

Special Administrative Region (of China, such as Hong Kong and Macao).

THAAD

Terminal High Altitude Area Defense—a ground-based missile defense
system deployed by the United States in the ROK and elsewhere.

Thermonuclear

A device that derives explosive energy from nuclear fusion reactions,sometimes in combination with fission reactions.

TNT

2,4,6-Trinitrotoluene, a high-explosive chemical whose yield of energy when
detonated is the basis for the definition of a “kiloton” of nuclear explosive
yield.

UN Command

The United Nations Command (UNC or UN Command) is the multinational(conventional) military force that supported and supports the Republic ofKorea during and after the Korean War.109

UNSC

United Nations Security Council.

UraniumNatural element (U) found fairly widely in the earth’s crust. The isotopic
composition of natural uranium is about 0.7 percent uranium-235, which isradioactive, with almost all of the rest being U-238, which is stable.

US

United States of America.

USFK

United States Forces Korea—the name of the US military force stationed in
the ROK.

Use Case

For the purposes of this report, a description of a case of nuclear weapons use
starting with the detonation of one or more nuclear weapons in an attack or
counterattack against a military opponent.

Weapons-grade U Uranium-235 (typically) of a purity sufficient for use in a nuclear weapon,
typically 90 percent U-235 or greater.

108

Britannica, The Editors of Encyclopaedia (2016), "Rules of engagement." Encyclopedia Britannica, last edited
2016, available as https://www.britannica.com/topic/rules-of-engagement-military-directives
109
See, for example, UN Command (undated) “Under One Flag,” available as https://www.unc.mil/About/AboutUs/

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Yongbyon

Location of the DPRK’s main nuclear weapons complex, including (at least) a“5 MW” reactor for producing plutonium, facilities for separating plutonium
from spent fuel, a small research reactor, a uranium enrichment facility, and a
recently built, but apparently not-yet used, experimental light-water reactor(ELWR) with an estimated capacity of about 25-30 MW (electric).

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ATTACHMENTS
ATTACHMENT 1: TECHNICAL DEFINITION OF “A KILOTON” AS USED IN
IDENTIFYING THE EXPLOSIVE POWER OF A NUCLEAR DEVICE110
As a measure of the explosive power of a nuclear device, the term “kiloton” has a number ofdefinitions. In fact, nations possessing nuclear weapons are free to define this term in different
ways, and as a consequence, weapons described as having a 10 kilotons of yield in two different
nations may have significantly explosive power, and thus will have different impacts when
detonated. In the second year of the NU-NEA project, the project team will be exploring thepotential impacts of nuclear weapons use—in terms of explosive and radiological impacts, healthimpacts, and impacts in infrastructure, for example—in the contexts of the use cases described in
the preceding report. As such, it will be necessary to understand how the rated kilotons of theweapons produced by each nation translate into actual ability to do damage when the weapons
are used. The discussion that follows explores what is known about the definition of a kiloton indifferent places and contexts, and will be used to guide the project team’s interpretation ofkiloton ratings of weapons for the purposes of project modeling efforts in year 2.
Since the days of the Manhattan Project, when the use of US Customary Units was still common
in science and engineering in the United States, the definition of the nuclear “kiloton” hasremained slightly ambiguous. Here follows a summary of the various definitions used and somepotential consequences of this ambiguity.
The original authoritative source on nuclear weapons, The Effects of Nuclear Weapons byGlasstone and Dolan, published by the US Department of Defense and US Department of Energy
in 1977, defines “kiloton energy” as “1012 calories. This is approximately the amount of energythat would be released by the explosion of 1 kiloton (1,000 tons) of TNT.” Furthermore, “thebasis of the TNT equivalence is that the explosion of 1 ton of TNT is assumed to release 109
calories of energy.”111
Table 1.45 from that source (reproduced below) summarizes various equivalences to one kilotonof TNT. According to Glasstone and Dolan, “the calculations are based on an accepted, althoughsomewhat arbitrary, figure of 1012 calories as the energy released in the explosion of this amountof TNT.112

110

The definition of kiloton” presented here draws from Appendix A in the paper “Potential Use of Low-Yield
Nuclear Weapons in a Korean Context,” by Eva Lisowski, as prepared for the Reducing the Risk of Nuclear Weapons
Use in Northeast Asia project, September 2021.
111
Samuel Glasstone and Philip J. Dolan, The Effects of Nuclear Weapons, Third Edition, pdf, available ashttps://www.dtra.mil/Portals/61/Documents/NTPR/4-Rad_Exp_Rpts/36_The_Effects_of_Nuclear_Weapons.pdf,
pages 644, 649.
112
Glasstone and Dolan, ibid, p. 13.

