Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

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

Humanitarian Impacts of
Nuclear Weapons Use 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 of the
Panel on Peace and Security of Northeast Asia

March 2023

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2iAcknowledgments
This report was prepared by primary authors David F. von Hippel and Eva Lisowski, with
contributions from Peter Hayes, Shatabhisha Shetty, Tatsujiro Suzuki, Fumihiko Yoshida,
Michiru Nishida, and Steve Freedkin.
This report has benefited greatly from advice and input provided by Professor Theodore Postol
and by Dr. Lynn Eden.
The NU-NEA project is funded by Nagasaki University, APLN, the Nautilus Institute, the John
D. and Catherine T. MacArthur Foundation, the New Land Foundation, and the Samuel Rubin
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 foundhere. The authors may be contacted via email at: nautilus@nautilus.org

On the Cover:Top right: Photo of Nagasaki after atomic bombing on August 9, 1945, with statuary from a
destroyed Buddhist temple in the foreground. Photo by Cpl. Lynn P. Walker, Jr., U.S. Marine
Corps, via Wikimedia Commons.
Bottom left: Photo of Hiroshima after atomic bombing on August 6, 1945, with Genbaku(Atomic Bomb) Dome in the background. From Records of the U.S. Strategic Bombing Survey,
via National Archives (United States).
Cover collage and typography by Steve Freedkin.
Copyediting by Maureen Jerrett.

Citation:
RECNA-Nagasaki University, Asia Pacific Leadership Network, Nautilus Institute, "Humanitarian
Impacts of Nuclear Weapons Use in Northeast Asia: Implications for Reducing Nuclear Risk," March
2023, at:
RECNA: https://www.recna.nagasaki-u.ac.jp/recna/bd/files/Year_2_NU-NEA_Report_E_2303.pdf
APLN: https://www.apln.network/projects/nuclear-weapon-use-risk-reduction/humanitarian-impacts-ofnuclear-use-cases-in-northeast-asia
Nautilus Institute: https://nautilus.org/napsnet/napsnet-special-reports/humanitarian-impacts-of-nuclearweapons-use-in-northeast-asia-implications-for-reducing-nuclear-risk/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2iiHumanitarian Impacts of Nuclear Weapons Use in
Northeast Asia: Implications for Reducing Nuclear Risk
Executive Summary
The risk of nuclear war—that is, the risk of attacks carried out by detonating nuclear weapons,hereafter “nuclear weapons use”— as of early 2023 is judged by many observers to be at its
highest since the end of the Cold War. This risk is increasing due to nuclear threat-making
during the Ukraine conflict, the India-Pakistan conflict, the Korean conflict, and the Middle
Eastern conflict. Northeast Asia represents one of four potential flash points where nuclear
weapons might be used for the first time since the last time they were used, on Nagasaki on
August 9, 1945—hereafter called “first use” in this report.1
Northeast Asia includes two nuclear weapons states (China and Russia), a third nuclear weapons
state with a key presence as a guarantor of security (the United States), a fourth and more recent
self-declared, if not universally accepted, nuclear-armed state (the Democratic People’s Republicof Korea, or DPRK), and two non-nuclear weapons nations under the US “nuclear umbrella”
with the technology to produce nuclear weapons and at least some voices arguing for access to or
ownership of nuclear weapons (the Republic of Korea, or ROK, and Japan). Add to this group ofactors the long-simmering and occasionally boiling issue of nuclear weapons on the Korean
Peninsula, tensions over Taiwan, and other regional disputes, and a number of potential nuclear
weapons “use cases” become plausible.
The second year of the Project on Reducing the Risk of Nuclear Weapons Use in Northeast Asia
(NU-NEA), set out to better understand the risks of nuclear weapons use in the region. To thisend, we produced quantitative estimates of the likely direct deaths and delayed cancer deaths
resulting from nuclear weapons use. Five different nuclear "use cases" were simulated andanalyzed. The hypothesized use cases were designed to be plausible, span a range of outcomesfrom a single detonation to limited global nuclear war, and include a range of nuclear actors andtargets initiated in Northeast Asia, involving the Korean Peninsula, and in some cases spreading
to other regions or continents. The estimated deaths and radiation-induced cancers resulting fromthe following six impacts were evaluated:•

Thermal fluence (heat) from nuclear blasts.

•

Firestorms: multiple fires lit by thermal fluence that coalesce into large-area
conflagrations encircled by hurricane-force winds as the heat rising from the fires pulls

1

There is no legal or institutional definition of Northeast or East Asia. The United Nations Economic and Social
Commission for Asia and the Pacific (UNESCAP) uses “East and North East Asia (ENEA) to refer to “China;
Democratic People's Republic of Korea; Hong Kong, China; Japan; Macao, China; Mongolia; Republic of Korea”. See
UNESCAP (undated), “4 List of countries in the Asia-Pacific region and subregions”, available ashttps://data.unescap.org/dataviz/methodology/list-of-countries-in-the-asia-pacific-region-and-subregions.html
An examination of the contested usage related to “Asia” and its sub-regions is found in P. Hayes and C.I. Moon, ed(2018), The Future of East Asia, Palgrave MacMillan, available at: https://link.springer.com/book/10.1007/978981-10-4977-4

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2iii

cooler air in behind it. Physical damage caused by blast overpressure provides fuel for
firestorms, which could burn for weeks.
•

Blast overpressure, causing building damage and collapse.

•

Prompt radiation from the nuclear detonation itself.

•

Fallout radiation, as radioactive material from the blast and contaminated debris are
spread by wind and rain.

•

Radiation-induced cancer deaths suffered by those exposed to prompt and fallout
radiation but not killed by the nuclear blast immediately or in the short term (withinseveral months to a year).

Out of the 30 plausible use cases developed in Year 1 of the NU-NEA project, five use cases
were simulated and evaluated quantitatively:
1. “We’re Still Here” Variant 1, involving nuclear weapons use by the DPRK followed by
the United States, with 3 total detonations of 10 kT (kiloton) and 8 kT weapons.
2. “US Leadership Hubris,” involving first nuclear weapons use by the United States,
followed by use by the DPRK, and China, with 18 total detonations ranging in yield from
8 to 300 kT.
3. “Use by Terrorists” Variant 1, with one 10 kT weapon detonated by a terrorist group.
4. “Conflict from Ukraine Spreads East,” involving first nuclear weapons use by Russia andfollowed by the United States, totaling eight detonations of 8, 150, and 200 kT weapons.
5. “Not Going Well in Taiwan,” involving first nuclear weapons use by China followed byresponses from the United States, with a total of 24 detonations ranging in yield from 8 to
300 kT.
The table below summarizes the estimated prompt and short-term deaths and radiation-induced
cancer deaths resulting from the impacts above for each of the five use cases evaluated. Even in
the most limited of nuclear conflicts, deaths were in the tens or hundreds of thousands, with themore extensive conflicts resulting in millions of deaths and hundreds of thousands of cancer
deaths. It should be noted that even the most extensive conflicts evaluated here were halted shortof an all-out exchange of intercontinental nuclear missile attacks, but certainly could have ended
that way. In the table below, “prompt” deaths are those caused by physical damage or fires in theimmediate aftermath of detonations, including victims not killed immediately but dying withindays or weeks, and “short-term” deaths include victims who succumbed to their injuries within
the year following the nuclear attack.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2iv

Estimated Likely Direct and Cancer Deaths in Each of Five Modeled Use Cases2

These results show that use cases that include many high-yield (50-300 kT) airbursts result in ahigher relative impact, roughly 35% lethality, than use cases with a limited number ofdetonations or with mostly surface-bursts, which average roughly 25% lethality. As a conflict
escalates, especially when progressively larger nuclear detonations target more populated areas,
the humanitarian impacts of a nuclear conflict not only increase, but often grow by orders ofmagnitude. One contributing impact is the occurrence of deadly firestorms resulting from highyield weapons detonated as airbursts that cause far-ranging thermal fluence, demonstrating thatfirestorms can be a significant contributor to the lethality of nuclear weapons. Furthermore, evenuse cases with a limited number of surface-bursts or using weapons of relatively low yield cancause a disproportionately high number of fatalities when acute health effects from highradiation doses and long-term cancer deaths are considered.
In Use Case 3, for example, a single surface-burst in an urban area results in estimated cancer
fatalities on the same order of magnitude as the limited global nuclear war cases shown in Use
Cases 2 and 5. The death toll in the short-term from exposure to high fallout radiation could also
be the same or higher in Use Case 3, even though only one nuclear weapon has been detonated inan urban area. This result emphasizes how unpredictable the long-term and health impacts ofnuclear use cases can be because it is nearly impossible to foresee whether a conflict will end
after one detonation, 18 detonations, 24 detonations, or more, and whether urban areas will betargeted. Even when the conflict does not escalate to global nuclear war, it is possible that
impacts consistent with those expected in a global-scale nuclear war can be felt after only one
nuclear detonation.
In addition to devastating losses of human life, a range of economic and societal impacts, such as
billions of dollars in infrastructure damage and health care costs, and a further set of global,
regional, and local ecological impacts such as climate effects or effects on oceans, would also
result from these use cases. The evaluation of these and other impacts will be addressed in thethird project year.
The use cases evaluated in the NU-NEA project are intended to be plausible, but they capture
only a small fraction of the possible pathways to nuclear war and its consequences identified inthis project, which in turn do not even begin to encapsulate the universe of possible ways that a2Note that Individual impacts in this table may not add up to the exact total shown in column five due to rounding.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2v

nuclear conflict could start and play out. Several conclusions, however, can be drawn from thelimited number of use cases evaluated in this project:•

A nuclear conflict based on regional issues can escalate to a global nuclear conflict within
hours or days after the first use of nuclear weapons.

•

Any nuclear detonations, even in relatively unpopulated areas, are likely to result in atleast thousands of deaths, with possible fallout crossing international borders, causing
additional health risks and increasing political tensions even when fallout levels are low.

•

Even when focused on military targets, nuclear detonations may kill many hundreds ofthousands of people within days or months, as well as cause hundreds of thousands ofadditional cancer deaths and great economic damage.

•The impact of mass fires or firestorms that sometimes result from nuclear explosions cansurpass the lethality of other direct impacts of nuclear use. Historically, military planningfor nuclear use has lacked sufficient consideration of firestorm impacts.

•

Many of the plausible nuclear use cases developed for this project have their genesis in
misinterpretation of intentions and lack of communication between adversaries,
underscoring the need for communication between nations to avert nuclear weapons use,
especially during times of conflict and crisis.

•

There are many plausible pathways to nuclear war that would have cataclysmic effects.
Most of these pathways involve “slippery slopes” of descent into nuclear war, where anaction by one party is misinterpreted by another, leading to conflict escalation thatproceeds further and more rapidly than adversaries intend or foresee. As such, thesepotential pathways to nuclear war are often invisible to policymakers.

•

It is urgent to reduce the risk of choosing or stumbling onto one of these pathways bydeveloping and applying regional and global policy measures such as increasingtransparency of nuclear stockpiles, deployments, and operational and declaratory
doctrine—especially relating to integration of nuclear firestorms into nuclear targeting—such as increasing communications with nuclear hotlines.

•

In addition, it is important to explore policy measures to reduce the role of nuclear
weapons in security policy and to revive arms control and disarmament diplomacy. Suchmeasures include introducing a nuclear no-first threat norm; resolving regional conflicts;
and, ultimately, establishing a regional security framework including denuclearization of
the Korean Peninsula and a nuclear weapon free zone in the region towards eliminationof nuclear weapons altogether.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2viProject Members
Researchers/Report Authors:
David F. von Hippel, Senior Associate, Nautilus Institute for Security and Sustainability
Eva Lisowski, Graduate Student in Nuclear Engineering, Tokyo Institute of Technology
Steering Committee Members:Peter Hayes, Executive Director, Nautilus Institute for Security and Sustainability
Shatabhisha Shetty, Executive Director, Asia-Pacific Leadership Network
Professor Tatsujiro Suzuki, Vice Director, Research Center for Nuclear WeaponsAbolition, Nagasaki University
Professor Fumihiko Yoshida, Director, Research Center for Nuclear Weapons Abolition,
Nagasaki University
Professor Michiru Nishida, School of Global Humanities and Social Sciences, Nagasaki
University
Steve Freedkin, Senior Associate, Nautilus Institute for Security and Sustainability
Nathanial Gronewold, Senior Communications Adviser, Asia-Pacific Leadership
Network
Advisor:
Professor Noboru Takamura, Atomic Bomb Disease Institute, Nagasaki University

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2vii

Table of Contents

Acknowledgments........................................................................................................................... ii
Executive Summary ....................................................................................................................... iii
Project Members ........................................................................................................................... vii
Table of Contents ......................................................................................................................... viii
Table of Figures ............................................................................................................................. xi
Table of Tables ............................................................................................................................. xv
1

2

3

Summary of Results and Provisional Policy Lessons ............................................................. 1
1.1

Summary of use case evaluations..................................................................................... 1

1.2

Initial policy lessons ......................................................................................................... 6

1.3

Project next steps .............................................................................................................. 8

1.4

Contents of subsequent sections of this Report ................................................................ 9

Background: Regional Setting and Project Goals ................................................................. 10
2.1

The risks of nuclear conflict as an increasing concern for our times ............................. 10

2.2

Updated summary of nuclear weapons situation on the Korean Peninsula ................... 11

2.3

Summary of project goals, approaches/methods, and organization ............................... 18

2.3.1

Approaches and methods, by project year .............................................................. 19

2.3.2

Project organization ................................................................................................ 20

Selecting Nuclear Weapons Use Cases for Analysis ............................................................ 21
3.1

4

Summary definitions and applications of use cases ....................................................... 21

3.1.1

What defines a use case?......................................................................................... 21

3.1.2

Applications of use cases ........................................................................................ 22

3.1.3

Objectives in assembling and evaluating a range of use cases ............................... 23

3.1.4

Criteria for selecting use cases for further analysis ................................................ 23

3.2

Use Cases Evaluated ...................................................................................................... 24

3.3

Elaboration of use cases for quantitative evaluation ...................................................... 26

Evaluation of Use Cases—Impacts Considered ................................................................... 27
4.1

Introduction: Impacts of nuclear weapons use ............................................................... 27

4.2

Thermal fluence (radiative heat) .................................................................................... 28

4.3

Firestorms ....................................................................................................................... 30

4.4

Blast overpressure .......................................................................................................... 34

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

viii

5

6

4.5

Prompt radiation exposure ............................................................................................. 38

4.6

Radiation exposure from fallout ..................................................................................... 39

4.7

Delayed health effects from radiation exposure ............................................................. 39

Methods Used to Estimate Impacts of Nuclear Detonations ................................................ 40
5.1

Introduction .................................................................................................................... 40

5.2

Evaluation of thermal fluence impacts ........................................................................... 40

5.3

Evaluation of firestorm impacts ..................................................................................... 42

5.4

Evaluation of blast overpressure impacts ....................................................................... 46

5.5

Evaluation of prompt radiation exposure ....................................................................... 47

5.6

Evaluation of fallout radiation exposure ........................................................................ 49

5.7

Estimation of radiation-induced cancers from exposure to prompt and fallout
radiation dose ................................................................................................................. 52

5.8

Estimation of the aggregate impact of the effects of nuclear detonations ..................... 53

Estimated Fatalities Due to Nuclear Detonation Impacts ..................................................... 57
6.1

Use Case 1: “We’re Still Here” ...................................................................................... 57

6.2

Use Case 2: “US Leadership Hubris” ............................................................................ 61

6.3

Use Case #3: “Use by Terrorists” V1............................................................................. 67

6.4

Use Case 4: “Conflict from Ukraine Spreads East” ....................................................... 71

6.5

Use Case 5: “Not Going Well in Taiwan” ..................................................................... 75

6.6

Conclusion: Overall Summary of Simulated Use case Results and Implications .......... 83

Glossary ........................................................................................................................................ 85
ANNEXES .................................................................................................................................... 89
Annex 1: Nuclear Use Cases Developed During and Subsequent to Project Year 1 fromwhich Evaluated Use Cases Were Selected .................................................................................. 89
Suite of use cases developed during and subsequent to project Year 1, and criteria for
selecting use cases for further analysis .......................................................................... 89
Presentation of use cases ....................................................................................................... 89
New use cases developed after Project Year 1 incorporating lessons from
Ukraine Conflict............................................................................................................. 99“Sending a Message, Eastern Doorstep” .............................................................................. 99“Conflict from Ukraine Spreads East” ................................................................................ 105
Annex 2: Use Case Elaborations................................................................................................. 108
Annex 3: Additional Results of Use Cases Evaluation ............................................................... 114“We’re Still Here” Variant 1 (Use Case 1): ............................................................................ 114

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2ix

Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 1. ......................................................................................................... 114
Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 1 from Different Impacts All Detonations: ................................................................ 117
Nuclear Fallout Simulation Results: Use Case 1 ................................................................ 118“US Leadership Hubris,” Use Case 2: .................................................................................... 119
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 2. ......................................................................................................... 119
Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 2 from Different Impacts All Detonations: ................................................................ 135
Nuclear Fallout Simulation Results: Use Case 2: “US Leadership Hubris” ....................... 136“Use by Terrorist” V1, Use Case 3: ........................................................................................ 138
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 3. ......................................................................................................... 138
Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 3 from Different Impacts. ........................................................................................... 140
Nuclear Fallout Simulation Results: Use Case 3: Nuclear Weapon Use by Terrorists
Variant 1.............................................................................................................................. 141“Conflict from Ukraine Spreads East”, Use Case 4:............................................................... 142
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 4. ......................................................................................................... 142
Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 4 from Different Impacts, All Detonations. ............................................................... 146
Nuclear Fallout Simulation Results: Use Case 4: “Conflict from Ukraine Spreads
East.” ................................................................................................................................... 147“Not Going Well in Taiwan”, Use Case 5: ............................................................................. 148
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 5. ......................................................................................................... 148
Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in
Evaluated Use Case 5 from Different Impacts, All Detonations. ....................................... 164
Nuclear Fallout Simulation Results: Use Case 5: “Not Going Well in Taiwan.”............... 165