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Table 1.45: Equivalents of 1 Kiloton of TNT
•
•
•
•
•
•
•

Complete fission of 0.057 kg (57 grams or 2 ounces) fissionable material
Fission of 1.45 x 1023 nuclei
1012 calories
2.6 x 1025 million electron volts (MeV)
4.18 x 1019 ergs (4.18 x 1012 joules)
1.16 x 106 kilowatt-hours
3.97 x 109 British thermal units

Glasstone and Dolan explain the origin of some ambiguity surrounding these definitions:
The majority of the experimental and theoretical values of the explosive energy released
by TNT range from 900 to 1,100 calories per gram. At one time, there was someuncertainty as to whether the term “kiloton” of TNT referred to a short kiloton (2 x 106
pounds), a metric kiloton (2.205 x 106 pounds), or a long kiloton (2.24 x 106 pounds). In
order to avoid ambiguity, it was agreed that the term “kiloton” would refer to the releaseof 1012 calories of explosive energy. This is equivalent to 1 short kiloton of TNT if theenergy release is 1,102 calories per gram or to 1 long kiloton if the energy is 984 calories
per gram of TNT.113
Despite the formal definition equating one kiloton to a tera-calorie, Lawrence Livermore and Los
Alamos National Laboratories in the United States, for example, despite being two of the major
laboratories undertaking research and development on matters nuclear in the United States, havedebated the kiloton definition114 based on the immediate versus delayed fission yield of nuclear
weapons. The total energy released is equivalent to about 240 MeV per fission. However, afraction of this fission energy is carried away in neutrinos and delayed radioactive decay(fallout). Therefore, some consider the true definition of a kiloton to be equivalent to theimmediate explosive yield of 180 MeV per fission.
In practice, there a number of ways in which a given nuclear weapons program might define“kiloton” for the purposes of determining the yield of the weapons it produces. Possibilities
include calculations of yield based on the Einstein equation of nuclear energy release, E = mc2,
where E is the energy released in Joules when fission (or fusion) occurs with loss of mass m (inkilograms), and c is the speed of light (3 x 108 meters/second), and the calculating the yield as its
equivalent in high explosives (HE). These two measures may be as much a factor of two
different (for example, 2 kilotons of yield measured based on nuclear energy release required to
produce the same explosive energy as 1 kiloton of high explosives).

113

Ibid.
Walter Pincus (1978), “2 Labs Battle To Be No. 1”, Washington Post, dated December 12, 1978, and available ashttps://www.washingtonpost.com/archive/politics/1978/12/12/2-labs-battle-to-be-no-1/20a1a894-4867-4f9d97d0-183c6c6d844e/
114

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Acknowledgments: The text above incorporates ideas and comments from Siegfried Hecker,
Joseph Martz, Tom Knuckle, and Bob Brownlee.

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ATTACHMENT 2: CONSIDERATIONS WITH RESPECT TO USE CASES—
COMMISSIONED PAPERS
The following presents titles, authors, and abstracts (or in some cases summary introductions) forthe papers commissioned for the NU-NEA project that have been commissioned and completed
in the first project year. These papers have served to inform the development and discussion of
the use cases presented above and have been or will shortly be published by the NU-NEA project
partners as Special Reports.

Nuclear-Use Cases for Contemplating Crisis and Conflict in East
Asia
Paul K. Davis, senior principal researcher, RAND (retired, adjunct), and professor, Pardee
RAND Graduate School.
Bruce Wm. Bennett, professor, Pardee RAND Graduate School, and international defense
researcher, RAND (retired, adjunct).
Abstract
This paper motivates and sketches a set of nuclear-use cases involving conflict on the Korean
peninsula. The cases reflect a wide range of ways that nuclear weapons might be brandished orused in a Korean crisis. We identify possible cases by using two different lenses: a "logical" ortaxonomic lens and a decisionmaking lens that asks how an actual national leader might decide
to use nuclear weapons first. We then select cases from the space of possibilities to reflect that
range usefully. The use cases consider mistakes, unintended escalation, coercive threats, limited
nuclear use to reinforce threats, defensive operations, and offensive operations. They also
consider the potential role of fear, desperation, responsibility, grandiosity, indomitability, andother human emotions. Some use cases are far more plausible than others at present, butestimating likelihoods is a dubious activity. The real challenge is to avoid circumstances where
the use cases would become more likely.