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2xTable of Figures
Figure 1-1: Image Depicting the Area Likely Affected by a Firestorm (Orange Shaded Area)
from Evaluated Use Case 2, Response Detonation 2 (Yokohama, Japan). .....................................3
Figure 1-2: Map of Fallout in Asia and North America from Detonations in Evaluated Use
Case 2 (Radiation Dose Units in rem, Time in UTC). .....................................................................4
Figure 2-1: Map of Northeast Asia. ...............................................................................................17
Figure 4-1: Probability of First- through Third-Degree Burns and Radiant Exposure as a
Function of Nuclear Weapons Yield..............................................................................................29
Figure 4-2: Examples of Flash Burns Suffered by Victims of Nuclear Weapons in Japan,
including Burns Suffered through Clothing.................................................................................. 30
Figure 4-3: Schematic of the Initiation and Progress of a Firestorm (or “Superfire”). ................ 32
Figure 4-4: Firestorms Ignited by Nuclear Detonations in Hiroshima, 1945. .............................. 33
Figure 4-5: Variations of Blast Effects of a Nuclear Detonation Associated with Positive and
Negative Phase Pressures with Time. ........................................................................................... 36
Figure 4-6: Impacts of Nuclear Blast on Wood-Framed House at Nevada Nuclear Weapons
Test Site (5 psi) and on a Concrete Building at Hiroshima. ......................................................... 37
Figure 5-1: Opening Screen of Defense Nuclear Agency “Weapon Effects” Program. .............. 41
Figure 5-2: Example of Plot of Thermal Fluence Contours in QGIS: Use Case 2, First Use
Detonation 3 (DPRK). .................................................................................................................. 42
Figure 5-3: Example Image of Potential Firestorm Zone (orange shaded area) in QGIS: Use
Case 2, Response Detonation 2 (Yokohama, Japan). ................................................................... 46
Figure 5-4: Example of Peak Blast Overpressure Contours Mapped in QGIS: Use Case 2,
Additional Detonation 10 (South China). ..................................................................................... 47
Figure 5-5: Example of Prompt Radiation Exposure Contours Mapped in QGIS: Use Case 2,
Response Detonation 1 (Camp Humphries, ROK). ...................................................................... 48
Figure 5-6: Biological Radiation Dose Levels (rem) Used to Visualize and Analyze
HYSPLIT Simulation Results. ...................................................................................................... 49
Figure 5-7: Example Fallout Radiation Exposure Map as Simulated using HYSPLIT and
Projected in QGIS: Use Case 2, Response Detonation 1 (Camp Humphries, ROK). .................. 52
Figure 5-8: Overall Calculation Flow to Estimate the Fatalities caused by Nuclear
Detonations. .................................................................................................................................. 56
Figure 5-9: Nuclear Detonation Fatality Estimation Method based on Blast Overpressure,
Prompt Radiation, and Thermal Fluence. ..................................................................................... 56
Figure 6-1: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting from
Use Case 1, All Detonations. ........................................................................................................ 59
Figure 6-2: Nuclear Fallout Simulation Results for Use Case 1, Radiation Dose Units
in rem. ........................................................................................................................................... 60

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

xiFigure 6-3: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting from
Use Case 2, First Use Detonations. ............................................................................................... 63
Figure 6-4: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting from
Use Case 2, First Use and Response Detonations......................................................................... 64
Figure 6-5: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting from
Use Case 2, All Detonations. ........................................................................................................ 65
Figure 6-6: Fallout Patterns Resulting from First-Use (upper left), First-Use and Response(upper right), and All (lower left) Detonations in Use Case 2. ..................................................... 66
Figure 6-7: A Single, 10 kT Nuclear Detonation in Central Tokyo, Japan, Estimated Likely
Deaths, and Estimated Cancers from Use Case 3. ........................................................................ 69
Figure 6-8: Local and Regional Fallout Patterns Resulting from the 10 kT Surface-burst
Detonation in Use Case 3. ............................................................................................................. 70
Figure 6-9: Targets, Estimated Likely Deaths, and Estimated Additional Cancers from Use
Case 4, First Use Detonations. ...................................................................................................... 72
Figure 6-10: Targets, Estimated Likely Deaths, and Estimated Additional Cancers from Use
Case 4, First Use and Response Detonations. ............................................................................... 73
Figure 6-11: Fallout Patterns resulting from First Use Detonations in Use Case 4. ..................... 74
Figure 6-12: Targets, Estimated Likely Deaths, and Estimated Additional Cancers Resulting
from Use Case 5, First Use Detonations. ...................................................................................... 77
Figure 6-13: Targets, Estimated Likely Deaths, and Estimated Additional Cancers Resulting
from Use Case 5, First Use and Response Detonations. ............................................................... 78
Figure 6-14: Targets, Estimated Likely Deaths and Estimated Additional Cancers Resulting
from Use Case 5, All Detonations. ............................................................................................... 79
Figure 6-15: Fallout Pattens for First Use detonations in Japan and Guam in Use Case 5. ......... 80
Figure 6-16: Fallout Pattens for First Use and Response Detonations in Japan, Guam, andChina in Use Case 5. ..................................................................................................................... 81
Figure 6-17: Fallout Pattens for All Detonations in Asia in Use Case 5. ..................................... 82
Figure A1-1: Nuclear Use Cases Assembled and Considered, and Use Cases Selected for
Analysis......................................................................................................................................... 98
Figure A3-1: Use Case 1, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 114
Figure A3-2: Use Case 1, RD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 115
Figure A3-3: Use Case 1, RD-2, Potential Ranges of Potential Firestorm and Other Likely
Lethal Impacts. ............................................................................................................................ 116
Figure A3-4: Use Case 1, First Use Detonations, Fallout Modelling Results. ........................... 118

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

xii

Figure A3-5: Use Case 1, All Detonations, Fallout Modelling Results...................................... 118
Figure A3-6: Use Case 2, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 119
Figure A3-7: Use Case 2, FUD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 120
Figure A3-8: Use Case 2, FUD-3, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 121
Figure A3-9: Use Case 2, FUD-4, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 122
Figure A3-10: Use Case 2, FUD-5, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 123
Figure A3-11: Use Case 2, RD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 124
Figure A3-12: Use Case 2, RD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 125
Figure A3-13: Use Case 2, AD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 126
Figure A3-14: Use Case 2, AD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 127
Figure A3-15: Use Case 2, AD-3 and AD-4, Ranges of Potential Firestorm and Other Likely
Lethal Impacts. ............................................................................................................................ 128
Figure A3-16: Use Case 2, AD-5, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 129
Figure A3-17: Use Case 2, AD-6, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 130
Figure A3-18: Use Case 2, AD-7, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 131
Figure A3-19: Use Case 2, AD-8, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 132
Figure A3-20: Use Case 2, AD-9, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 133
Figure A3-21: Use Case 2, AD-10, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 134
Figure A3-22: Use Case 2, First Use Detonations, Fallout Modelling Results. ......................... 136
Figure A3-23: Use Case 2, First Use and Response Detonations, Fallout Modelling Results. .. 137
Figure A3-24: Use Case 2, All Detonations, Fallout Modelling Results.................................... 137
Figure A3-25: Use Case 3, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts. ....................................................................................................................................... 138

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

xiii

Figure A3-26: Use Case 3, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts including 0.5 psi impact range (blue circle). ................................................................. 139
Figure A3-27: Use Case 3, Fallout Modelling Results. .............................................................. 141
Figure A3-28: Use Case 4, FUD-1 through FUD-3, Ranges of Potential Firestorm and Other
Likely Lethal Impacts. ................................................................................................................ 142
Figure A3-29: Use Case 4, FUD-4 and FUD-5, Attack on Ships at Sea, Ranges of Likely
Lethal Impacts. ............................................................................................................................ 143
Figure A3-30: Use Case 4, RD-1, Attack on Submarine Base, Range of Potential Firestorm
and Other Likely Lethal Impacts. ............................................................................................... 144
Figure A3-31: Use Case 4, RD-2 and RD-3, Attack on Naval Bases, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 145
Figure A3-32: Use Case 4, Fallout Modelling Results. .............................................................. 147
Figure A3-33: Use Case 5, FUD-1 and FUD-5, Attack on Naval Bases, Japan, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 148
Figure A3-34: Use Case 5, FUD-2 and FUD-3, Attack on Naval Bases, Guam, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 149
Figure A3-35: Use Case 5, FUD-4, Attack on Military Base, Okinawa, Japan, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 150
Figure A3-36: Use Case 5, RD-1, Attack on Missile Site, China, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 151
Figure A3-37: Use Case 5, RD-2 through RD-5, Attack on Missile Sites, China, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 152
Figure A3-38: Use Case 5, RD-6, Attack on Missile Site, China, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 153
Figure A3-39: Use Case 5, RD-7 through RD-10, Attack on Missile Sites, China, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 154
Figure A3-40: Use Case 5, AD-1, Attack on Military Base, ROK, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 155
Figure A3-41: Use Case 5, AD-2, Attack on Military Base, ROK, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 156
Figure A3-42: Use Case 5, AD-3, Attack on Missile Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 157
Figure A3-43: Use Case 5, AD-4, Attack on Missile Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 158
Figure A3-44: Use Case 5, AD-5, Attack on Naval Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 159
Figure A3-45: Use Case 5, AD-6, Attack on Military Base, United States (Alaska), Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 160

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

xivFigure A3-46: Use Case 5, AD-7, Attack on Military Base, United States, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 161
Figure A3-47: Use Case 5, AD-8, Attack on Military Base, United States, Range ofPotential Firestorm and Other Likely Lethal Impacts................................................................. 162
Figure A3-48: Use Case 5, AD-9, Attack on Military Base, Japan, Range of Potential
Firestorm and Other Likely Lethal Impacts. ............................................................................... 163
Figure A3-49: Use Case 5, First Use Detonations, Fallout Modelling Results. ......................... 165
Figure A3-50: Use Case 5, First Use and Response Detonations, Fallout Modelling Results. .. 166
Figure A3-51: Use Case 5, All Detonations, Fallout Modelling Results.................................... 166

Table of Tables
Table 1-1: Summary of Assumptions for Evaluated Use Cases .....................................................5
Table 1-2: Summary of Estimated Deaths and Excess Cancers Resulting from Each of theFive Modeled Use Cases ..................................................................................................................5
Table 3-1: Overview of Parameters for Evaluated Use Cases ......................................................25
Table 4-1: Thermal Fluence Thresholds for Burns with Clothing of Various Types ...................30
Table 4-2: Deaths and Casualties Associated with Different Levels of Overpressure .................37
Table 4-3: Health Effects of Ionizing Radiation Doses ................................................................38
Table 5-1: HYSPLIT Simulation Parameters (italicized, underlined values are variable
based on detonation) .....................................................................................................................51
Table 6-1: Use Case 1 Nuclear Detonation Parameters .................................................................57
Table 6-2: Use Case 2 Nuclear Detonation Parameters .................................................................62
Table 6-3: Use Case 3 Nuclear Detonation Parameters .................................................................68
Table 6-4: Use Case 4 Nuclear Detonation Parameters .................................................................71
Table 6-5: Key Parameters of Detonations for Use Case 5 ...........................................................76
Table A1-1: Summary of Use Cases Considered ..........................................................................90
Table A3-1: Estimated Likely Deaths, Use Case 1......................................................................117
Table A3-2: Estimated Likely Deaths, Evaluated Use Case 2.....................................................135
Table A3-3: Estimated Likely Deaths, Use Case 3......................................................................140
Table A3-4: Estimated Likely Deaths, Use Case 4......................................................................146
Table A3-5: Estimated Likely Deaths, Use Case 5......................................................................164

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2xv

1

Summary of Results and Provisional Policy Lessons

The goal of the project, “Reducing the Risk of Nuclear Weapons Use in Northeast Asia,” (NUNEA) is to prevent the escalation of conflicts in Northeast Asia that could result in the detonationof a nuclear weapon. To achieve this goal, the project aims to develop a better understanding of
events that could lead to a first use of nuclear weapons and the potential outcomes of such
nuclear weapons use. An improved understanding of the possible paths to and impacts of nuclear
weapons use will inform the development and implementation of policies that reduce the risk of
nuclear weapons detonation. Ultimately, our goal is to prevent armed aggression and war, with afocus on preventing any use of nuclear weapons.
In the second year of the NU-NEA project, our focus was on adapting, developing, and applying
methods to quantitatively estimate the impacts of nuclear weapons use. Five nuclear weapons“use cases” defined during and subsequent to the first year of the project were simulated indetail. These use cases each begin with a first use detonation of one or more nuclear weapons in
an attack or counterattack against an opponent and continue with response detonations by one ormore adversaries as the conflict escalates. In some cases, multiple exchanges between several
nations escalate to global nuclear war.

1.1 Summary of use case evaluations
During Year 1 and 2 of the NU-NEA project, a total of 30 plausible nuclear weapons use cases
were developed. The focus of the second year of the project was to quantitatively evaluate five of
these use cases. The fatalities and health effects due to six physical impacts of nuclear
detonations were estimated:•

Thermal fluence, or thermal radiation from the nuclear fireball, depending on the
distance from the fireball and other factors, which causes skin burns to exposed flesh, andcauses combustible materials, such as fuel, building materials, and clothing, to ignite.

•

Firestorms started by the thermal fluence from the nuclear detonation under certain
conditions, with the occurrence and extent of firestorms dictated by weapon yield, heightof burst for the detonation, weather, geographical conditions, the presence or absence offuel for the fire, and other factors.

•

Blast overpressure, the blast wave and hurricane-force-or-greater winds caused by the
explosion, which destroys buildings and other structures, sends debris flying, and shatters
glass windows even at distances far from “ground zero” (the point on the ground whereor over which a weapon detonates).

•

Prompt (or immediate) radiation exposure from the nuclear explosion, reachingaffected people within hundreds of meters to kilometers of ground zero.

•

Radiation exposure from fallout, which occurs as radioactive materials from theweapon itself and contaminated soil and debris are thrust into the air, dispersed, anddeposited downwind.

•

Cancer deaths caused by biological radiation doses acquired from exposure to prompt
radiation, cloudshine (fallout suspended in the air), and groundshine (fallout depositedon the ground).

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

1

Thermal fluence, firestorm, overpressure, and prompt radiation exposure impacts were estimatedby calculating the distance from the point of detonation (ground zero) to “contours” (circles ofdamage) associated with different levels of impact, then estimating the population within eachcontour. To estimate nuclear fallout, HYSPLIT software was used to simulate the dispersion anddeposition of radioactive particles from the nuclear cloud, taking into account the location andtime of each detonation, and using historical wind and precipitation weather data. Cancer deaths
were estimated by counting the population within contours who were not victims of otherdetonation impacts but received below-lethal levels of radiation exposure, then applying astandard dose-response relationship to estimate excess cancers in the lifetime of the exposed
population.
The following summarized example demonstrates how these methods were applied to the usecase entitled “US Leadership Hubris” (Evaluated Use Case #2), in which the United Statesdetonates the first nuclear weapon.
First, the general use case narrative was elaborated into a set of specific detonations to illustrate
the potential outcome of a plausible series of events that might result from a first use of nuclear
weapons by the United States. In this use case, an overconfident US president and his or her
advisors, due to various internal and external pressures, mount a partially successful attack on
nuclear and missile systems in the Democratic People’s Republic of Korea (DPRK). The DPRK
responds with a nuclear missile attack on a US base in the Republic of Korea (ROK) and attacks
on industrial targets in the ROK and in Yokohama, Japan using weapons conveyed by DPRK
military units. Further response by the United States, in the form of attacks on the DPRK,
inadvertently drags China into the conflict, which leads to nuclear attacks on both Chinese andAmerican homeland soil.
For each of three detonation phases—first use, response use, and additional use—summing to a
total of eighteen locations attacked with nuclear weapons, contours for the lethal and sub-lethallevels of each of the above impacts were modeled and overlayed on maps in QGIS software.
Figure 1-1 shows the likely extent of the firestorm resulting from one of the detonations, andFigure 1-2 shows the map of fallout results from all of the detonations in this use case.
Depending on the weather patterns at the time of detonation, the resulting fallout in Use Case 2
could cover the entirety of the Korean Peninsula, and even reach regions uninvolved in theconflict, such as Southeast Asia and the Caribbean Sea.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 22

Figure 1-1: Image Depicting the Area Likely Affected by a Firestorm (Orange ShadedArea) from Evaluated Use Case 2, Response Detonation 2 (Yokohama, Japan).

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

3

Figure 1-2: Map of Fallout in Asia and North America from Detonations in Evaluated Use
Case 2 (Radiation Dose Units in rem, Time in UTC).
A summary of the five use cases evaluated during the second year of the NU-NEA project isprovided in Table 1-1. The yields of the weapons used are shown in kilotons (kT). The five use
cases range from cases with a single detonation or just a few detonations, resulting in a limited
nuclear conflict, to cases with a first-use, response, and additional detonations totaling up to 24
total nuclear attacks in what becomes a global nuclear conflict.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

4

Table 1-1: Summary of Assumptions for Evaluated Use Cases
Evaluated Use Case

First
User

Responding
User(s)Weapon Sizes

Total
Detonations#1: “We’re Still Here”
Variant 1

DPRK

United States

10 kT (fission), 8 kT (2-stage
H-bombs)

3#2: “US Leadership Hubris”

UnitedStates

DPRK, China

20 and 10 kT (fission), 8, 50,
200, and 300 kT (2-stage Hbombs)

18#3: “Terrorist” Variant 1

Terrorist[None]

10 kT (fission)

1#4: “Conflict from Ukraine
Spreads East”

RussiaUnited States

2-stage H-bombs, 150, 200
kT, and 8 kT

8#5: “Not Going Well in
Taiwan”

China

United States,
China

8, 50, 250, and 300 kT (2stage H-bombs)

24

Table 1-2 summarizes the estimated likely deaths and excess cancers resulting from alldetonations in each use case, with the impacts of potential firestorms and high radiation dosefrom fallout indicated separately. These results show that firestorm and fallout impacts cansignificantly increase the death toll of a nuclear war. Depending on the weapon yield, height ofburst, weather patterns, time of day, and burnable material in the blast area to fuel firestorms,
death tolls may vary significantly, but tragic levels of deaths are a certainty. Although the total
number of detonations in each use case spans from one to 24 detonations, the results vary widely
regardless of the number of detonations. Depending on the decisions leaders make in times ofcrisis, such as what types of targets to attack and when, the resulting death toll could vary widelyand cannot be reliably predicted.

Table 1-2: Summary of Estimated Deaths and Excess Cancers Resulting from Each of theFive Modeled Use Cases11Note that Individual impacts in this table may not add up to the exact total shown in column five due to rounding.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

5

In addition to the impacts evaluated in Table 1-1, the economic and social impacts of nuclear
weapons use are also crucial to consider when discussing solutions to avoid nuclear weaponsuse. Economic and social impacts not yet evaluated include, but are not limited to:•

The health impacts of nuclear detonation and radiation exposure.

•

The infrastructure rebuilding following nuclear detonation.

•

The environmental contamination with radioactivity.

•

The ecological damages at global, regional, and local levels such as nuclear winter,acidification of oceans, and other impacts.2•

The social and political consequences of nuclear use.

Some of these topics will be taken up by the NU-NEA project in its upcoming third year.

1.2 Initial policy lessons
Although Year 2 of the NU-NEA project was largely devoted to the quantitative assessment of
the potential impacts of nuclear weapons use in the region, some initial policy conclusions fromthe evaluations of use cases described above include:•

The range of use cases evaluated shows the potential for a nuclear conflict based onregional issues—such as DPRK nuclear weapons issues or Taiwan policies—to escalate
to a nuclear global conflict within hours or days.

•

Any nuclear detonations, even in relatively unpopulated areas, are likely to result in atleast thousands of deaths, thus even at the more restrained end of the spectrum of
possibilities, potential nuclear weapons use represents a humanitarian, political, andsocial tragedy.