Korean Peninsula Nuclear Issue: Challenges and Prospects
Anastasia Barannikova, research fellow, ADM Nevelskoy Maritime State University.
Abstract
For the last three decades the Korean Peninsula nuclear issue (KPNI) has been considered as oneof the most serious threats to security and stability in NEA (Northeast Asia). To date, none of theefforts by the international community – including Six-party talks, pressure and diplomaticefforts, and more recently, activity started by the Democratic People’s Republic of Korea
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(DPRK) in 2018-2019, have yielded tangible results in addressing the issue. This puts into
question the viability of the existing approaches to the DPRK and the feasibility of achieving a
KPNI solution.

Counterforce Dilemmas and the Risk of Nuclear War in East Asia
Ian Bowers associate professor at the Centre for Joint Operations, Royal Danish DefenceCollege.
Abstract
The discovery of new Chinese nuclear missile silos, a seemingly escalating nuclear-conventionalarms competition between the Democratic People’s Republic of Korea (DPRK) and the Republicof Korea (ROK), and the announcement that Australia, in concert with the United States andUnited Kingdom, is pursuing nuclear-powered attack submarines are events that collectively
indicate a worsening security environment in East Asia. Using geostrategic, operational, andtechnological factors as the basis for analysis, this paper contextualizes these and otherdevelopments and assesses the potential for nuclear war in East Asia in general and on the
Korean Peninsula in particular.
The most dangerous threat to strategic stability is a counterforce dilemma where theconventional weapons of the United States, China, and regional East Asian actors may create
strategic instability by their intentional or inadvertent entanglement or use to target the nuclear
forces of another state, resulting in pursuit of more secure second-strike capability by thecountries of the region, and forming the heart of conventional warfighting and deterrence
strategies. The many different conflictual or competitive relationships across the region makearms control initiatives unlikely to succeed, but the maritime nature of the geostrategic
environment and the lack of existential threat that the United States and China pose to each othermake offer fewer natural pathways to the use of nuclear weapons for either China or the UnitedStates than there were for the adversaries in the Cold War.

Nuclear Weapons and Delivery Systems that Might be Implicated in
Nuclear Use Involving the Korean Peninsula
Matt Korda. senior research associate and project manager, Nuclear Information Project
Federation of American Scientists.
Abstract
It is highly unlikely that the Democratic People’s Republic of Korea (DPRK) would intentionallylaunch nuclear weapons in the absence of an existential threat to the continued survival of thestate and its political leadership. However, in the event of such a scenario—for example, theprospect of an imminent US invasion or regime change operation—it is possible that the DPRKReducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 1

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would use some of its estimated forty to fifty nuclear weapons in an attempt to forestall US
action. In that case, the DPRK could use its short- and medium-range ballistic missiles early in a
conflict to strike political and military targets in the Republic of Korea (ROK) and Japan, and it
could potentially use its intermediate-range and intercontinental ballistic missiles to strike US
military targets on Guam and Hawaii. The DPRK could also hold some nuclear weapons inreserve to strike the continental United States with intercontinental ballistic missiles, in the eventthat its initial nuclear strikes did not prevent an existentially-threatening conventional invasion of
the DPRK. First nuclear strikes by the United States (and its allies), or by China or Russia, arealso highly unlikely in the absence of an overwhelming provocation, but the nuclear weaponsand launch systems available to these states are also considered.