•Radioactive fallout from nuclear detonations can cross borders, and sometimes fall on
populations hundreds or thousands of kilometers from the original target of a detonation.
These populations may well be in nations or even regions not involved in the conflict thatspawned nuclear weapons use, and thus justifiably incensed at being put at risk. As such,and even though the doses of radioactivity received in those locations may be low, evenlimited nuclear exchanges have the potential to cause social, political, and health impacts
far beyond the borders of the combatants. It thus behooves potential users of nuclear
weapons to take into account potential impacts of weapons use on populations andnations distant from the immediate attack zones, as those far-flung impacts may wellhave unintended social and political consequences for nuclear weapons users.
Conversely, the potential spread of radiation to distant places—again, even if in low
concentrations—means that nations seemingly not associated with potential conflicts

2

As just one example of such impacts, a recent article explores the effect of nuclear war on wild-caught fish stocks,
both in the context of how changes in climate from nuclear conflict might affect fisheries and how fisheries might
be affected by increased use of wild-caught fish to replace food supplies where agriculture is affected by the
impacts of nuclear war. Kim J. N. Scherrer, Cheryl S. Harrison, Ryan F. Heneghan, Eric Galbraith, Charles G.
Bardeen, Joshua Coupe, Jonas Jägermeyr, Nicole S. Lovenduski, August Luna, Alan Robock, Jessica Stevens,
Samantha Stevenson, Owen B. Toon, and Lili Xia (2020), Marine wild-capture fisheries after nuclear war”, PNAS,
November 24, 2020, vol. 117, no. 47, available as www.pnas.org/cgi/doi/10.1073/pnas.2008256117

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

6have a vested interest in cooperating to defuse those conflicts before they “go nuclear.”As such, non-nuclear nations, including those that have established their own nuclear
weapons-free zones, could reasonably claim the right and responsibility to work to reduce
the risk of nuclear weapons use, just as do nuclear weapons states. Non-nuclear nations,based on the threat of fallout from distant detonations, may also demand moretransparency in nuclear weapons deployment, and more accountability from nuclear
weapons states for potential impacts of weapons use.
•

Many nuclear detonations, even when focused on military targets, have the potential tokill hundreds of thousands of people within the following days, weeks, and months, cause
hundreds of thousands of additional long-term (years or decades) cancer deaths, andcause economic damage that would likely be in the tens of billions of dollars or more,adding economic misery as an additional cost of these humanitarian disasters.

Policy lessons related to potential firestorms ignited by attacks with nuclear weapons include:•

The potential impacts of mass fires/firestorms can, for some targets and detonations,
outstrip the lethality of other direct impacts of nuclear use, but historically they have had
little consideration in military planning for nuclear use.

•

It is clear that the radius of firestorm lethality will exceed the radius of lethal/near-lethal
damage from other effects (overpressure, radiation, thermal fluence) in many possible
nuclear attacks.

•

Many, possibly all nuclear “targeteers”—those individuals and organizations responsiblefor identifying, setting, and justifying potential targets for nuclear weapons—have nothistorically considered the impacts of firestorms properly and thus underestimate theimpacts of nuclear weapons use.

•

If firestorm effects are properly considered, the impact of all nuclear weapons above theminimum size at which firestorms are created could be much larger than originally
expected.

•

Nuclear war planners and targeteers may argue the legality of using nuclear weapons
with yields (and/or targets) below the "firestorm threshold.” They must, however, now
confront the fact that nuclear targeting today using weapon-and-target combinations thatspawn firestorms cause greater damages than the direct physical and radiological impactsof the weapons themselves. These greater damages make such nuclear weapons use
irrefutably contravene international humanitarian law (proportionality, military necessity,
civilian principles) due to the firestorm effects for which most targeteers neglect toaccount.

Most of the nuclear use cases evaluated in this report, as well as most of the use cases developedin Year 1 of this project but not evaluated quantitatively, have their genesis in misinterpretationof adversaries’ intentions and lack of communication between adversaries. Nuclear weapons use
is thus instigated at least in part by adversaries misunderstanding each other’s intentions, actions,or statements as posing a military threat, including interpreting words or deeds as being threats ofnuclear use. This commonality underscores that:•

Nations must communicate their intentions, particularly their military intentions (forexample, regarding military exercises and missile tests) to adversaries to avoid situations
where actions are unintentionally misinterpreted as attacks or impending attacks.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

7•Communications between nuclear states, and between those groups responsible fornuclear weapons deployment in nuclear states, must be built or rebuilt if adequate
channels do not now exist, and must be maintained no matter what issues arise to erode
political relations.

•

There are many plausible pathways to nuclear war that would have cataclysmic effects.
Most of these pathways involve “slippery slopes” of descent into nuclear war, where anaction by one party is misinterpreted by another, leading to conflict escalation thatproceeds further and more rapidly than adversaries intend or foresee.

•

It is urgent to reduce the risk of choosing or stumbling onto one of these pathways bydeveloping, agreeing on and implementing policy measures such as:o Increasing transparency of nuclear stockpiles, deployments, and operational anddeclaratory doctrine—especially relating to integration of nuclear firestorms into
nuclear targeting; ando Increasing communications via the development/recommitment to the use of
nuclear hotlines and revived arms control and disarmament diplomacy.

•

In addition, it is important to explore policy measures to reduce the role of nuclear
weapons in security policy and revived arms control and disarmament diplomacy, suchas:o Introducing a nuclear no-first threat norm3; resolving regional conflicts; ando Establishing a regional security framework including denuclearization of the
Korean Peninsula and establishment of a nuclear weapon free zone in the region
as steps towards elimination of nuclear weapons altogether.

1.3 Project next steps
Some of the expected next steps in the NU-NEA project, to be addressed in the third project
year, include:•

Developing and applying methods for analysis of selected additional impacts of nuclear
detonations, such aso Cost of infrastructure rebuildingo Cost of environmental contamination with radioactivity
o Costs of ecological damageo Social and political consequences

3

No First Use is a well-established norm (often called the “nuclear taboo”) although only some nuclear weapons
states have adopted it as declaratory policy (China 1964, India 1998). “No First Threat” is a concept for a possible
parallel norm that aims to establish a set of threats to use nuclear weapons that are so clearly illegal in terms ofspecificity as well as likely illegal due to disproportionality, military non-necessity, and transgression of the civilian
targeting principle that would result from the threatened nuclear weapons use that all nuclear weapons and nonnuclear weapons states should be able to agree that such threats should not be made, ever, and if made, would beprosecutable under international law. In general, international law prohibits the threat and use of force. How such
injunctions apply to nuclear weapons threats and use is contested. This project has commissioned an expert studyof nuclear weapons threats and related norms to ascertain the validity and soundness of the concept of No First
Threat, to be completed in 2023.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

8•Identify additional policy lessons learned from conducting the NU-NEA project.

•

Develop policy options that minimize the risk of nuclear weapons use and the role ofnuclear weapons in security policies.

1.4 Contents of subsequent sections of this Report
The remainder of this Report is organized as follows:•

Section 2 briefly reviews the background of the project, including the nuclear weapons
situation in Northeast Asia and a summary of project goals and approaches.

•

Section 3 provides a summary 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, and lists the subset of use cases developed under the project, carried out by
a range of state and non-state actors, that has been selected for quantitative analysis inYear 2 of the NU-NEA project.

•

Section 4 describes the nuclear detonation impacts evaluated quantitatively during thesecond year of the project, including thermal fluence (heat), “firestorms” that can result
from some nuclear attacks, blast overpressure, exposure to prompt radiation from nuclear
detonations and from fallout, and excess cancer deaths implied by radiation exposures.

•

Section 5 summarizes the methods used for use case analysis and quantitative estimationof fatalities resulting from selected direct impacts.

•

Section 6 details the estimated fatalities and cancers in the affected population resulting
from nuclear detonation impacts in each of the five evaluated use cases.

Following the main sections of this report, a Glossary that includes the definitions of terms andacronyms is provided, along with Annexes that include summaries of the NU-NEA project use
cases, more detailed descriptions of the use cases chosen for analysis, and additional quantitative
results and maps related to the use cases evaluated.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

92

Background: Regional Setting and Project Goals

2.1 The risks of nuclear conflict as an increasing concern for our times
In our Year 1 Report, published in January 2022,4 we noted that the risk of nuclear war—that is,
the risk of attacks carried out by detonating nuclear weapons, hereafter “nuclear weapons use”—
was at its highest since the end of the Cold War.5 Although it was difficult, at the time, todetermine how the world could move close to the brink of nuclear use without actually goingover the edge, by December of 2022 world events had, in fact, taken the globe and the Northeast
Asia region to an even higher level of nuclear anxiety. Since early 2022, Russia’s invasion ofneighboring Ukraine, described by Russia as a “special military operation,” has led toconcerns—fed by comments by Russian President Vladimir Putin and the West’s interpretationof same—that Russia might choose to use tactical nuclear weapons in Ukraine.
Western nations (the European Union, the United States, and others) have responded to Russia
actions in Ukraine with economic sanctions against Russia and specific Russian political andbusiness leaders. In addition, they have provided tens of billions of dollars in military andeconomic aid to Ukraine to support its defense of its territory. How the conflict in Ukraine has
unfolded has not escaped the attention of actors in Northeast Asia,6 and although the ways in
4

RECNA-Nagasaki University, Asia Pacific Leadership Network, Nautilus Institute (2022), Possible Nuclear Use Cases
in Northeast Asia: Implications for Reducing Nuclear Risk, NAPSNet Special Reports, January 27, 2022, available ashttps://nautilus.org/napsnet/napsnet-special-reports/possible-nuclear-use-cases-in-northeast-asia-implicationsfor-reducing-nuclear-risk/. Also available from the APLN and RECNA websites, respectively as
https://apln.network/projects/nuclear-weapon-use-risk-reduction/final-report-year-1 andhttps://www.recna.nagasaki-u.ac.jp/recna/bd/files/Year_1_NU-NEA_Report_E_2201281.pdf?utm_source=CPB&utm_medium=cms&utm_campaign=JRD27735
5The “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, was just, as of this writing,
set at 90 seconds before midnight, the closest it has ever been to that symbol of pending nuclear threat. See Bill
Chappell (2023), “The Doomsday Clock moves to 90 seconds to midnight, signaling more peril than ever”, dated
January 24, 2023, and available at https://www.npr.org/2023/01/24/1150982819/doomsday-clock-90-seconds-tomidnight. Even before the events of 2022 caused the Bulletin to further advance the Doomsday Clock towardmidnight, the Bulletin’s Science and Security Board condemned the Russian invasion of Ukraine, saying, in part,“[f]or many years, we and others have warned that the most likely way nuclear weapons might be used is throughan unwanted or unintended escalation from a conventional conflict. Russia’s invasion of Ukraine has brought thisnightmare scenario to life, with Russian President Vladimir Putin threatening to elevate nuclear alert levels andeven first use of nuclear weapons if NATO steps in to help Ukraine. This is what 100 seconds to midnight looks like”(Bulletin Science and Security Board, 2022, “Bulletin Science and Security Board condemns Russian invasion of
Ukraine; Doomsday Clock stays at 100 seconds to midnight”, Bulletin of the Atomic Scientists, dated March 7, 2022,
and available as https://thebulletin.org/2022/03/bulletin-science-and-security-board-condemns-russian-invasionof-ukraine-doomsday-clock-stays-at-100-seconds-tomidnight/?utm_source=ClockPage&utm_medium=Web&utm_campaign=DoomsdayClockMarchStatement.
6
The potential implications of the Ukraine conflict on nuclear weapons policies and postures among the nations ofNortheast Asia and beyond are provided from the point of view of each nation in a series of Nautilus Institute
Policy Forum papers and have also been published on RECNA and APLN websites. These papers include CHEON
Myeongguk (2022), "Implications of the Ukraine War for ROK Security", NAPSNet Policy Forum, December 05,
2022, available as https://nautilus.org/napsnet/napsnet-policy-forum/implications-of-the-ukraine-war-for-roksecurity/; Anastasia Barannikova (2022), "Potential Implications of the Situation in Ukraine for Russia’s Nuclear

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

10which political and military leaders will ultimately reflect the lessons of Ukraine into nuclear
policy have yet to be fully determined, events and leader statements thus far in 2022 make it
clear that potential conflicts still have great potential to trigger either planned or accidental use of
nuclear weapons in the region. The DPRK’s “new nuclear doctrine” and some of China’s mostrecent statements about Taiwan have certainly increased concerns over potential nuclear
weapons use in the region. As we noted in our Year 1 NU-NEA Report, even the first use of only
one 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 so much uncertainty that global catastrophic war would be a distinct
possibility. The memory of the horrific loss of life and catastrophic 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 the same time, nuclear arsenals continue to grow,and nuclear “deterrence” remains a key part of military 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 allpolicymakers in maintaining international peace and security.7

2.2 Updated summary of nuclear weapons situation on the Korean Peninsula
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 DPRK—and two non-nuclear
weapons states with large nuclear power programs and advanced technological prowess in the
ROK 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.”8 The
definition of Northeast Asia for the purposes of this Report includes Taiwan (Chinese Taipei), as
it is regularly in the news, particularly following the conflict in Ukraine, as a flash point forpotential conflict without which any consideration of nuclear use cases in the region would beincomplete.
In addition to these Northeast Asia (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 third great power with nuclear weapons in the region, the United States. The
Deployment in Northeast Asia", NAPSNet Policy Forum, November 07, 2022, available ashttps://nautilus.org/napsnet/napsnet-policy-forum/potential-implications-of-the-situation-in-ukraine-for-russiasnuclear-deployment-in-northeast-asia/, Paul K. Davis (2022), “Potential Implications of the War In Ukraine forNortheast Asia”, NAPSNet Policy Forum, October 27, 2022, available as https://nautilus.org/napsnet/napsnetpolicy-forum/potential-implications-of-the-war-in-ukraine-for-northeast-asia/; Tong Zhao (2022), “Implications of
Russia’s Nuclear Signaling During the Ukraine War for China’s Nuclear Policy”, NAPSNet Policy Forum, October 13,
2022, available as https://nautilus.org/napsnet/napsnet-policy-forum/implications-of-russias-nuclear-signalingduring-the-ukraine-war-for-chinas-nuclear-policy/; and Alexandre Y. Mansourov (2022), “Birds of a Feather:Thoughts on Pyongyang’s Lessons from the War in Ukraine", NAPSNet Policy Forum, October 07, 2022, available ashttps://nautilus.org/napsnet/napsnet-policy-forum/birds-of-a-feather-thoughts-on-pyongyangs-lessons-from-thewar-in-ukraine/
7
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/
8
See, 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.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

11United States has a number 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, with updates from the descriptions
provided in our Year 1 project report, are provided below. 9•

China is thought to possess approximately 350 to 400 nuclear weapons, based on recent
estimates,10 with delivery systems including short and long-range land-based missiles(including intercontinental ballistic missiles, or intercontinental ballistic missiles(ICBMs), that can be fired from fixed or mobile launchers, ballistic missile submarines,
missiles based on ships, and bombers.11 Most or all of these weapons are thought to be
strategic nuclear weapons, that is, not developed for tactical or battlefield use. The
expansion of China’s nuclear forces has been underway in recent years, underscored byreports of large-scale development of what are thought to be new missile silos for ICBMs
in Xinyang and Gansu provinces.12 Starting in 1964, and ending, at least nominally,13
with its signing of the Comprehensive Nuclear Test Ban Treaty (CTBT) in 1996, China isestimated to have conducted forty-seven nuclear tests, of which twenty-three were aboveground.14•

Russia possesses over six thousand nuclear weapons, of which 4500 are reported to be
operational15 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 1500 non-strategic (tactical)

9

For an overview of nuclear capabilities of regional powers, see P. Hayes, T. Kulkarni, C.I. Moon, S. Shetty (2022),
WMD in Asia-Pacific, Asia-Pacific Leadership Network for Nuclear Non-Proliferation and Disarmament, available ashttps://cms.apln.network/wp-content/uploads/2022/03/WMD-in-Asia-Pacific.pdf
10See, for example, Idrees Ali and Phil Stewart (2022), “China likely to have 1,500 nuclear warheads by 2035:
Pentagon”, Reuters, dated November 29, 2022, and available as https://www.reuters.com/world/china-likelyhave-1500-nuclear-warheads-by-2035-pentagon-2022-11-29/ ; the Federation of American Scientists (2022),“Status of World Nuclear Forces, available as https://fas.org/issues/nuclear-weapons/status-world-nuclear-forces/;
and RECNA (2022), “List of World Nuclear Warheads (June 2022), (世界の核弾頭一覧（2022 年 6 月）),available as https://www.recna.nagasaki-u.ac.jp/recna/nuclear1/nuclear_list_202206
11
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
12
See, 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
13
Recent low-yield nuclear tests are suspected, but not proven, to have been carried out recently by China. See,for example, 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-haveconducted-low-level-nuclear-test-us-report-claims
14
Atomicarchive.com (2021), “China’s Nuclear Tests,” available as https://www.atomicarchive.com/almanac/testsites/prc-testing.html
15
See, for example, Hans M. Kristensen and Matt Korda (2022), “Russian nuclear weapons, 2022,”
Bulletin of the Atomic Scientists, Volume 78, 2022, Issue 2, Pages 98-121, published online 25 February 2022, andavailable as https://www.tandfonline.com/doi/pdf/10.1080/00963402.2022.2038907?needAccess=true

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

12nuclear weapons in addition to its mostly high-yield strategic warheads.16 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
missiles that it has test-fired multiple times during 2022.17 The DPRK has on manyoccasions announced its development and possession of nuclear weapons through its state
media outlets and other channels. These announcements notwithstanding, the actual sizeof the DPRK’s nuclear weapons arsenal is not known with any certainty. Analysts
suggest the DPRK may possess sufficient fissile material for on the order of fifty nuclear
weapons, although only a fraction of that material may have been incorporated into
warheads as of 2021.18 The DPRK has conducted six known nuclear weapons tests
between 2006 and 2017.19 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’s delivery systems aremostly land-based, including a recently-demonstrated capability to fire ballistic missiles
from a train, but the DPRK may also be developing the capability to fire ballistic
missiles, and potentially nuclear ballistic missiles, from submarines.20•

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 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 US extended nuclear
deterrence.21 Although the nuclear umbrella is not a formal legal or treaty commitment,
rather a “political assurance,” it has sufficed thus far, along with national laws and moral
positions born out of being the only nation in history to have suffered a nuclear attack, tokeep Japan and other “umbrella” states from developing nuclear weapons. That said, andas indicated in one of the use cases presented in our Year 1 Report, Japan certainly does
have the technical wherewithal to develop nuclear weapons, probably in a matter of

16

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).
17
See, for example, Carlotta Dotto, Brad Lendon and Jessie Yeung, “North Korea’s record year of missile testing is
putting the world on edge”, CNN, dated December 26, 2022, available ashttps://www.cnn.com/2022/12/26/asia/north-korea-missile-testing-year-end-intl-hnk/index.html
18
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/
19
Nuclear Threat Initiative (2020), “North Korea,” last updated October 2020, and available ashttps://www.nti.org/learn/countries/north-korea/
20
Korda (2021), ibid.
21
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.”

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

13months, in the unlikely event that concerns about the reliability of the US nuclear
umbrella rise to the level that might lead it to do so. Such a breakout likely would be an
abrogation of its obligations as a signatory to the Treaty on the Non-Proliferation of
Nuclear Weapons (NPT). The late Shinzo Abe, Japan’s former prime minister, following
the Russian invasion of Ukraine in February of 2022, suggested the discussion of a
NATO-style “nuclear sharing” approach for Japan, which raised concerns in China andelsewhere, although the nuclear sharing option was quickly rejected as unacceptable byJapan’s current prime minister, Fumio Kishida.22 Japan has both small-scale uranium
enrichment facilities (used to produce low-enriched uranium)23 and a full-scale
reprocessing plant (at Rokkasho), still waiting for an operating license to separate
plutonium for use in “mixed oxide” reactor fuel. And, most importantly, Japan has
ownership of over 45 tonnes of separated plutonium (Pu), of which 9.3 tonnes are instorage in Japan, with the rest in Europe and the United Kingdom (14.8 tonnes in France
and 21.8 tonnes in the United Kingdom).24 The amount of Pu in storage in Japan alone issufficient to make on the order of a thousand or more nuclear warheads.25•

The ROK is also covered by US extended nuclear deterrence, is a signatory of the NPT,and is thus also unlikely for those reasons to develop nuclear weapons, although theelection of a more pro-nuclear (energy and weapons) government in 2022, headed byPresident Yoon Suk Yeol, has intensified the debate over whether the country should
acquire nuclear weapons, with remarks by President Yoon in early 2023, althoughdescribed as discussing only a hypothetical scenario, raising the profile of the discussionof nuclear weapons acquisition by the ROK.26 The ROK, unlike Japan does not possess,
as a condition of its nuclear energy agreement with the United States, either facilities foruranium 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 inclandestine 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 the22

See, for example, Sayuri Romei (2022), “The legacy of Shinzo Abe: a Japan divided about nuclear weapons”,
Bulletin of the Atomic Scientists, dated August 24, 2022, available as https://thebulletin.org/2022/08/the-legacyof-shinzo-abe-a-japan-divided-about-nuclear-weapons/; and Justin McCurry (2022), “China rattled by calls forJapan to host US nuclear weapons”, The Guardian, dated 1 Mar 2022, and available as
23
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
24Japan Atomic Energy Commission (2022), The Status Report of Plutonium Management in Japan—2021 Office ofAtomic Energy Policy, Cabinet Office, dated July, 12, 2022, and available as
http://www.aec.go.jp/jicst/NC/sitemap/pdf/kanri220712_e.pdf
25Assumes 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
26
See, for example, William Gallo (2023), “Why South Korea’s President is Talking About Nuclear Weapons”, Voiceof America, dated January 16, 2023, and available as https://www.voanews.com/a/why-south-korea-s-presidentis-talking-about-nuclear-weapons/6919962.html

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

14considerations that led the DPRK’s to begin its pursuit of nuclear weapons.27 The ROK,
like Japan, is highly advanced technologically, and there is little doubt that it could
produce nuclear weapons-capable technologies quite rapidly, in the 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 officiallya state—a signatory to the NPT or related agreements, it has said that it will abide by
those agreements.28 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.”29•

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.30 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 1967.31 The United States continues toproject nuclear deterrence for the ROK and for the region as a whole from submarines,
ships, bombers, and missiles based elsewhere, including on US territory and from basesin Japan and elsewhere. The United States has a full range of nuclear missile
technologies, including missiles designed for both tactical and strategic delivery of27

Anastasia Barannikova (2022), “Korean Peninsula Nuclear Issue: Challenges and Prospects”, Journal for Peaceand Nuclear Disarmament, Volume 5, 2022 - Issue sup1: Reducing the Risk of Nuclear Weapons Use in Northeast
Asia, dated 20 March, 2022, and available ashttps://www.tandfonline.com/doi/full/10.1080/25751654.2022.2053409
28
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/
29
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/
30
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
31
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/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

15

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.”32 The United States, however, withdrew from the INF
treaty in 2019, and implied that it might deploy intermediate cruise missiles in the AsiaPacific Region,33 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 2-1, showing the distance from thedemilitarized zone (DMZ) dividing the nations of the Korean Peninsula, the key (but not theonly) locus of conflict in the region.34

32

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
33
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
34
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.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

16

Figure 2-1: 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 for

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

17nearby populations, including plumes of radioactive material capable of causing acute andchronic health impacts, depending on factors such as distance and dilution.35
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 weaponsuse, 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, thelongstanding state of war—albeit restrained for nearly 70 years by an Armistice to the point that
it is now a “cold peace”—on the Korean Peninsula, make reduction in the risk of nuclear
weapons detonation a key goal for our time.

2.3 Summary of project goals, approaches/methods, and organization
The overall goal of the “Reducing the Risk of Nuclear Weapons Use in Northeast Asia” projectcontinues to be the reduction and minimization of the risk that nuclear weapons will be used in
Northeast Asia. To achieve this goal, the project is designed to assist in developing better
understandings of the processes that could lead to the first use of nuclear weapons and thepotential outcomes of such nuclear weapons use. Improved understandings of the potential paths
to and impacts of nuclear weapons use will help to inform the development and implementationof policies designed to reduce the risks of nuclear weapons detonation. To repeat, our strategic
goal 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 weapons be used (with or without intention) in
NEA and by whom? How might such first use of nuclear weapons escalate to a larger
scale of nuclear war? And which states might respond to a first nuclear 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 weapons use in
NEA?
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?
Step 1 of this process, the development of nuclear use cases involving, though not necessarily
restricted to the Korean Peninsula, was the focus of our Year 1 Report, and has continued in year
2 with the addition of three more cases created based on consideration of changes that the
Ukraine conflict has brought about.
35

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 ashttps://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/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

18

It should be emphasized that in developing these nuclear use cases—which represent only asmall sampling of the vast universe of possible ways that nuclear conflict could start andevolve—we do not intend in any way to imply that one use case is more likely than another—which is unknowable—or to unintentionally will any of these use cases even one iota closer toreality. Our intention, rather, is and has been to posit these cases to learn from them and by sodoing, anticipate and avoid such outcomes.
In Year 2 of the NU-NEA project, our focus has been on the evaluation of the results of selected
use cases, focusing on the fatalities caused by blast overpressure, heat, and, to an approximate
extent, by the firestorms that history indicates will result from nuclear use (Nagasaki andHiroshima in 1945, but also the extensive bombing of cities during World War II) and will
outstrip the damage caused by blast overpressure and thermal radiation alone. We also track the
immediate (prompt) and longer-term (from fallout) radioactive emissions caused by eachdetonation in each of the selected use cases and estimate their effects on human health. Use cases
evaluated were selected to span a range of places, nuclear actors, detonation types, and extents ofnuclear conflict.
As noted above, the overall goal 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 is being 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 analysis are defined to take place between
2025 and 2030.
2.3.1

Approaches and methods, by project year

With the above questions in mind, the project 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, which was the focus inproject Year 1, and the results of which are provided in the Year 1 Report was to develop
multiple cases that involve possible and plausible nuclear weapon use in the region,
including possible escalation to a larger scale of nuclear war through counterstrikes, andretaliation, with a focus on use cases involving the Korean Peninsula in a regional andglobal geo-strategic context. Given the global context, some posited cases involve actual
weapons use in places other than the Korea Peninsula. The objective of our Year 1 work
was to provide enough specificity in the definition of the use cases to sufficiently informthe estimates of the impacts of those cases to allow modeling of the cases to move
forward during the second year of the project.
2. Simulation of nuclear use cases. This second task, undertaken in Year 2 and describedin this report, has been to develop computer simulations, including the use of the
HYSPLIT tool for estimating the movement and severity of radioactive fallout,36 and
36

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/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

19other analysis, including of blast overpressure and heat emissions in the seconds
following nuclear detonation. These calculations have been applied to selected examplesof the nuclear use cases assembled during task 1 above, with each of the selected cases
first elaborated to provide the specific inputs—timing, weapon type and yield, height ofweapon burst, and other parameters—needed to undertake quantitative analyses.
Although it has not been possible to elaborate and model all of the use cases developed inYear 1, the goal of Year 2 has been to assess the potential consequences of nuclear use
cases spanning a range of places, nuclear actors, detonation types, and extents of nuclear
conflict. Task 2 includes evaluating selected key nuclear impacts quantitively, including
the areas affected directly by nuclear detonations, the areas affected by radioactive
fallout, and the human casualties and radiation health impacts implied by thosequantitative results, while identifying a range of other possible consequences, for which
qualitative discussions of impacts and/or descriptions of the methods available to further
evaluate those impacts, including, for example, economic and environmental damages,
and the possible climate impacts of nuclear use, some of which will be addressed in Year
3 of the project.
3. Development of policy recommendations to reduce the risk of nuclear war in NEA.
Based on the results of task 1 and 2, above, 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.
2.3.2

Project organization

The Research Center for Nuclear Weapons Abolition, Nagasaki University (RECNA), Nautilus
Institute, 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, Nautilus Institute, and APLN have set up a
Steering Committee as a project management organization. PSNA serves as an Advisory Groupto the Project, and key members of PSNA are involved in each task. A Consultative Group of
experts in various disciplines related to the project was assembled to provide input to and review
of use cases in Year 1, with some Consultative Group members also commissioned to prepare
background papers, published on the websites of the project partners, to inform the development
and analysis of nuclear weapons use cases. In Year 2 of the project, contributing authors werecommissioned to provide input to a synthesis paper (in process as of this writing) on the impactof the Ukraine conflict on nuclear postures and policies in Northeast Asia. Some of thesecontributions have been published on the project partners’ websites as short papers.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

20

3

Selecting Nuclear Weapons Use Cases for Analysis

3.1 Summary definitions and applications of use cases
3.1.1

What defines a use case?

For the purposes of this project, and as described in our Year 1 Report, a “use case” is defined as
starting with the detonation of one or more nuclear weapons in an attack or counterattack against
a military opponent. As such, this definition 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 isto provide deterrence of a potential 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 purposessuch as civil engineering, as has been discussed in the past, tested in many instances (by theUnited States and the Soviet Union) but actually carried out (by the Soviet Union) in only ahandful of cases.39
Nuclear use cases as defined in this project follow the general considerations, as described in ourYear 1 Report, that the detonations will occur between 2025 and 2030, and that they will involve(if not necessarily start on) the Korean Peninsula. For the purposes of impact modeling and otheranalyses, attributes for each use case were specified including:
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?
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 night40) and type of detonation?
39

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
40
To model dispersion of radioactive particles from a nuclear use incident, it has been necessary to specify both alocation and approximate timing to obtain weather data representative of the time and place of weapons use. The
same information is needed to calculate other modeling results, for example, human exposure.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

21

•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?41•

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?
•

To pose cases that are of relevance to policymakers, they should be judged to bepossible within the universe of all possible nuclear use cases in the region, and•They should have a large enough potential impact — in terms of human lives lost,
economic damage, political repercussions, environmental and/or ecologicaldamage — to capture the interest of policymakers.
3.1.2

Applications of use cases

In their paper prepared for in Year 1 of this project, Paul K. Davis and Bruce Bennett list thefollowing applications of use cases:42•“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

41

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, although incorporation of these details has in part been beyond the scope of thework in project Year 2.
42
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 2

22

•

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.
3.1.3

Objectives in assembling and evaluating a range of use cases

History, as we noted in our Year 1 Report, is strewn with events that failed to be considered bythose 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” forreasons varying from the events being thought to be “unlikely” to the foibles of human hubris.
As such, the goal of this project has been to initially assemble as broad a range of use cases as ispracticable. Given the many actors in NEA, and the almost limitless number of potential triggers
for conflict in the region, there are literally an unlimited number of use cases that might havebeen produced. Limits on the amount of time and human resources that can go into developing,and subsequently, as in the Year 2 analyses reported on below, evaluating such use cases meanthat only a limited set of use cases can be assembled and analyzed. Our objectives in doing sohave been to assemble a set of use cases that includes all of the potential actors in the use of
nuclear weapons in NEA in general and involving the Korean Peninsula in particular, that
include multiple modes of nuclear weapons use, for example, against different types of targets, indifferent types of detonations, and at different levels of yield, and to explore a range of triggering
events. The objective in assembling and, subsequently, analyzing this breadth of use cases is to
identify and test policy solutions that reduce the risk of nuclear war from a range of different
angles in order to find policy solutions that can be used to address—and are “robust” responses
to—different ways in which nuclear war might arise.
To analyze the use cases, again mindful of both the time and other resources required to carry out
use case evaluation, we selected a subset of the 27 use cases and use case variants developed
during Year 1, plus one of the three additional use cases (and variants) developed this year with
Russia as the first user (see Annex 1), for further analysis during Year 2.
3.1.4

Criteria for selecting use cases for further analysis

Criteria in selecting this group of use cases were that the group of cases selected as a wholeshould:•Include a range of first users of nuclear weapons.

•

Include a range of targets of nuclear weapons use—military, urban, rural—although inpractice most of the nations that might be first users would likely, given existing
doctrines for nuclear weapons use, attack military targets. Note, however, that many
military targets in NEA are surrounded by civilian areas.

•

Include a range of extents of nuclear conflict (single detonation, limited exchange,
extensive exchange).

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

23•Include multiple delivery systems, heights of burst, and sizes (nuclear yield) of weapons,
although the former may not be as important in determining the results of detonations.

•

Be sufficiently limited to allow analysis within the constraints of project resources, and to
avoid significant repetition of analyses of individual detonations.

With these criteria in mind, NU-NEA project staff and leaders reviewed summaries of the 30 use
cases assembled and settled on a set of use cases to move forward to quantitative and otherfurther analyses.

3.2 Use Cases Evaluated
Based on application of the criteria above, five use cases were selected for quantitative analysis
in Year 2 of the NU-NEA project:•“We’re Still Here” Variant 1, in which the DPRK used nuclear weapons first (evaluatedas Use Case 1).

•“US Leadership Hubris” in which the first use of nuclear weapons is by the United States(evaluated Use Case 2).

•“Terrorist” Variant 1, in which a terrorist attack is the first (and in this case, only) use of
nuclear weapons (evaluated as Use Case 3).

•“Conflict from Ukraine Spreads East “in which Russia carries out the first use of nuclear
weapons (evaluated as Use Case 4).

•“Not Going Well in Taiwan”, in which China detonates the first weapon of the conflict(evaluated as Use Case 5).

Full descriptions of these use cases are available in the Year 1 Report or in Annex 1 to thisReport, and summaries are provided in Table 3-1. In this table, and in the text and graphics
shown in sections below, “FUD” stands for “First Use Detonations,” attacks with nuclear
weapons by first users, “RD” stands for “Response Detonations,” and “AD” stands for“Additional Detonations.”

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

24

Table 3-1: Overview of Parameters for Evaluated Use Cases
Evaluated
Use Case#1: “We’re
Still Here”
Variant 1

First
User

DPRK

Responding
User(s)United States

Types ofTargets

WeaponTypes/Sizes

FUD:”Demonstration”
Target in ROK

FUD: Fission,
10 kT

RD: DPRK
NuclearInfrastructure
FUD: DPRK
nuclear weapons
infrastructure#2: “USLeadership
Hubris”

UnitedStates

RD: US militarybase in ROK,DPRK, China
ROK/Japan
industrial targets
AD: US andChinese military
targets#3:“Terrorist”
Variant 1#4: “Conflictfrom
UkraineSpreads
East”#5: “Not
Going Wellin Taiwan”

Terrorist

Russia

RD: Fission,
20, 10 kT

18

AD: 2-stage Hbombs 50,
200, 300 kT
FUD: Fission,
10 kT

FUD: US militarybases in Japanand warships at
United States sea
RD: Russian
naval andsubmarine bases

FUD: 2-stage
H-bombs, 150,
200 kT[None]

3

FUD: 2-stage
H-bombs, 8 kT

FUD: Transit andcommercial hub in
Tokyo

FUD: US militarybases in Japan
and Guam
China

RD: 2-stage Hbombs, 8 kT

Total
Detonations

RD: H-bomb, 8
kT

1

8

FUD: 2-stage
H-bombs, 250
kT

United
RD: ChineseStates, China military targets

RD: 2-stage Hbombs, 8 and
50 kT

AD: US militarybases, Chinese
military bases

AD: 2-stage Hbombs 250,
300 kT

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

24

25

3.3 Elaboration of use cases for quantitative evaluation
Descriptions of the five selected use cases listed above were elaborated to provide inputs for themodeling in project Year 2, including:•

Developing the narrative of each use case describing in greater detail how the use caseplays out.

•

Stipulating the yields of the weapons used (in kilotons, or kT) and the height of burst(HOB—point of detonation of the weapon either above the ground or at or slightly below
ground level), in meters. These details were developed based on consideration of factors
such as weapons arsenals reportedly held by each actor, the nature of the target of eachdetonation, and assumptions as to how those planning a nuclear attack on each particulartarget might do so. Weapons yield and HOB were stipulated for each first use detonation(FUD), response detonation (RD), and additional detonation (AD) included in the Use
Case.

•

Defining the precise targets (expressed as latitude/longitude coordinates) for eachdetonation.

•

Deciding a precise date and time for each detonation to enable the use of historical
weather data,43 such as the wind speed and direction that would carry radioactive
particles downwind (nuclear fallout), the air transparency at the time of the detonation,
which affects the distance that thermal radiation can travel, and other parameters.

•

Identifying the type of weapon and delivery system used, including whether the weapon
is a fission, thermonuclear, of hybrid weapon to specify the “fission fraction” of thedetonation for the purposes of determining prompt and fallout radiation.

The results of these elaborations are provided in Annex 2: Use Case Elaborations to this Report.

43

There is, of course, no guarantee that the weather on, for example, March 1, 2026, will be the same as recordedon March 1, 2021. As such, there is considerable and unavoidable uncertainty as to which direction fallout from anuclear detonation will travel, and the extent to which it will affect any given location. This uncertainty cannot be
fully avoided, but sensitivity analysis considering other possible/probable weather patterns in selected locations
can help to identify when and where fallout impacts might be particularly significant.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

26

4

Evaluation of Use Cases—Impacts Considered

4.1 Introduction: Impacts of nuclear weapons use
Nuclear weapons detonations have a wide range of destructive impacts on humans, structures,the environment, and society. Some of these impacts occur within seconds or minutes—orindeed, fractions of a second—while some take days, months, years, decades, or even longer tofully manifest. It would be impossible to catalog and evaluate all of these impacts, but we haveattempted to prepare quantitative estimates of a range of key impacts of the nuclear detonationsin the use cases described above, with additional impacts receiving qualitative treatment, andsome left for further analyses in Year 3 of the NU-NEA project.
The physical impacts of nuclear weapons detonation, with a focus on human casualties, include:•

Thermal fluence, or thermal radiation from the nuclear fireball, depending on the
distance from the fireball and other factors, causes skin burns to exposed flesh, andcauses combustible materials, from fuel to building materials to clothing, to ignite.

•

The damage from potential firestorms started by the thermal fluence from the nuclear
detonation. Although the thermal fluence from nuclear explosions sets fires at various
distances by causing combustible materials to burn, and additional fires can stem frombuildings and vehicles destroyed by overpressure, firestorms are a special case in thatthey represent an entire area lit aflame essentially at once, creating gale-force winds inthe direction of the fire/ground zero in all direction, burning for hours, and nearly
impossible to escape or survive.

•

Blast overpressure, the blast wave from the explosion, destroys buildings and otherstructures, with destruction complete near “ground zero” (the point on the ground atwhich or over which a detonation occurs) and decreasing with distance. People andanimals within the blast wave area are typically killed or injured as buildings collapse andby flying debris.

•

Prompt (or immediate) radiation exposure from the nuclear explosion, reachingaffected victims within ranges of hundreds of meters to kilometers of ground zero in amatter of seconds.

•

Radiation exposure from fallout as radioactive materials from the blast are lifted into
the air, dispersed, and deposited downwind. Severe radiation exposure from fallout
occurs within a few hours to days following a nuclear detonation, and typically nearground zero, but radioactive materials can travel downwind for tens or even hundreds ofkilometers, and exposure can continue for months as the decay of radioactive elements
occurs in fallout zones.