Reducing or Exploiting Risk? Varieties of US Nuclear Thought and
Their Implications for Northeast Asia
Van Jackson, professor of International Relations at Victoria University of Wellington.
Abstract
This paper argues that there is no monolithic “United States perspective” on nuclear weapons inNortheast Asia. Instead, the propensity of US policymakers to use nuclear weapons there isheavily conditioned by their political and ideological orientation. Although this may seem
obvious, it means that the US response to change—whether induced by military aggression,
shifts in adversary nuclear policy, or trends in conventional weapons technology, depends
substantially on the internalized causal beliefs about stability of those in power at the time of adecision because events will be interpreted differently by different constituencies within the US
policy community.
Although there has always been a rough ideological divide between nuclear hawks (thosetending to favor military action) and doves (those generally opposing the use of force) in the
United States, the past several decades have seen more diversity in the types of views andpreferences expressed in policy circles about strategic stability and the (dis)utility of nuclear
weapons. Arms-controllers, who are found almost entirely in the Democratic Party today, seek toreduce risks to strategic stability and view advanced conventional weapons as heightening therisks of nuclear use. Nuclear traditionalists exist in both major political parties and accept thelogic of mutually assured destruction (MAD). Nuclear primacists, who are located solely within
the Republican Party, believe stability derives from nuclear superiority, escalation dominance,
and the willingness to launch damage-limiting nuclear first-strikes. And future-of-war (FoW)
strategists, a trans-partisan group, de-center the role of nuclear weapons in US strategy in favorof a focus on precision-guided conventional munitions and delivery systems. These categoricaldistinctions matter because the scope for US nuclear weapons use—and the propensity to engage
in actions that trigger adversary nuclear weapons use—narrows and widens depending on whose
logic and preferences prevail in moments of crisis or shock.

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Prospects for DPRK's Nuclear Use Scenarios and Deterrence
Measures of the US and ROK AllianceSangkyu Lee, assistant professor, Korea Military Academy.
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 US-ROK alliance in theface of the increasingly sophisticated DPRK nuclear threat is examined. Then, the DPRK's
nuclear capabilities and nuclear strategy are investigated, and nuclear use cases are presented indetail 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 civilian casualties. Among the expected cases, it wasevaluated that attacking the ROK Mobile Corps would be the most probable scenario, and thatthe 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 providing
extended deterrence by the United States on the Korean Peninsula to maintain the nuclear
balance are emphasized, therefore, and measures to strengthen the credibility of US extended
deterrence are also suggested.

Avoiding Nuclear War in the Taiwan Strait
Sheryn Lee, senior lecturer in the Division of Leadership at the Swedish Defence University.
Introduction
Since the unresolved ending of the Chinese Civil War (1949), the Communist Party of China’s(CCP) unwavering view has been that Taiwan is a part of China and must be unified with themainland. The delicate status quo that resulted—Taiwan’s de facto status as an independent
nation and the United States’ informal role guaranteeing Taiwan’s security—has led to varying
approaches from Beijing to achieve unification by 2049. Following the establishment of thePeople’s Republic of China (PRC), the use of force was Beijing’s strategy, but a military
campaign by the PRC to invade and control Taiwan in the 1950s was derailed by insufficienttraining and the onset of the Korean War. The two “offshore crises” in 1954/5 and 1958 when
the PRC attacked Taiwan-controlled islands demonstrated Beijing’s willingness to threaten
force. And Beijing’s live-fire exercises during the 1996/7 Taiwan Straits crisis in response tothen-President Lee Teng-hui’s visit to the United States showed China’s willingness to curtail
Taiwan’s creeping democratization.
The ambivalence in China’s no first use of nuclear weapons policy, the deteriorating “strategic
ambiguity” policy of the United States since the Trump administration, and the increasing
identification of Taiwan as an independent polity raises the prospect of conflict over Taiwan. But
the use of nuclear weapons in the Taiwan Straits would happen only under extreme
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circumstances. Beijing is increasing its use of grey zone tactics with conventional and nonmilitary means below the level of nuclear provocation to tip the cross-straits military balance inits favor. Its tactical nuclear weapons are coercive—to prevent Taiwanese political support for adeclaration of de jure independence.
This report will first examine China’s aim to achieve unification with Taiwan via its use of threat
and use of force in both the nuclear and conventional domains with a close examination of thethree cross-strait crises. Second, it will outline the geostrategic and geopolitical rationale forcontinued American support for Taiwan’s de facto independence in an era of US-China
competition. Lastly it will examine the role of Taiwan’s consolidating democracy and how
Taipei responds to Beijing’s coercion. It will then conclude with how the Taiwan Straits case
may affect the possibility of nuclear weapons use in Northeast Asia, including in Japan and on
the Korean peninsula.

Potential Use of Low-Yield Nuclear Weapons in a Korean Context
Eva Lisowski, MIT Nuclear Engineering Graduate and Master’s student at Tokyo Institute ofTechnology.
Abstract
This report explores the potential uses of low-yield nuclear weapons in the context of a possible
conflict on the Korean Peninsula. It starts with a definition of low-yield weapons—typically,
weapons with yields of ten kilotons or less that are designed to be nonstrategic or “tactical”
weapons used with shorter-range delivery systems, prepared for the purpose of attacking troops
or battlefield infrastructure. The paper then reviews the history of United States legislation
regarding low-yield weapons and describes three generic scenarios in which foes possessing lowyield weapons might choose, or not choose, to use them during a military conflict. Examples ofradioactive fallout maps are provided based on HYSPLIT modeling for explosions of 0,3 and 10
kilotons at a location on the Korean demilitarized zone at different times of the year. The
arsenals of low-yield weapons in the states possessing nuclear weapons in Northeast Asia, as
well as the United States, are compared, and seven possible “use cases” for low-yield nuclear
weapons involving the Korean Peninsula are put forward.

U.S. Entry into the Korean War: Origins, Impact, and Lessons
James I. Matray, California State University, Chico.
Abstract
This article describes the reasons for the outbreak of the Korean War and US entry into theconflict. At the end of World War II, the United States and the Soviet Union divided Korea into
two zones of military occupation. Cold War discord between the two nations blocked agreement
to end the division, resulting in formation of two Korean governments each bent on reunification.
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Soviet Premier Joseph Stalin reluctantly supported the Democratic People’s Republic of Korea’s(DPRK) invasion of the Republic of Korea (ROK) on 25 June 1950 after Kim Il Sung persuaded
him that victory would be quick and easy. President Harry S. Truman immediately saw the attack
as the first step in a Soviet plan to use military means to achieve global dominance, but heinitially ordered limited US military intervention, maintaining a prewar policy of qualified
containment in Korea. When the ROK failed to halt the invasion, he sent US ground forces toprevent the Communist conquest of the peninsula. Truman wanted to avoid another world war
and did not consider use of atomic weapons until China intervened. This article concludes that
resumption of the Korean War is unlikely because of the US treaty commitment to defend the
ROK and the weakness of the DPRK.

The Deliberate Employment of U.S. Nuclear Weapons: Escalation
Triggers on the Korean Peninsula
Daryl G. Press, associate professor of Government, Dartmouth College.
Abstract
This paper focuses on the conditions under which the United States might use nuclear weapons
in the context of war on the Korean peninsula. It identifies circumstances that might trigger sucha decision, the purposes of US nuclear use, and the plausible targets of US nuclear strikes.
Attention is focused on the roles that nuclear weapons may continue to play in US military
operations and geopolitical strategy despite US steps to reduce their saliency since the end of theCold War. This paper argues that because the United States (and its allies) have a strong
preference against using nuclear weapons, it would only consider doing so if (1) the mission
being performed via the nuclear strike was of critical importance, (2) the mission could not be
accomplished with sufficient certainty or speed with non-nuclear weapons, and (3) the use of
nuclear munitions significantly increases the probability of mission success. This paper identifies
a range of circumstances that could arise during a war on the Korean Peninsula that might satisfy
all three of these criteria, and it identifies the pathways that are most likely to trigger US nuclear
employment. Examining these conditions can help US allies and other partners identify andresolve disagreements about nuclear employment, enhance deterrence against regional
adversaries, and shed light on the logic driving important decisions about US nuclear force
structure and modernization.

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The Role of Missile Defense in North-East Asia
David Wright, Laboratory of Nuclear Security and Policy, Department of Nuclear Science andEngineering, Massachusetts Institute of Technology.
SummaryThis paper discusses specific types of missile attacks the Democratic People's Republic of Korea(DPRK) might launch in a conflict, and it identifies the key sources of uncertainty that US andallied political and military leaders must take into account in assessing how effective defense
systems might be in stopping these attacks. A key finding is that while missile defenses might beable to blunt some kinds of attacks, the DPRK will have options for retaliatory missile attacks
that can reach their targets despite the presence of defenses, and Pyongyang will know which
options those are. The existence of this second set of cases is crucial for United States and allied
leaders to recognize if they are considering taking actions under the assumption that defenses
will be effective in protecting US and allied populations.

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