•

Human health impacts result from exposure to both prompt radiation and nuclear
fallout. Severe exposure can be lethal in a matter of hours to weeks or inhibit the healingof burns and physical injuries by weakening the human immune system. Less severeradiation exposure can cause autoimmune illnesses and cancer, which often appears years
or decades after exposure.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

27

Each of these impacts have been evaluated quantitatively during Year 2 of the NU-NEA project.
Discussions of each of these impacts are provided in the remaining subsections of this section,
the methods used to evaluate each of these impacts are described in Section 5 of this Report, andthe results of the applications of those methods are presented in Section 6.
Except for fallout radiation dispersed by wind, the direct impacts of nuclear detonations overlap
to simultaneously affect populations in the areas around ground zero. An individual exposed tosevere radiation levels may also suffer physical injuries and/or burns or be trapped in a firestorm
zone. Those whose immune systems are weakened by radiation exposure are more susceptible tosuccumbing from overpressure-related injuries or burns, and burn injuries inhibit the healing ofother physical injuries.
Additional impacts of nuclear detonations on humans, society, the economy, and theenvironment result from the direct impacts described above. These include:•

The economic costs of deaths and health impacts of nuclear detonation and radiation
exposure, starting with the costs of treating the sick and injured, but also including otherrelated costs to the economy.

•

The costs of infrastructure rebuilding following a nuclear detonation.

•

The costs of environmental contamination with radioactivity.

•

The costs of ecological impacts of nuclear detonations.

•

The potential impacts of nuclear detonations on global climate.

•

The social and political consequences of nuclear use.

These impacts are not addressed directly in this Report, but some of these impacts will be
evaluated in Year 3 of the NU-NEA project, subject to ongoing decisions about Year 3 activities.
Year 3 of the project will, as noted above, focus on identification of policies for reducing the riskof nuclear weapons use.

4.2 Thermal fluence (radiative heat)
Thermal fluence measures the radiative heat from the nuclear fireball resulting from detonation.
Thermal fluence is typically measured in units of calories per square centimeter (cal/cm2) ofsurface area at specific distances or “ranges” from ground zero. Heat radiation from a nuclear
detonation, as noted above, can burn skin, fuel, fabric, flammable building materials, and otherfuels encountered in the line of sight from the nuclear blast. With respect to impacts on humanhealth, thermal fluence of about 8 to 10 cal/cm2 , for the range of nuclear weapon yields
considered in the use cases above, will cause third degree burns on exposed skin in essentially all
individuals not taking evasive action, with 5 to 7 cal/cm2 causing second degree burns, as shownin Figure 4-1.44 Wood will ignite at 10-20 cal/cm2, many fabrics will ignite at 10 cal/cm2, andpaper ignites at around 5 cal/cm2, with ignition depending on conditions including the presenceor absence of humidity or wind. Thermal fluence can have a range of impacts, depending on, forexample, how a person is dressed. Sufficiently high thermal fluence values can cause significant
burns even through heavy clothing, as described in Table 4-1, which focuses on burn thresholds
44

Figure is from page 565 of the seminal 1977 US Department of Defense publication, The Effects of Nuclear
Weapons, 3rd Edition, compiled and edited by Samuel Glasstone and Philip J. Dolan, available ashttps://www.osti.gov/servlets/purl/6852629

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 228

for soldiers equipped with various types of uniforms.45 Examples of burns suffered by the
nuclear bombings in Japan in 1945 are shown in Figure 4-2.46

Figure 4-1: Probability of First- through Third-Degree Burns and Radiant Exposure as a
Function of Nuclear Weapons Yield.

45

From Carl A. Curling and Samantha Todd (2017), Parameters for Estimation of Casualties from First and Third
Degree Flash Burns, institute for Defense Analysis, dated March 2017, and available ashttps://apps.dtic.mil/sti/pdfs/AD1123338.pdf
46
Images from https://www.atomicarchive.com/media/photographs/human/medical.html (left) and fromhttps://www.archives.gov/files/research/military/ww2/photos/images/ww2-164.jpg (right). The latter image also
appears in Glasstone and Dolan (1977), ibid.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

29

Table 4-1: Thermal Fluence Thresholds for Burns with Clothing of Various Types

Figure 4-2: Examples of Flash Burns Suffered by Victims of Nuclear Weapons in Japan,
including Burns Suffered through Clothing.

4.3 Firestorms
A nuclear detonation in any area where fuels are present will start fires. Potential fuels for fires
include wood used in construction, plastics, rubber, fabric, vegetation and other biomass, andstores of combustibles at scales ranging from gasoline cans in garages and automobile fuel tanks
to huge fuel storage tanks at depots. In some cases, these fires will be started by thermal fluence
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 230

from the nuclear blast at many different, dispersed points, and burn out in those areas. In somecases, large fires will be started by thermal fluence, and, driven by ambient winds and/or
topography, grow in a particular direction. Line fires, as are common in forest fires and as
occurred in some of the historic urban fires of the past,47 are an example of this type of
conflagration. The nuclear attack on Nagasaki in August of 1945 created a mass fire when thehills surrounding the city, with relatively little fuel of their own to burn, acted as a constraint on
the fire area and as a flue, with hot air rising from the fire pulling cooler air from the ocean
behind it, and driving the fire up the slope through the city.
Firestorms are also mass fires but have particular characteristics. In a firestorm, a large enoughcontiguous area is set aflame, effectively at once, that the fire creates its own wind patterns. As
heat from the fire rises, winds arise on all sides traveling toward the fire, sometimes at gale-force
velocities of up to 90 miles per hour (about 40 meters/second). In some cases, the generation of afirestorm may be prevented by the surrounding geography. For example, although the fires
resulting from the attack on Nagasaki were devastating, the large-scale firestorm effect was
mitigated by the mountainous geography of the region. Figure 4-3 shows how firestorm windcirculation patterns arise and are perpetuated as the firestorm proceeds.48 These winds both act asa limit to the growth of the fire—although secondary blazes can start outside the fire area fromembers of the firestorm—and cause the fierce, and for all practical purposes, impossible toescape, nature of the firestorm. The thermal fluence from a nuclear weapons detonation can, if
atmospheric, fuel loading, and topographic conditions are suitable, cause mass fires to start in amatter of minutes. Firestorms can burn out an entire area many square kilometers in extent in amatter of hours and are essentially impossible for humans trapped inside the fire zone to escapeor survive. Even if some within the firestorm are able to retreat to, for example, protected subbasements or subway tunnels, the combination of the intense heat from the fires above, as it
penetrates down, coupled with the consumption of oxygen and smoke and toxins from burningmaterials, would cause even those who escaped the initial flames to perish in hours or days.

47

Examples of such line fires include “…the great urban fires that destroyed London (1666), Chicago (1871), and
San Francisco (1906)….,” as well as more recent first such as those that have caused devastation in the North
American west and in many other places in recent years. See, for example, Lynn Eden (2004), Whole World on Fire:
Organizations, Knowledge, & Nuclear Weapons Devastation, Cornell University Press, Ithaca and London (quote
shown is from page 28 of this volume).
48
Source of this information and Figure 4-3 is Theodore A. Postol (1986), “Possible Fatalities from Superfires
Following Nuclear Attacks in or near Urban Areas,” paper included (pages 15-72) in The Medical Implications of
Nuclear War, Fred Solomon and Robert Q. Marston, Editors, National Academies Press, available fromhttps://nap.nationalacademies.org/catalog/940/the-medical-implications-of-nuclear-war
The description of the schematic in Postol’s paper reads, “The drawings show how a mass fire that bums
simultaneously over a large area can generate high ground winds. In A, buoyantly rising air from a fire zone
pushes air at higher altitudes upward and outward. Eventually this action can result in the establishment of amacroscopic flow field of enormous power and extent (B). If the heat output per unit area from combustion is
reduced, but the area over which the heat output is produced is increased, such a large circulating pattern might
still occur. Thus, predictions of ground winds and air temperatures from mass fires must consider both the scale ofthe fire and the heat input per unit area in the region where such fires bum.”

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

31

Figure 4-3: Schematic of the Initiation and Progress of a Firestorm (or “Superfire”).
The city of Hiroshima, when attacked with nuclear weapons in August of 1945, was a city on arelatively flat plain, made up of houses made mostly of wood. The thermal fluence from thenuclear weapon detonated over the city, coupled with the results of the blast overpressure, caused
a firestorm to a radius of about 1.5 to 2 km from ground zero, destroying virtually everything
within that radius (see Figure 4-4).
In many cases, depending in part upon factors such as weapons yield and topography, thecasualties from a nuclear detonation-caused firestorm will effectively overwhelm and subsume
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

32the impacts on people of overpressure, thermal fluence, and initial radiation, as well as fallout,
although all of these impacts combine to reduce survivability. The importance of firestorms to
the overall impacts of nuclear weapons is shown in the results of some of the use cases evaluatedin this report (see section 6), but has often been omitted in past simulation studies of nuclear
detonations.
Fires outside the firestorm radius may still be set due to overpressure and/or thermal damage to
gas and electric infrastructure or ignition of building materials or vehicle or fuels, causing
additional damage.

Figure 4-4: Firestorms Ignited by Nuclear Detonations in Hiroshima, 1945. 49
Firestorms ignited by nuclear detonations are qualitatively different in their initiation from those
ignited by conventional weapons. World War II featured a number of devastating fires,deliberately set by combatants though aerial bombardment in order to destroy war industry
49

Source of image, Atomicarchive.com, available ashttps://www.atomicarchive.com/media/photographs/hiroshima/image-17.html
Caption of image in source: “The ruins of Hiroshima. Almost all wooden houses to a radius of 4,750–6,330 feet
(1,450–1,930 meters) from the hypocenter were crushed instantly. Fire then swept through them, either from theheat of the blast or from cooking fires, until they were engulfed by the firestorm.”

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 233

infrastructure and, perhaps at least equally, to demoralize opponents. Some of these fires also
became firestorms. Although firestorms were ignited in the non-nuclear bombing of cities during
World War II, those firestorms were caused by targeted application of thousands of highexplosive bombs and incendiary devices from hundreds of planes, and thus present a very
different situation relative to the firestorm damage that can be caused by a single nuclear
weapon.
Consideration of firestorm damage has in the past been largely omitted from weapons
damage/targeting analysis by official United States military planners, and likely by planners
from other nuclear nations as well. These omissions have potential international legal
implications, as noted briefly in section 1.2 of this Report.
This omission has been brought to the attention of the public through the work of Lynn Eden,50
Theodore Postol, and others. The work of Lynn Eden and Theodore Postol builds in part on
decades of work by H. L. Brode and his colleagues, who explored the physics of firestorms fromthe 1950s through the 1990s.51

4.4 Blast overpressure
Blast overpressure denotes a shock wave, propagated from the nuclear blast and traveling at
approximately the speed of sound, that causes physical destruction. Although humans are
surprisingly resilient to overpressure, structures are not, and the shock wave from the nuclear
detonation reaches a structure, typically in a matter of seconds, many structures will be
destroyed, depending on their composition and distance from ground zero. When these structures
fail, fatal and non-fatal injuries to persons in and near them result.
A publication on emergency planning and response to a nuclear detonation developed by a US
federal inter-agency committee (led by National Security staff and the Office of Science andTechnology Policy) provides the following description of the blast effects of a nuclear
detonation:52“Initially, blast causes the most casualties in a ground level urban nuclear explosion. Blast
effects consist of overpressure and dynamic pressure waves ... The human body isremarkably resistant to overpressure, particularly when compared with rigid structures suchas buildings. Although many would survive the blast overpressure itself, they will noteasily survive the high velocity winds, or the crushing injuries incurred during the collapseof buildings from the blast overpressure or the impact of high velocity shrapnel (e.g., flying
debris and glass) ... Blast injuries, such as lung and eardrum damage, will likely be
50

Lynne Eden (2004), ibid.
As just one example of Brode’s extensive work, see H.L. Brode, Ph.D., and R.D. Small (1986), “A Review of the
Physics of Large Urban Fires,” paper included (pages 73-95) in The Medical Implications of Nuclear War, Fred
Solomon and Robert Q. Marston, Editors, National Academies Press, available fromhttps://nap.nationalacademies.org/catalog/940/the-medical-implications-of-nuclear-war
52
United States National Security Staff Interagency Policy Coordination Subcommittee for Preparedness &Response to Radiological and Nuclear Threats (2010), Planning Guidance for Response to a Nuclear Detonation,
2nd Edition, dated June 2010, and available ashttps://nepis.epa.gov/Exe/ZyPDF.cgi/P100C9X6.PDF?Dockey=P100C9X6.PDF. A new Third Edition of the same
document, published in May of 2022 by the (US) Federal Emergency Management Agency (FEMA) is available ashttps://www.fema.gov/sites/default/files/documents/fema_nuc-detonation-planning-guide.pdf
51

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

34

overshadowed by injuries related to collapsing structures. Many of these will be fatal
injuries [in the areas of moderate to severe building damage]. Further out [from groundzero], flying debris injuries will prevail ... Large windows can break at blast wave pressures
as low as 0.1 psi, and people will be subject to injury from the glass falling from damaged
tall buildings.”
Units given for overpressure are typically pounds per square inch (psi) at distances or “ranges”
from ground zero. In SI units, one psi is equal to approximately 6.9 kPa (kilo Pascals), and one
Pa is defined as one Newton (N) of force per square meter. Overpressures of 10 psi generate
maximum wind speeds of nearly 300 miles per hour (480 km per hour), or on the order of two or
more times higher than peak wind speeds experienced in even the most violent typhoons andhurricanes. Depending on the distance from ground zero, the pressure wave and hurricane-force
winds will arrive seconds to minutes after the detonation and last for fractions of a second toseconds depending on the weapon yield. The initial pressure wave is followed by a negative
phase pressure, as depicted in Figure 4-5.53 Table 4-2 summarizes the deaths and casualties
associated with different levels of overpressure.54 Figure 4-6 shows examples of destruction from
nuclear blast overpressure on a typical house built to test blast effects at the US nuclear test sitein Nevada and on a concrete building in Hiroshima.55

53

Figure from Chapter 3 of U.S. Army, Navy, and Air Force (1996), FM 8-9, NATO Handbook on the Medical Aspects
of NBC Defensive Operations AMedP-6(B), dated 1 February 1996, and available ashttps://nuke.fas.org/guide/usa/doctrine/dod/fm8-9/1ch3.htm
54
Table from Atomicarchive.com (undated), “Overpressure,” and available ashttps://www.atomicarchive.com/science/effects/overpressure.html
55
Images from Atomicarchive.com, https://www.atomicarchive.com/media/photographs/blast-wave/index.html
and https://www.atomicarchive.com/science/effects/blast-effects-humans.html

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

35

Figure 4-5: Variations of Blast Effects of a Nuclear Detonation Associated with Positive
and Negative Phase Pressures with Time.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

36

Table 4-2: Deaths and Casualties Associated with Different Levels of Overpressure

Figure 4-6: Impacts of Nuclear Blast on Wood-Framed House at Nevada Nuclear
Weapons Test Site (5 psi) and on a Concrete Building at Hiroshima.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 237

4.5 Prompt radiation exposure
Prompt radiation is nuclear radiation occurring within the first minute after a nuclear detonation(as opposed to fallout, which occurs later). The primary radiation types emitted are gamma andneutron radiation, the energy from which is absorbed in tissues and causes damage depending on
the dose of radiation received.56
Units for prompt radiation dose thresholds are often given in rem (“Roentgen equivalent man”),
with one rem equal to 0.01 Sievert (Sv) or 10 millisievert (mSv).57 58 A dose of 200 rem or moreis considered fatal or near-fatal, with doses between 50 and 200 rem considered high but
survivable, and doses of 10-50 rem potentially causing medium- and long-term health impacts,
as shown in Table 4-3.59

Table 4-3: Health Effects of Ionizing Radiation Doses60
Dose (rem)

0.1

5

10

50

100

200

600

1000

Significance

USNRC
annual dose
limit to the
publicUSNRC annual
dose limit forradiation
workers

Statisticalincrease incancer incidence

Considered highdose by USNRCHigh dose with highsurvivability

Survivalchance highly
dependent on
medical care

Almost no
survival evenwith intense
medical care

Lethalwithin days

Onset of cancer

Acute radiation
symptoms

Moderatedecrease in whiteblood cell countSevere decrease in white blood
cell count,
Skin hemorrhage/blood spot,
hemorrhage, infection, hair loss

Diarrhea,
fever, fatal
electrolyte
imbalance

Symptoms
Possible
Death occurs
within2-12 weeks

Cause ofDeath

1-6 weeks

Hemorrhage, Infection<2-14 days

Circulatory,
respiratory
collapse

Compressed Graphic to be inserted into thereport56

See, for example, Atomicarchive.com (undated), “Nuclear Radiation,” available ashttps://www.atomicarchive.com/science/effects/radiation.html
57
In this Report we have used a mixture of SI units (International System of Units) such as Sieverts, and non-SI
units such as rem or pounds per square inch (psi) for overpressure. We do so because much of the literature on
nuclear blast effects, and thus many of the examples of such effects, dates back to research commissioned by theUnited States military in the latter half of the 1900s, and we felt that retaining these units makes is easier tocompare our methods and results with those from the older literature.
58
The online Encyclopaedia Britannica (2022), in https://www.britannica.com/technology/sievert, describes thesievert (Sv) as a “…unit of radiation absorption in the International System of Units (SI). The sievert takes into
account the relative biological effectiveness (RBE) of ionizing radiation, since each form of such radiation—e.g., Xrays, gamma rays, neutrons—has a slightly different effect on living tissue. Accordingly, one sievert is generally
defined as the amount of radiation roughly equivalent in biological effectiveness to one gray (or 100 rads) ofgamma radiation.” One Gray, in SI units, is the absorption of one Joule of radiation energy per kilogram of matter.
59
See also Atomicarchive.com (undated), “Radiation Effects on Humans”, available ashttps://www.atomicarchive.com/science/effects/radiation-effects-human.html
60
Source of Table 4-3: Glasstone and Dolan (1977), ibid, Table 12.108, p. 580.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

38

4.6 Radiation exposure from fallout
Radiation exposure to fallout comes from nuclear materials/contaminated debris sent airborneand deposited downwind by the nuclear detonation. Fallout exposure, measured in the same units
and with the same overall health consequences per unit dose as those for prompt radiation,
above, comes from a combination of materials suspended in the atmosphere (cloudshine) andmaterials deposited on the ground and other surfaces (groundshine). Airborne nuclear materials
are transported by ambient winds and deposited as dry particles or combined with precipitation.
As is the case with prompt radiation, though with greater potential impacts due to the distancesthat airborne radiation from nuclear detonations can be transported, exposures above backgroundlevels, such as exposures below 5 rem/50 mSv may have limited health impacts but significant
political impacts, particularly when international cross-border contamination is considered.

4.7 Delayed health effects from radiation exposure
In addition to the prompt lethal and near-lethal effects of high doses of radiation exposure
described in Table 4-3, lower doses of radiation increase the risk of developing certain cancers,
often many years or even decades after exposure. Tissues at the highest risk of developing
radiation-induced cancers are bone marrow, female breasts, salivary glands, and the thyroid,
while the bladder, colon, stomach, liver, lung, kidney, ovaries, and skin are at a moderate risk ofradiation-induced cancer.61 There is a statistical increase in cancer incidence in a population thathas absorbed a radiation dose of at least 10 rem (0.1 Sv). Below 10 rem, the linear-non-threshold(LNT) model hypothesizes that there is also a per Sv increase in cancer incidence in a
population. Whether or not, however, exposures below 10 rem increase the individual risk ofradiation-induced cancer is a matter of continued debate.62 In this project, it was assumed thatradiation-induced cancer incidence can be estimated in populations that receive a dose of 10 rem
or higher.

61

See, for example, Fred A Mettler (2012), “Medical effects and risks of exposure to ionising
Radiation,” Journal of Radiological Protection. 32 (2012) N9–N13, available fromhttps://pubmed.ncbi.nlm.nih.gov/22395124/
62
The International Commission on Radiological Protection (ICRO) defines the Linear-non-threshold (LNT) model as“A dose-response model which is based on the assumption that, in the low dose range, radiation doses greater thanzero will increase the risk of excess cancer and/or heritable disease in a simple proportionate manner.” ICRP (2007),
Annals of the ICRP PUBLICATION 103, The 2007 Recommendations of the International Commission on RadiologicalProtection, Editor J. Valentin, available as https://journals.sagepub.com/doi/pdf/10.1177/ANIB_37_2-4

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2395

Methods Used to Estimate Impacts of Nuclear Detonations

5.1 Introduction
The direct effects of nuclear weapons described in Section 4—prompt radiation, thermal fluence,
overpressure, and fallout—and their physical impacts scale based on the yield, type of weapon,
and the height of burst of the detonation. The extent of firestorms is determined by thermal
fluence and conditions on the ground at the site of detonation. The level of radioactivity anddistribution of fallout from each detonation depends on the detonation parameters and on
weather conditions. For the most part, these impacts occur within seconds to days of the time ofdetonation, and have overlapping areas of effect, with the exception of biological radiation dose
health effects from prompt and fallout radiation, which cause cancer over a period of years or
decades.
To evaluate the potential consequences of five use cases, we first calculated the extent of various
levels of impact for each detonation and displayed the results on maps. Then, population
databases and geographic information systems (GIS) mapping software were used to estimate thenumber of people exposed to each level of physical impact. To estimate excess cancer risk andthe number of resulting cancer deaths, a cancer incidence factor was applied based on the levelof radiation exposure to the population.
Our primary objective has been to estimate the number of short-term deaths and the number oflong-term radiation-induced cancer deaths resulting from the detonations in each use case. Thisgrim task was undertaken to illustrate the significant impacts that nuclear conflicts, whether
limited or extensive, would have on human populations and to show why the risks of suchconflicts must be minimized.
In the rest of Section 5, the procedures used to quantitatively estimate the impacts of nuclear
weapons on human populations are described. The section ends with a description of how theestimates of each impact were combined to yield a total estimate of likely deaths resulting fromeach of the use cases, the results of which are presented in Section 6.

5.2 Evaluation of thermal fluence impacts
The impact of thermal fluence from each nuclear detonation on victims in the blast area wasevaluated in two steps: calculating the size of fluence “contours” relative to ground zero andestimating the populations within each contour.
The distances from ground zero of thermal fluence thresholds were calculated at 20, 15, 10, 5,
and 3 cal/cm2 using the declassified U.S. Defense Nuclear Agency (now the Defense Special
Weapons Agency) “Weapon Effects Calculator” software.63 This tool, released in 1984, waswritten to run under MS DOS, predating Windows. As a result, it requires an emulator such as“DOSBox” to run on a Windows operating system. A screenshot of the “Weapon Effects
Calculator” opening screen is provided in Figure 5-1.

63

This and other similar software tools are available from Nuclearweaponsarchive.org (undated), “Repository of
Nuclear Effects Computer Simulations and Models,” at https://nuclearweaponarchive.org/Library/Nukesims.html

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

40

Figure 5-1: Opening Screen of Defense Nuclear Agency “Weapon Effects” Program.
The weapon yield, height of burst, visibility (in km), and thermal fluence values were enteredinto the Weapon Effects tool to back-calculate the corresponding “ranges” (distances fromground zero) for each detonation. Thermal fluence from nuclear detonations is attenuated when
visibility is limited by humidity or particles in the air. A visibility of 10 km (10,000 meters)
representing less-than-ideal visibility (which would be closer to 50 km) was assumed whencalculating the range of each thermal fluence contour. Tests in selected detonations found thatthe difference in range between 10 km and 50 km visibility was relatively small—a few percent
to about 20 percent lower for 10 km visibility than for 50 km. Lower visibility of 10 km wasselected for all use cases, resulting in a slight underestimate of each thermal fluence range. The
results of each “backward calculation” were plotted as circular thermal fluence contours on a
Google Earth-based map projection using the open source “QGIS” GIS software.64 Figure 5-2
shows an example of the projected thermal fluence contours on a satellite image of the target
area.

64

QGIS software is available from QGIS (2023), “QGIS: A Free and Open Source Geographic Information System,” athttps://www.qgis.org/en/site/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

41

Figure 5-2: Example of Plot of Thermal Fluence Contours in QGIS: Use Case 2, First Use
Detonation 3 (DPRK).
The population within each thermal fluence zone was counted in QGIS by overlaying the contour
rings with the LandScan 2021 (landscan global-2021) and GPW(gpw_v4_population_count_rev11_2020_30_sec) population databases, each of which uses a
global resolution of 30 arc-seconds.65 The population estimates obtained using each databasevaried slightly from one detonation to another, up to around a factor of two. However, both
population databases produced results consistently on the same order of magnitude. Final results
were calculated using the LandScan 2021 database.

5.3 Evaluation of firestorm impacts
Of the two unspeakably horrific uses of nuclear weapons against the territory of a military
adversary, only the nuclear bomb dropped on Hiroshima by the United States in 1945 resulted in
the large-scale occurrence of a what is technically called a firestorm. Although much has beenlearned from that one example, despite many decades of research by nuclear weapons experts,
the factors that predict whether a nuclear detonation will result in a firestorm are not thoroughly
understood. Urban firestorms caused by the intensive use of thousands of conventional weapons

65

LandScan data downloaded from Oak Ridge National Laboratory (ORNL, probably 2022), “LandScan Global,”
https://landscan.ornl.gov/. GPW data downloaded from Socioeconomic Data and Applications Center (SEDAC,
probably 2021), “Gridded Population of the World (GPW), v4”, available fromhttps://sedac.ciesin.columbia.edu/data/collection/gpw-v4/sets/browse

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

42

in World War II have been studied as analogs to glean information on potential nuclear weaponignited firestorms, but they are an imperfect model.
What is clearly understood about nuclear weapons and firestorms includes the following:•

Above a certain level of thermal fluence from a nuclear weapon, many fires, andpotentially mass fires, will almost certainly ignite almost immediately and concurrently inthe area affected by a nuclear weapon, if the fuel exists to be burned. Whether those fires
will coalesce into a firestorm depends on a number of factors related to the location andtiming of the nuclear detonation, some of them not necessarily knowable in advance of an
attack.

•In an urban environment, multiple fires ignited concurrently will grow into larger fires
within 15 to 30 minutes.66 These large fires will generate large volumes of rising air overthe entire area. Rising air will in turn pull cooler air and more oxygen into the fire in its
wake, further increasing the intensity of the fire.

•

The radius of the firestorm will be self-limited by the potentially gale-force winds thatwill rush towards the fire from all sides.

•

Once started, a firestorm will result in the destruction of everything within its perimeter,
and, barring a small handful of miracles,67 the death of everyone within the firestorm
radius.

Considering these sobering characteristics, the potential impacts of firestorms resulting from
nuclear detonations were estimated by attempting to discern whether a firestorm will occur, therange out to which it will spread, and how many victims will perish in the blaze.
The general consensus on the minimum conditions necessary to support a firestorm is discussed
in the seminal 1977 work compiled by Glasstone and Dolan, which reads as follows:68“….Nevertheless, based on World War II experience with mass fires resulting from air raids
on Germany and Japan, the minimum requirements for a fire storm to develop are consideredsome authorities to be the following: (1) at least 8 pounds of combustibles per square foot offire area, (2) at least half of the structures in the area on fire simultaneously, (3) a wind ofless than 8 miles per hour at the time, and (4) a minimum burning area of about half a square
mile. High-rise buildings do not lend themselves to formation of firestorms because of thevertical dispersion of the combustible material and the baffle effects of the structures.”As definitive as the above sounds, it should be noted that the two sentences in Glasstone andDolan immediately preceding the passage above acknowledge the considerable uncertainties:“…Apart from a description of the observed phenomena, there is as yet no generally
accepted definition of a firestorm. Furthermore, the conditions, e.g., weather, ignition-point
density, fuel density, etc., under which a firestorm may be expected are not known.”
66

See, for example, United States Government Printing Office (1946), United States Strategic Bombing Survey: The
Effects of Atomic Bombs on Hiroshima and Nagasaki, dated June 30, 1946, and available ashttps://docs.rwu.edu/cgi/viewcontent.cgi?article=1000&context=rwu_ebooks
67
Some survivors of the firestorm following the bombing of Hiroshima, for example, survived in part by taking
refuge in l the rivers that flow through the city; Atomicarchive.com, “Eyewitness Account of Hiroshima By Father
John A. Siemes,” available as https://www.atomicarchive.com/resources/documents/hiroshimanagasaki/hiroshima-siemes.html
68
Glasstone and Dolan (1977), ibid, pages 299 and 300.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

43

Of the four conditions for firestorms described by Glasstone and Dolan, number (2) is easily
satisfied for all of the detonations in our five use cases, as all include yields that are above thethreshold where the radius of thermal fluence sufficient to ignite materials will produce a burning
area of over a half a square mile (about 1.3 km2) in extent. Similarly, by definition, the thermal
fluence values above the threshold will ignite virtually all exposed burnable materials within thatradius at once, satisfying Glasstone and Dolan’s condition (4). Whether or not an ambient windof 8 miles per hour (3.6 meters/second) is present (condition (3) will depend on the weather atthe detonation site at the time, which can be estimated based on past weather patterns, but does
not affect the potential for a firestorm to occur.
This account leaves condition (1), a fuel loading of 8 pounds of combustibles per square foot(about 39 kilograms per square meter), for further consideration. This threshold is a relatively
high bar for the development of a firestorm. By comparison, a 1991 study of fuel loads in cities
in the United States found that although residential and commercial buildings themselves had
fuel loads at or above this level (123 to 150 kg/m2 for residential buildings, and 39 to 273 kg/m2
for non-residential), the average fuel load over an “average US urban area” ranged from 14 to 21
kg/m2.69 An average urban area would likely include relatively open space at its periphery,
reducing the overall average, but even considering a reasonably dense suburb with houses
covering one-third of their lot areas, plus streets and sidewalks, fuel loadings might well notreach 39 kg/m2. Asian cities, which tend to be more dense on average than in the United States,
might raise the potential for fuel loadings to be higher, but many Asian cities make more use of
concrete and brick construction than is typical in the United States. Shifting to consideration ofrural detonations, a minimum fuel loading of 39 kg/m2 would all but eliminate the potential offirestorms in forests, as even the most dense forests barely reach that level of fuel loading.70
Although the Glasstone and Dolan conditions for firestorm formation are frequently quoted inother literature on nuclear weapon effects, the original source of the information is unclear. The
source may well have been anecdotal. There is a large body of literature, however, on forest
fires, that include descriptions of firestorm-like conditions—cyclonic winds and radial airflow ininstances where fires converge in clusters.71 These studies suggest that areas such as forests
where fuel loadings are much lower than the 39 kg/m2 indicated by Glasstone and Dolan, might
equally be subject to firestorms, although it is not definitely known what the minimum
conditions for a nuclear-caused firestorm should be. The fact that many large forest fires havebeen seen to create, in effect, their own weather through rising hot air masses above the flames,
69

B. Bush, G. Anno, R. McCoy, R. Gaj, and R. D. Small (1991), “Fuel loads in U.S. cities,” Fire Technology, 1991 Feb;
27(1):5-32, abstract available at https://pubmed.ncbi.nlm.nih.gov/10109450/
70
See, for example, Raphaël Proulx, Guillaume Rheault, Laurianne Bonin, Irene Torrecilla Roca, Charles A. Martin,
Louis Desrochers, and Ian Seiferling (2015), “How much biomass do plant communities pack per unit volume?”
PeerJ 2015, 3: e849, published online 2015 Mar 19
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4369330/
71
See, for example, Jason Sharples, James Hilton, Andrew Sullivan, and Rachel Badlan (2020), Fire Coalescence andMass Spotfire Dynamics: Experimentation, Modelling and Simulation: Annual project report 2019-2020, dated
4/11/2020, REPORT NO. 625.2020m available ashttps://www.bnhcrc.com.au/sites/default/files/managed/downloads/nb13-sharples-ar-2019-2020_rt_0.pdf; themuch older Clive M. Countryman (1964), Mass Fires and Fire Behavior, U.S. Forest Service Research Paper PSW-19,
available as https://www.fs.usda.gov/psw/publications/documents/psw_rp019/psw_rp019.pdf; and Mark A.
Finney and Sara S. McAllister (2011), “A Review of Fire Interactions and Mass Fires,” Journal of Combustion,
Volume 2011, Article ID 548328,14 pages, available ashttps://www.fs.usda.gov/rm/pubs_other/rmrs_2011_finney_m003.pdf

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

44

as a nuclear-caused firestorm would, suggests that the threshold for firestorms fuel loading could
be significantly lower than the 8 lb/ft2 (39 kg/m2) value.
Navigating these uncertain criteria for firestorms, for the purposes of our analysis the following
approach was used to estimate the number of deaths caused by firestorms for the five use cases
presented in Section 6 of this Report:•

The radius of the potential firestorm zone for each detonation was assumed to occur
within a thermal fluence threshold of greater than 15 cal/cm2 for detonations with yields
50 kT and over, and greater than 10 cal/cm2 for detonations of smaller yield.72 Figure 5-3
shows an example of the estimated extent of a firestorm for one of the detonations in
Evaluated Use Case 2.

•

Weather conditions could affect firestorm formation, for example, when ambient winds
are strong enough to prevent a firestorm from forming, or when snow on the ground or
cloud cover multiplies thermal fluence, increasing the range from ground zero to which afirestorm perimeter could extend. We did not, however, attempt to make adjustments forpotential weather conditions at the time of detonation.

•

Satellite imagery of the target area for each detonation was examined to assess whether it
seems possible that enough fuel is present to allow a firestorm to form. For example,
detonations at desert locations, at other rural locations with highly varied topography
and/or limited numbers of dwellings and biomass, at non-rural locations in which asubstantial portion of the area of potential firestorm zone was covered with concrete(such as a large area of tarmac), and explosions wholly or mostly over water are assumed
to result in no firestorm development. In general, nuclear detonation targets where
firestorm development was assumed to be possible included built-up areas in at least
portions of the targets, a large housing zone at least as dense as in a typical suburb, and/or
significant fossil fuel stores, such as oil tanks.

•

If a firestorm does form, effectively all of the population inside the firestorm zone will
perish.

•The results presented in Section 6 acknowledge the uncertainty of firestorm formation by
separating estimates of additional deaths due to firestorms—that is, deaths beyond thosecaused by other effects of each nuclear detonation—from estimates of deaths due to othernuclear weapons impacts.

Due in part to the large uncertainties associated with predicting firestorm occurrence and extent,
nuclear weapon targeteers do not traditionally consider firestorm effects when planning nuclear
attack strategies. The existence of uncertainties, however, does not mean that firestorm impacts
are insignificant or negligible. On the contrary, we believe that simply ignoring firestorm
impacts in an analysis of humanitarian consequences of nuclear conflict is irresponsible. In thisanalysis, an attempt was thus made to include an estimate of firestorm impacts in addition to the
traditionally considered direct impacts.

72

These thermal fluence limits for firestorms caused by weapons yields of different sizes were suggested by
Theodore Postol, personal communication, 12-12-2022. The limit used for smaller detonations, 10 cal/cm2, isroughly consistent with experience of areas where large numbers of fires were set in the bombings of both
Hiroshima and Nagasaki.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

45

Figure 5-3: Example Image of Potential Firestorm Zone (orange shaded area) in QGIS:Use Case 2, Response Detonation 2 (Yokohama, Japan).

5.4 Evaluation of blast overpressure impacts
The impacts of blast overpressure on the populations located near ground zero was, as withthermal fluence, evaluated in two steps: calculating the distances from ground zero affected byvarious overpressure thresholds, then counting the population within each contour.
The distances from ground zero of peak overpressure thresholds (that is, the highest
overpressures experienced at each distance) were calculated at 10, 8, 5, 2 and 0.5 psi (in SI units,
about 69, 55, 34, 14, and 3.5 kilopascals (kPa), respectively) using the declassified U.S. Defense
Nuclear Agency (now the Defense Special Weapons Agency) “Weapons Effects Calculator”
software.
For each detonation, the weapon yield, height of burst, and overpressure thresholds were input
into the Weapon Effects Calculator and a backward calculation was run to output the distancefrom ground zero corresponding to each overpressure value. As with thermal fluence, theresulting circular contours of overpressure were plotted on a Google Earth-based map projection
using the open source QGIS software.73 Figure 5-4 shows an example of peak overpressure73

QGIS software is available from QGIS (2023), “QGIS: A Free and Open-Source Geographic Information System,”at https://www.qgis.org/en/site/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

46

contours mapped onto a satellite image of the target area. The largest contour (shown in blue)
encompasses the area in which the blast wave will reach a peak overpressure of 0.5 psi or
higher—enough to break the glass in windows and cause other minor damage.

Figure 5-4: Example of Peak Blast Overpressure Contours Mapped in QGIS: Use Case 2,
Additional Detonation 10 (South China).

5.5 Evaluation of prompt radiation exposure
The short and long-term health impacts on a population from prompt radiation doses, acquired
instantaneously from the fission explosion itself, were evaluated in two steps: calculating the
distances from ground zero corresponding to various radiation dose levels, then estimating the
population within each zone.
The distances from ground zero of prompt radiation thresholds were calculated at 200, 100, 50,
25, and 10 rem (2, 1, 0.5, 0.25, and 0.1 Sv) using the declassified U.S. Defense Nuclear Agency“Weapons Effects Calculator” software.
For each detonation, the weapon yield, height of burst, weapon type (selected from 15 available
options), and relative air density, and radiation dose thresholds were input into the software.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

47

Since some kinds of radiation are attenuated in air, thus the exposure rate also depends on the air
density. The relative air density was calculated using the formula
𝐴𝑙𝑡𝑖𝑡𝑢𝑑𝑒 1.04
)
−(
13000
Air Density = ewhere the altitude of each target was estimated using Google Earth Pro. Then, a backward
calculation was run to output the distance from ground zero corresponding to each radiation dosethreshold. The resulting circular contours of prompt radiation exposure were plotted on Google
Earth-based map projections using the open source QGIS software.74 Figure 5-5 shows anexample of radiation exposure contours mapped onto a satellite image of the target area.75

Figure 5-5: Example of Prompt Radiation Exposure Contours Mapped in QGIS: Use Case2, Response Detonation 1 (Camp Humphries, ROK).

74

QGIS software is available from QGIS (2023), “QGIS: A Free and Open-Source Geographic Information System,”at https://www.qgis.org/en/site/
75
Although the contours appear to be ellipses in this and later images, they are actually circular. The ellipse shapeseen is an artifact of the distortion of the map itself at higher latitudes, the result of projecting the threedimensional globe onto a two-dimensional image.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

48

5.6 Evaluation of fallout radiation exposure
Simulations of nuclear fallout dispersion from the moment of detonation to four days after wereconducted using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT)
Model,76 and the resulting accumulated biological radiation dose to the exposed population was
estimated. HYSPLIT results were postprocessed using Python, then contoured and analyzed
according to the levels shown in Figure 5-6 using the free QGIS software described above. The
population affected by each radiation dose level was estimated by overlaying the dose contours
with the LandScanTM Global 202177 population dataset.

Figure 5-6: Biological Radiation Dose Levels (rem) Used to Visualize and Analyze HYSPLIT
Simulation Results.
HYSPLIT is a general-purpose atmospheric transport model distributed by the U.S. National
Oceanic and Atmospheric Administration’s (NOAA) Air Resources Laboratory. One major
limitation of HYSPLIT is its assumption of a stabilized cloud source. In reality, the dispersion ofmaterial following a nuclear weapon detonation is not stabilized, but constitutes hot, high-speed
winds rising explosively in complex patterns. Current nuclear fallout codes that have been
specifically developed by the US government have been found to be more accurate predictors ofparticle dispersion.78 However, codes such as these that simulate more complex source terms
have become government-classified and are no longer accessible to the public. Therefore,
although there is a learning curve to using it, HYSPLIT has been selected for this project because
it is a free and publicly accessible tool. Affiliation with a research or corporate organization may
facilitate the acquisition of some files and resources for prospective users of HYSPLIT.
HYSPLIT can be used to simulate the forward or backward trajectories of pollutant dispersion
based on a known input source or downwind measurement (in the case of an unknown source).
76

Stein, A.F., Draxler, R.R, Rolph, G.D., Stunder, B.J.B., Cohen, M.D., and Ngan, F., (2015). “NOAA’s HYSPLIT
atmospheric transport and dispersion modeling system,” Bull. Amer. Meteor. Soc., 96, 2059-2077,
http://dx.doi.org/10.1175/BAMSD-14-00110.1
77
LandScan 2021 downloaded from ORNL (2022), ibid.
78
Jerrad P. Auxier, John D. Auxier, Howard L. Hall (2017), Review of current nuclear fallout codes, Journal ofEnvironmental Radioactivity, Volume 171, Pages 246-252, ISSN 0265-931X,
https://doi.org/10.1016/j.jenvrad.2017.02.010

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

49

The model includes a built-in function that converts ground or air concentrations to biologicalradiation dose, utilizing an input file that lists Becquerel (Bq) to rem (or Sv) conversion factors
for a list of nuclear isotopes. The radiation dose conversion factor input file used in this analysis
contains around 200 isotopes and is now provided by the October 2022 HYSPLIT tutorial onradionuclide applications.79
HYSPLIT uses real-world historical or forecast meteorological data in its particle dispersion
simulation. Meteorological data were downloaded directly from the NOAA Real-time
Environmental Applications and Display sYstems (READY) website,80 the same website thatprovides HYSPLIT for public use. The Global Forecast System weather data,81 which includes
wind speed, direction, and precipitation information, was used with a grid resolution of 0.25degree spatial intervals.
Several key assumptions were made to model the cloud of radioactive material produced by anuclear detonation, known as the HYSPLIT “source term.” In reality, the nuclear cloud attains its
maximum height after about 10 minutes, continuing to grow laterally to a mushroom shape as it
is dispersed by atmospheric winds.82 In the HYSPLIT simulation, however, the source term (thecloud of radioactive materials) was modeled as a line source at its stabilized cloud height. A
discussion on HYSPLIT fallout simulation assuming a stabilized nuclear cloud can be found in
Rolph et al.83 It is also necessary to define a particle-size distribution and altitude-dependentradioactivity distribution. These distributions were selected from the work done by Philippe etal.84
The simulation parameters used to run nuclear fallout simulations in this project are summarizedin Table 5-1. Italicized and underlined values vary based on the detonation, and values fromfirst-use detonations #2 and #3 from Use Case 2 are provided as an example. Figure 5-7 shows
an example projection of HYSPLIT fallout contour results for a detonation in evaluated Use
Case 2.

79

Hysplit.com (undated); “Simulation of the Smoky Nuclear Test,” available ashttps://hysplit.com/html/smoky_test.html
80
NOAA Air Resources Laboratory (undated), “READY (Real-time Environmental Applications and Display sYstem),”available as https://www.ready.noaa.gov/index.php
81
NOAA (undated), “Global Forecast System (GFS),” available ashttps://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs.php
82
Glasstone and Dolan (1977), ibid, section 2.15.
83
G.D Rolph, F. Ngan, and R.R. Draxler (2014), “Modeling the Fallout from Stabilized Nuclear Clouds using the
HYSPLIT Atmospheric Dispersion Model”, Journal of Environmental Radioactivity, Volume 136, October 2014, Pages
41-55 available as https://www.sciencedirect.com/science/article/pii/S0265931X14001453
84
Sébastien Philippe, Sonya Schoenberger, and Nabil Ahmed (2022), “Radiation Exposures and Compensation ofVictims of French Atmospheric Nuclear Tests in Polynesia,” Science & Global Security, vol. 30, Issue 2 (2022), 1-33,
available as https://doi.org/10.48550/arXiv.2103.06128

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

50

Table 5-1: HYSPLIT Simulation Parameters (italicized, underlined values are variable
based on detonation)
Simulation Parameter

Surface-burst

Airburst

Meteorology Data

Global Forecast System(0.25 deg)““

Simulation Run Time

96 hours

““

8 kT

““

Detonation Date / Time

2021 09 30 17 10 UTC

2021 09 30 18 00 UTC

Ground Zero Location

40.83, 128.56

38.96, 125.61

Height of Burst (HOB)

0m

450 m

# Cloud Layer Heights85

4Source Release Duration
Activity Distribution86(cap/skirt/stem)# Particle Sizes

6 min*Surface-burst heights
raised by HOB““

0.775 / 0.15 / 0.075

0.9712 / 0.0283 / 0.0005

100
X ~ LogN (d=0.407 µm,
σ=4)
2.5

““
X ~ LogN (d=0.150 µm,
σ=2)3Particle Density

2.5 g/cm3

4.8 g/cm3

Output Concentration
Heights

0, 500 m““

Output Grid Resolution

0.05 deg““

Weapon Yield

Particle Size Distribution /Moment of Distribution87

85

Specific height of each cloud layer was estimated based on Glasstone and Dolan Figure 9.96, “Altitudes of thestabilized cloud top and bottom as a function of total energy yield for surface or low air bursts,” p. 431, andPhilippe et al. at https://doi.org/10.48550/arXiv.2103.06128
86
Philippe et al., “Radiation Exposures and Compensation of Victims of French Atmospheric Nuclear Tests in
Polynesia,” p. 24, https://doi.org/10.48550/arXiv.2103.06128
87
Defense Technical Information Center (1979), DELFIC: Department of Defense Fallout Prediction System. Volume
I – Fundamentals, Final Report 16, January -31 December 1979, available fromhttps://apps.dtic.mil/sti/citations/ADA088367

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

51

Figure 5-7: Example Fallout Radiation Exposure Map as Simulated using HYSPLIT and
Projected in QGIS: Use Case 2, Response Detonation 1 (Camp Humphries, ROK).
HYSPLIT simulation results provide an indicative example of the direction and distance fallout
from a nuclear detonation might travel and possible ground and air concentrations at the locationof deposition. These results highly depend on weather conditions and can vary widely. Selecting
the time of a nuclear attack that is just days or hours different may result in a decidedly different
pattern of deposition, and different levels of radiation exposure to the populace. To gain anumerical understanding of the likelihood of fallout deposition patterns, many more simulations
would need to be run. Thus, the HYSPLIT simulations in this report provide only an indicative
example of what might happen under one real-world weather pattern.

5.7 Estimation of radiation-induced cancers from exposure to prompt and fallout
radiation dose
Estimates of radiation-induced cancer deaths, defined as the number of additional cancer deathsin the lifetime of a population due to widespread exposure to nuclear radiation, were calculated
based on the estimated exposure to prompt and fallout radiation and a statistical dose-response
factor. Starting with the radiation dose contours and corresponding population estimates counted
using the method described above, the number of long-term radiation-induced cancer deaths wasestimated using the following method:
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 252

1. Counting the population within three exposure zones: 10–50 rem, 50–100 rem, and 100–
200 rem (10 rem = 100 mSv). Both prompt and fallout radiation zones were considered
if they were not already subsumed by a more deadly health effect.
2. Calculating an upper and lower estimate of the total dose received by the population inperson-Sv. The upper estimate assumed dose exposures of 50, 100, and 200 rem in eachzone, and the lower estimate assumed dose exposures of 10, 50, and 100 rem in eachzone.
3. Multiplying the person-Sv values by 0.055—the estimated additional number of cancer
deaths in a population per Sv —to estimate the number of radiation-induced cancer
deaths in each exposure zone.88
4. Populations in radiation exposure zones below 10 rem were not included in thecalculation of additional cancer deaths based on the assumption that “quantification ofcancer risk at doses of less than 0.1 Gy [10 rem of gamma radiation] remains
problematic.”89 We also do not estimate cancer deaths in populations exposed to over
200 rem (2 Sv) of radiation, as any acute dose above 200 rem is likely to result in shortterm health complications leading to death before cancer develops.
5. Summing the radiation-induced cancer deaths estimated in step 3 over all prompt andfallout radiation exposure zones to yield the total number of estimated cancer deaths
resulting from each nuclear detonation.90

5.8 Estimation of the aggregate impact of the effects of nuclear detonations
The detonation of a nuclear weapon would cause mayhem, destruction, injury, sickness, anddeath to those in the afflicted area. The distribution of physical, socioeconomical, financial,
cultural, and political outcomes is uncertain and difficult to predict. Of the various metrics used
to understand the consequences of a nuclear attack, the number of deaths is the most concerning
to society and most physically understandable to policymakers. Therefore, an attempt has been
made to develop a methodology to estimate the number of deaths resulting from the nuclear
attacks in Use Cases 1 through 5.91 Future work should also include more thorough discussionsof the less quantitative but undeniably devastating effects of nuclear detonations on society.
Before describing our methods for combining each separate impact into one estimate of the total
deaths resulting from each nuclear use, two points must be emphasized.

88

0.055 (or 5.5 percent) additional cancer deaths per Sv of radiation exposure taken from Fred A Mettler (2012),“Medical effects and risks of exposure to ionizing radiation,” Journal of Radiological Protection. 32 (2012) N9–N13,
available from https://pubmed.ncbi.nlm.nih.gov/22395124/
89Fred A Mettler (2012), ibid.
90
The protocol for estimating excess cancer deaths described here was prepared with much-appreciatedassistance and input From Professor Noboru Takamura of Nagasaki University (personal communications, 1-272023).
91
Using deaths not only does not capture all of the physical effects on the populations affected by nuclear
detonations, but also does not capture the psychological and culturally annihilative effects of nuclear attack on
survivors at Hiroshima and Nagasaki, effects described using the term “psychic numbing” by Robert Jay Lifton, in
Death in Life: Survivors of Hiroshima, Random House, 1968.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

53

First, for each of the individual impacts considered, the fraction of the population killed in theaffected area by any level of prompt or fallout radiation exposure, by thermal fluence, byoverpressure, or, in future decades, by cancer, is subject to many uncertainties. These
uncertainties include (but are certainly not limited to):•

Weather, which can affect the impacts of a nuclear attack in many ways, from attenuating
thermal fluence on foggy or hazy days to amplifying it when clouds or snow is present, topreventing the formation of firestorms when it is windy, but potentially fanning theflames of fires set by thermal fluence and from fuel sources within blast-affected areas.
Weather patterns also affect where fallout is deposited via rain or wind and can impede
efforts to rescue and provide medical care for survivors. The weather on the day of thenuclear attack may make populations more or less vulnerable by affecting where they areat the time of the nuclear explosion, and thus how exposed or protected they are.

•

The degree to which a target is destroyed by overpressure and thermal fluence at any
given distance from ground zero depends on how resilient the infrastructure is to thoseforces, which in turn affects the survivability of those protected (or not) by resilient
infrastructure.

•

Where fires will ignite, which affects both mortality and the ability of blast victims toescape to safer locations, and uncertainty as to whether a large-scale firestorm willdevelop and where it will spread.

•The organization or lack of emergency services in the immediate aftermath of adetonation. The availability and timeliness of medical care will in part determine whether
victims of the immediate attack will survive their wounds. The ability of emergency
responders to access the affected area from surrounding towns, provinces, and evencountries may be impeded by ongoing conflicts.

•

The affected population’s ability to use intended or impromptu shelters to shieldthemselves from overpressure, thermal fluence, and radiation exposure, which will also
have a significant impact on survival chance.

•

The fraction of survivors who will succumb to their injuries or secondary health impacts
such as infections in the days, weeks, or months following the initial attack.

Second, since the impacts of nuclear detonations have overlapping areas of effect, the numbersof deaths resulting from each individual impact are not additive. Specifically, as prompt radiation
exposure, thermal fluence, and overpressure are concentric with ground zero of the detonation,
substantially overlapping, the impacts of those three effects cannot be simply summed to yield
total deaths from all three. Instead, each of the three impacts contributes to reducing victims’survivability. If a firestorm occurs, there will be essentially no survivors within the radius of thefirestorm. If the firestorm radius exceeds the lethal radius of other impacts, as in many high-yieldweapon detonations, the deaths from firestorms will subsume most or all of the deaths from otherimpacts. Radiation doses acquired from fallout primarily do not overlap with other impacts,
mostly occurring outside the range of prompt radiation, thermal fluence, and overpressure.
Therefore, except in instances where the zones of highest fallout overlap the lethal zones of otherimpacts, fallout deaths are additive to prompt deaths. Radiation-induced cancer deaths, occurring
years or decades after the detonation, are also additive to total short-term deaths from othereffects.
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

54

Considering these uncertainties and overlapping impacts, the number of “likely deaths” resulting
from nuclear detonations in each Use Case was estimated under the following assumptions:
1. A lethal prompt and fallout radiation dose threshold of 200 rem (2 Sv) was assumed.
The survivability of victims exposed to 200 rem of radiation or higher greatly depends on
prompt and ongoing access to quality medical care, and the availability of medical carefollowing a nuclear attack is difficult to predict.
2. The lethal threshold of thermal fluence was assumed to be 20 cal/cm2. For exposed
individuals, this level of thermal fluence will produce third degree burns even throughmany types of clothing, and will cause most combustible materials to ignite, meaning thateven those sheltered from exposure to the initial pulse of heat will likely be trapped byfire.
3. The 100% lethal peak blast overpressure threshold was assumed to be 5 psi, which is
sufficient to destroy wood-framed buildings and severely damage most other buildings.
Individuals not trapped in buildings as they collapse may be injured or killed by flying
debris and subject to fires that ignite when electrical lines, gas piping, or vehicles aredamaged. In addition to the severe damage zone (5 psi), a death rate of 14% prompt and18% short-term was considered in the moderate damage zone (2 psi) and 8% / 14% in thelight damage zone (0.5 psi).92 It was assumed that all victims suffering serious injuries
and requiring hospitalization would succumb to their wounds within a year of the attack
due to a combination of physical injuries, burns, and radiation dose exposure, lack ofsurvival morale, and insufficient medical care.
4. For targets where a firestorm is considered possible, it was assumed that 100% of the
population within the firestorm zone, estimated as in Section 5.3, would perish.
5. Total estimated likely deaths were calculated in several steps, as summarized in Figure5-8. First, prompt and short-term deaths due to thermal fluence, overpressure, and prompt
radiation levels were calculated based on the procedures shown in Figure 5-9. Then, forlocations where a firestorm is likely, the 100% lethality firestorm zone was inserted, andpopulation counts in other zones adjusted accordingly.
6. Next, if the range of 10 – 200 rem prompt radiation exposure was greater than any 100%lethality zone, low and high estimates of the number of long-term radiation-induced
cancer deaths were calculated without adjusting for the impact zone overlap withmoderate and light damage zones. Finally, short-term deaths due to high doses of fallout
radiation and long-term radiation-induced cancer deaths occurring outside of the 100%lethality zones were estimated using the methods described in Section 5.7.
7. For each use case, we summed the total estimated prompt and short-term deaths for eachdetonation, calculated as above, and separately listed the number of estimated deaths
added due to the occurrence of firestorms. The estimated number of short-term deaths
resulting from fallout radiation and cancer deaths are also reported separately.

92

Glasstone and Dolan (1977) ibid, Table 12.21, “Casualties in Reinforced-Concrete Buildings in Japan Related to
Structural Damage.”

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

55

Figure 5-8: Overall Calculation Flow to Estimate the Fatalities caused by Nuclear
Detonations.

Figure 5-9: Nuclear Detonation Fatality Estimation Method based on Blast Overpressure,
Prompt Radiation, and Thermal Fluence.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 256

6

Estimated Fatalities Due to Nuclear Detonation Impacts

This section presents the simulation results of evaluated Use Cases 1 through 5. For each usecase, the number of prompt, short-term, and cancer fatalities resulting from nuclear detonation
impacts was estimated. Tables of key inputs and summarized narrative descriptions of each use
case are provided, followed by maps and tables depicting the quantitative results of thesimulations. Detailed narratives illustrating the evolution of each use case are included in Annex
2. Finally, this section provides overviews and discusses implications of the estimated impacts ofeach use case. More detailed results, including analytical descriptions of individual detonations,are provided in Annex 3.

6.1 Use Case 1: “We’re Still Here”
In this use case, the DPRK, facing internal and external economic pressures, undertakes what canbe thought of as a “demonstration” nuclear attack on a small ROK coastal community for themain purpose of driving the United States, the ROK, and the international community to thebargaining table. To retain consistency with a policy of using nuclear weapons only in defense, it
is possible that the DPRK justifies the attack by contending that the ROK community was host to
an ROK Navy or Coast Guard contingent that has transgressed into DPRK territory andthreatened DPRK citizens. Spurred by the ROK, the United States responds using conventional
weapons to mount an attack on the DPRK’s artillery units near the DMZ and two low-yield
nuclear weapons on buried targets thought to conceal ICBMs and other nuclear assets capable ofthreatening the United States and its allies. Further nuclear conflict is averted by intensive
diplomacy. Table 6-1 lists the key parameters used to model the detonations in this use case.

Table 6-1: Use Case 1 Nuclear Detonation Parameters93
Use Case
First User

“We’re Still Here” V1First Use Targets

Village on ROK East Coast#1
First Responder
First ResponseType of
Delivery
HOB (m) Yield (kT)WeaponSystem700
10 Fission
KN-23
United States
Nuclear missile bases in DPRK

#1
#2

DPRK

Location
38.503,128.430

Location
39.662,125.347
40.8266,
128.555

Type of
HOB (m) Yield (kT)Weapon2-stage H0
8 2-stage
bomb H
08
bomb

Date andTime of
Attack*2/14/2023,
14:00

Date and
DeliveryTime of
SystemAttack*
SBN W76- 2/16/2023,
03:00
SBN 2W76- 2/16/2023,
2
03:00

93

In this Table and similar tables for each use case presented in this section, “Date and Time of Attack” is given as
the local time at each target.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

57

Figure 6-1 summarizes the results of the Use Case 1 simulation. Even though the targets are
fairly remote, far from population centers, and the exchange of nuclear weapons is limited tothree detonations, it was estimated that approximately 5,500 people would be killed within days
or weeks of the attack, with another 5,600 victims within the following year. An estimated
16,000 to 36,000 could be victims of radiation-induced cancer death in the decades that follow,
due to fallout radiation exposure.
In this use case, the occurrence of firestorms is unlikely due to the remote location of eachdetonation. The first nuclear weapon is detonated offshore by the DPRK. Much of the affectedarea around ground zero is covered by ocean, where the occurrence of a firestorm is not possible.
The areas around the other two detonations are characterized by low to medium-density forestsand fields over rugged terrain, likely insufficient to fuel the development of a firestorm.
However, forest fires are probable.
Out of the 41,000 people living within the 0.5 psi overpressure zones of the detonations includedin this use case, roughly 11,000 or 27% are likely to die within the year following the attack. In
some cases, survivability is highly dependent on medical care and hospital capacity.
A note about the person icons in the figures that follow in this section:•

Atomic Bombings, 1945

1945 Attacks on Hiroshima andNagasaki by the United States*Short-term deaths:
City of Hiroshima reports 140,000 deaths by the end of 1945, athttps://www.city.hiroshima.lg.jp/soshiki/48/9400.html
City of Nagasaki reports 73,884 deaths by the end of 1945, at
http://city.nagasaki.ajisai-call.jp/faq/show/3705
140,000 + 73,884 = 213,884 in the two bombings.
**Long-term deaths: Combined leukemia and other cancers, “all doses,”from Masao Tomonaga (2019), “The Atomic Bombings of Hiroshima andNagasaki: A Summary of the Human Consequences, 1945–2018, andLessons for Homo sapiens to End the Nuclear Weapon Age,” Journal for
Peace and Nuclear Disarmament, Volume 2, Number 2, dated December
2, 2019, Table 2, p. 513, and available ashttps://www.tandfonline.com/doi/full/10.1080/25751654.2019.1681226

To help readers quickly grasp the magnitude of calamity represented by the nuclear explosions in
the illustrated use cases, we have added icons to images in this section showing, at a glance, themedian estimated deaths projected in the first year after the use of nuclear weapons (white icons),
and over the longer term from nuclear-induced cancers (grey icons). The purpose of these icons is
to give the reader an impressionistic sense; for more-specific figures, see the tables and text.
The figure shown above as an example illustrates estimated numbers of deaths from the Hiroshima
and Nagasaki bombings on August 6 and 9, 1945. The white icons represent 213,884 deaths within
one year (21⅓ icons, each representing 10,000 deaths) and the small grey sliver of the rightmost
icon (arrow) represents 853 long-term cancer deaths. These figures are very rough approximations,but should give a sense of how the deaths projected in various use cases discussed in this reportcompare with the scale of the Hiroshima and Nagasaki bombings.
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

58• Attack by DPRK on remote
ROK target

Use Case 1• Response Detonations by US
on DPRK nuclear targets• Further attacks prevented byintensive diplomacy,
restraint by other nuclear
powers* In this figure and those that follow, “Estimated Likely Deaths” denotes populations within impact zones where one or more
impacts will be lethal. These counts include “prompt” deaths that occur within days or weeks, and “short-term” deaths within
about one year from injuries sustained as a result of detonations, but do not include deaths from additional eventual cancers
caused by radiation (the latter are listed separately). Individual impacts may not add up to the exact Total shown due to rounding.

Figure 6-1: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting
from Use Case 1, All Detonations.
Figure 6-2 depicts the fallout resulting from detonations in evaluated Use Case 1. Winds carrying
the radioactive particles to the southeast of the two detonations in the DPRK cause significant
exposure to radiation in the affected populations. There is no fallout from the first detonation on
the east coast of the ROK due to the relatively low yield of 10 kT detonated at a relatively highheight-of-burst (HOB) of 700 meters. To limit the simulation time, the longitudinal range
simulated was limited. In reality, the fallout appears to spread even further into northern Japan
than depicted in Figure 6-2.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 259

Figureresolut

Figure 6-2: Nuclear Fallout Simulation Results for Use Case 1, Radiation Dose Units
in rem.
Even though short and long-term health impacts, including estimated cancer deaths, are limited
to the Korean Peninsula, the fallout simulation shows that if relatively low-yield weapons (8 kT)
are detonated at surface-level on the Korean Peninsula, significant levels of fallout may spread
across the East Sea and be detected as far away as northern Japan. People in some regions may
acquire a radiation dose exceeding 0.1 rem, the United States Nuclear Regulatory Commission(USNRC) Annual Radiation Dose Limit to the Public, within four days.
Although there will likely be no direct health impacts resulting from this low level of exposure,
Use Case 1 may have significant political impacts in Northeast Asia by dragging Japan, Russia,
and China into the conflict over concern about nuclear fallout levels. Residents of the ROK may
fear that nuclear fallout from American attacks has inadvertently spread into their country as
well, causing critics to lose faith in the benefits of the “nuclear umbrella” or even any alliancewith the United States. In addition, since the attacks by the United States resulted in cross-border
nuclear fallout but the attack by the DPRK did not, this could be seen as a political victory for
the DPRK, smearing the United States’ international reputation.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

60

Use Case 1 Implications: Even if relatively low-yield, nuclear weapons detonated on or near thesurface can result in international cross-border nuclear fallout, unintentionally dragging allies
and adversaries into the conflict, which can have severe political consequences, decrease trust inalliances, and spread fear in members of the public due to a lack of understanding of nuclear
fallout and the biological effects of radiation.

6.2 Use Case 2: “US Leadership Hubris”
In this use case, overconfidence—in both offensive nuclear weapons capabilities and missile
defense systems—on the part of the US president and the advisors that surround him or her, plus
political pressures at home, leads the president to order, and the United States to mount an attackon the DPRK’s nuclear and missile systems using conventional and nuclear weapons, with only
partial success. The United States is thus the party to use nuclear weapons in this use case.
The DPRK responds with a nuclear missile attack on a US base in the ROK, and DPRK Special
Forces attack mixed industrial targets in the Incheon (ROK) and Yokohama (Japan) areas withhand-carried nuclear devices.
The United States counters with additional nuclear attacks on DPRK nuclear and leadershiptargets, causing China to attack US bases in the region, followed by additional US and Chinese
attacks on key military installations in each country. In total, 18 nuclear weapons are detonatedin Use Case 2, the parameters for which are shown in Table 6-2.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

61

Table 6-2: Use Case 2 Nuclear Detonation Parameters“US Leadership Hubris”

Use Case
First User

United States

DPRK Nuclear Facilities

First Use Targets

#1
#2
#3
#4
#5
First Responder
First Response
Targets

Type of
Location
HOB (m) Yield (kT)Weapon39.662, 125.347
0
8 2-stage H bomb
40.8266,
128.555
0
8 2-stage H bomb
38.957, 125.611
450
8 2-stage H bomb
39.798, 125.755
450
8 2-stage H bomb
39.09, 125.91
450
8 2-stage H bomb
DPRK

#3
Additional
Detonations

#1
#2
#3
#4
#5
#6
#7
#8
#9
#10

Date and Time of
Attack*10/1/2026, 02:00

SBN W76-2
SBN W76-2
SBN W76-2
SBN W76-2

10/1/2026, 02:10
10/1/2026, 3:00
10/1/2026, 02:20
10/1/2026, 3:10

US Bases and ROK/Japan Infrastructure Targets

Location#1#2

Delivery
System
SBN W76-2

36.974, 127.002
35.409, 139.630
37.4463,
126.607

Yield (kT)Type ofWeaponDelivery
SystemDate and Time of
Attack*

0
0

20
10

FissionFission

10/1/2026, 06:00
10/7/2026, 02:00

0

10

Fission

KN-23 orOverlandship
Overland orship

HOB (m)10/7/2026, 02:30

US Attacks on Pyongyang, ICBM Exchange with China
Type of
Delivery
Location
HOB (m) Yield (kT)WeaponSystem39.113, 125.864-550 2-stage H bomb
B61-1239.124, 127.430-550 2-stage H bomb JL-1B61-12(SBL) or26.525, 128.046
1300
200 2-stage H bomb DF-21(MRBM)
JL-1 (SBL)or
26.356, 127.77
1300
200 2-stage H bomb DF-21(MRBM)
DF-5 (Aor B),
61.253, -149.77
1500
300 2-stage H bomb DF-5
DF-31(A(ICBM)
or B),
44.144, -103.08
1500
300 2-stage H bomb DF-5
DF-31(A(ICBM)
or B),
36.96, -76.3
1500
300 2-stage H bomb DF-31 (ICBM)
36.513, 103.606
1500
300 2-stage H bomb W87 (ICBM)
40.625, 115.117
1500
300 2-stage H bomb W87 (ICBM)
21.231, 110.445
1500
300 2-stage H bomb W87 (ICBM)

Date and Time of
Attack*10/14/2026, 03:00
10/14/2026, 03:10
10/15/2026, 04:00
10/15/2026, 04:10
10/14/2026, 11:00
10/14/2026, 14:30
10/14/2026, 15:40
10/16/2026, 03:00
10/16/2026, 03:10
10/16/2026, 03:20

Figure 6-3 through Figure 6-5 illustrate the results of the Use Case 2 simulation. Figure 6-3
shows the results after the first-use detonations, Figure 6-4 shows the cumulative results after the
response detonations, and Figure 6-5 shows the results following all attacks.
The first-use detonations by the United States are unlikely to result in firestorms. Although
individual fires will destroy forests and residential areas, the areas around ground zero in eachcase are mostly fields and sparse forest with few buildings. The overall density of this kind of
terrain is likely too low to fuel a firestorm. Special consideration, however, must be given to theattack on Yongbyon, a DPRK nuclear fuel cycle facility. Depending on the kind of materials
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

62

stored at the facility, fires occurring at the Yongbyon site may release additional radioactive
emissions. These emissions were not considered in this simulation but should be considered by
future work.
Most of the fatalities caused by the first-use attacks in Use Case 2 result from high levels ofprompt radiation in the case of low-yield surface-bursts, or by far-ranging blast overpressure
effects causing building damage and collapse in the case of airbursts.

Use Case 2• First-Use Detonations by the US
on DPRK Nuclear Arsenal andSupporting Infrastructure*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-3: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting
from Use Case 2, First Use Detonations.
Response detonations by the DPRK include industrial targets that are in or near population
centers, resulting in a drastic increase in the death toll of the conflict. Following the five first-use
detonations, 84,000 people are killed by prompt effects. After three response detonations, thetotal death toll of the use case reaches an estimated 400,000 within one year, more than fourtimes higher. Additionally, since the response detonations are detonated at surface-level, asignificant number of additional fatalities may result from exposure to high doses of nuclear
fallout radiation within hours to days following the attack. In the previous attack phase, up to
12,000 people are exposed to fatal levels of fallout radiation. Following the response detonations,
11,000 to 1 million people may acquire a fatal radiation dose from fallout. The long-term cancer
deaths in populations affected by the response detonations could also increase by an order ofmagnitude due to fallout, from an estimated 17,000 to 34,000 cancers to 400,000 to 670,000
cancers.
Firestorms will likely result from two of the detonations in this phase of the conflict, although
due to the far-ranging effects of prompt radiation associated with low-yield surface-bursts,
radiation effects have the most significant impact on the number of fatalities in these attacks.
Nevertheless, some of the areas around ground zero in these two detonations include dense
housing and infrastructure, large fuel tanks that could explode, and enough fuel debris fromoverpressure damage that a firestorm could ignite secondary fires even outside the firestorm
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

63

zone, eliminating any chance of survivability within the area of urban devastation and hindering
search-and-rescue efforts.

Use Case 2• First-Use Detonations by the US on
DPRK Nuclear Arsenal andSupporting Infrastructure• Response Detonations by the

DPRK on Targets in the ROK andJapan*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-4: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting
from Use Case 2, First Use and Response Detonations.
Ensuing attacks in the escalating conflict affect the DPRK, mainland China, Okinawa, and theUnited States. Whereas previous detonations were limited to lower-yield surface-bursts, the ten
additional nuclear weapons detonations in the escalating conflict are higher yield (200-300 kT)
airbursts and 50 kT sub-surface attacks on buried targets (simulated as surface bursts). In theaftermath of the sub-surface bursts, nuclear fallout radiation, blast overpressure, and prompt
radiation will have the most significant impact. In the case of high-yield airbursts, thermal
fluence and large firestorms increasingly dominate as the primary cause of death. This effect canbe observed in the results of the additional weapons detonations in Use Case 2. Even though thenumber of fatalities due to absorbed radiation doses do not increase by much in this phase of Use
Case 2, the number of fatalities quintuple from 400,000 to 2.1 million, due to the impact ofprompt thermal fluence and firestorms.
Firestorms will likely occur in five out of ten of the additional detonations in this use case, due tothe proximity of built-up areas to ground zero in those detonations. Extensive residential areas
nearby become fuel for raging firestorms when destroyed by the blast itself, and the possibility of
secondary fires spreading outside the firestorm zone is significant in several cases. Several of thedetonations occur on the coastline, where the firestorm zone will be limited by geography to theland areas affected by the detonations. This means that the estimate of firestorm impact in Use
Case 2 could be underestimated. If the targets were further inland, the firestorm impact could bemuch more significant.
Due to the outsized impact of high-yield thermal fluence and firestorms, not only does thenumber of estimated fatalities increase, but also the relative impact of the destruction becomes
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 264

greater. Following the first-use detonations in Use Case 2, around 29% of people in the 0.5 psi
overpressure zone are killed; following the response detonations, around 27% are killed. As theconflict continues to escalate, the percentage of people killed within the 0.5 psi zone increases to
33% in Use Case 2, demonstrating the significance of firestorms in increasing the lethality of
nuclear weapons. The impacts of firestorms can also be observed clearly in the results of Use
Case 4 and Use Case 5, as explained later in this section.

Use Case 2• First-Use, Response, and Additional
Detonations by Adversaries• Targets on the Korean Peninsula,
China, Japan (main island +Okinawa), and the United States (notshown)*Cumulative with First-Use and Response Detonations.
Individual impacts may not add up to the exact Total shown
due to rounding.

Figure 6-5: Targets, Estimated Likely Deaths, and Estimated Cancer Deaths Resulting
from Use Case 2, All Detonations.
Figure 6-6 shows the deposited fallout contamination resulting from Use Case 2, escalating
through each phase. When all nuclear detonation impacts are considered, up to approximately
one-half of all fatalities could be caused by nuclear fallout radiation, one-quarter due to acuteradiation effects and death within one year of the attack, and one-quarter due to radiationinduced cancer. The fraction of overall deaths due to fallout is highly uncertain and sensitive toprevailing weather patterns and the movement of affected populations within hours or days of theattack. The results of this simulated use case, however, show that nuclear fallout, althoughdifficult to predict, can greatly increase the death toll and economic and societal impacts of a
nuclear war.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

65

Use Case 2
Figure 6-6: Fallout Patterns Resulting from First-Use (upper left), First-Use and Response(upper right), and All (lower left) Detonations in Use Case 2.
By the end of the conflict, most of the areas surrounding the Sea of Japan/Korean East Sea,
southern China, and the Eastern Seaboard of the United States are covered by some level of
nuclear fallout. Radioactive contamination even spreads to regions politically and militarily
uninvolved in the conflict: southeast Asia and even the Caribbean Sea. As a result of nuclear war
in Northeast Asia, these regions are affected by significant levels of nuclear fallout. Furthermore,
southeast Asia and the Caribbean Sea are covered by nuclear-weapon-free treaties,94 unlike theother regions affected. This unintended consequence of nuclear war could have significant
regional and international political impacts.

94

See map of nuclear weapons free areas in Liviu Horovitz (2009), “African Nuclear-Weapon-Free Zone Enters into
Force”, Middlebury Institute of International Studies at Monterey, James Martin Center for Nonproliferation
Studies, dated August 12, 2009, and available as https://nonproliferation.org/african-nuclear-weapon-free-zoneenters-into-force/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

66

Use Case 2 Implications:•

When lower-yield weapons (20 kT or less) are detonated, which are more likely to be
surface-bursts, prompt radiation and high radiation from nuclear fallout can have a large
impact on the death toll. If the first-response detonation is a surface-burst, it may spur theadversary to also respond with one or more surface-bursts. If the responding adversary
increases the yield of their surface-burst, especially in a populated area, the death toll due
to both prompt and fallout radiation can drastically increase.

•

Use Case 1 and Use Case 2 both show that the attacks of responding adversaries tend to
be more lethal than first-use attacks as the conflict escalates. In both cases, the fallout of
the response detonations was more significant. In Use Case 2, population centers wereattacked in the response detonation phase as opposed to remote targets, and weapons oflarger and larger yield were increasingly detonated as the conflict escalated.

•

As the weapon yield increases, the impact of firestorms increases, whichdisproportionately decreases the survival chance of affected populations. Not only does
the fatality count increase, but also the percentage of deaths within the 0.5 psi zone,
which results in even greater economic and social consequences, and makes rebuilding
from the disaster even more painful and difficult for survivors.

•

High-yield airbursts can result in significant levels of regional fallout that crossinternational borders, even dragging regions covered by nuclear-weapons-free treaties
into the conflict, which can have significant political consequences and weakeninternational treaties.

6.3 Use Case #3: “Use by Terrorists” V1
An international or Japanese terrorist organization stages an attack meant to gain worldwide
attention by detonating a smuggled-in rudimentary nuclear warhead in the Shinbashi business
district of Tokyo.
Nuclear forensic analysis points to the DPRK as a source of nuclear material but is not strong
enough to be unequivocal. The DPRK denies any role in the attack or in providing weapons forthe attack. Responsibility for the attack is claimed by a stateless terrorist group.
Denial by the DPRK, the lack of clear evidence identifying DPRK proliferation as the source ofbomb materials, the DPRK offers to assist Japan in recovery, and its general pro-engagement
attitude convinces the United States not to use nuclear weapons against the DPRK, and further
escalation is avoided. The key simulation parameters of this single-detonation use case areshown in Table 6-3.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

67

Table 6-3: Use Case 3 Nuclear Detonation Parameters“Use by Terrorist” V1

Use Case
First User

Terrorist Attack

High Visibility Target in Tokyo

First Use Targets#1
First Responder
First Response
Targets
Additional
Detonations

Location
35.663,139.7587

Type of
Delivery
HOB (m) Yield (kT)Weapon Overland
Systemor
0
10 Fission
ship
US Response on DPRK (as possible proliferator)

Date andTime of
Attack*7/8/2025,
17:00[NONE--response considered, but not carried out]
[None]

Use Case 3 includes a single detonation of a weapon in central Tokyo. Figure 6-7 shows asatellite image of the detonation zone with rings indicating the areas within which there will be
exposure to doses of 200 rem or more of prompt radiation, 5 psi or higher blast overpressure, and10 cal/cm2 or higher thermal fluence. The centralized firestorm zone is indicated in orange,
within which there will be complete destruction and no survivors. The development of afirestorm is possible due to the high density of housing and other infrastructure, although thepresence of tall buildings casts some uncertainty on the results due to a current lack ofunderstanding as to what a firestorm might look like in a modern urban area.
Because the detonation is a relatively low-yield surface-burst, prompt radiation is estimated tohave a significant impact on the fatality count. In total, an estimated 220,000 deaths or 25% of
the 0.5 psi zone—not shown in Figure 6-7, but shown in Figure 6-8—will result within the days,
weeks, and months following the attack, depending on the physical injuries from destroyedbuildings and second and third-degree burns sustained by the victims. Around 30,000 of thesevictims are located within the 200-rem zone. Due to the high urban density of the Tokyo region,around 890,000 total people would be located within the 0.5 psi zone. Outside the 200-rem zone,
around 190,000 of these people could suffer fatal injuries or be killed by burns, building damage
due to blast overpressure, falling and flying debris, and other physical injuries. The effects of asurface-burst nuclear weapon would be somewhat shielded by a dense urban environment, but
the effects of urban tunneling between skyscrapers, the behavior of the skyscrapers themselves
when subjected to nuclear blast overpressure, and other factors, are not well understood,
contributing large uncertainty to these results. The effects of a nuclear detonation in a highly
dense urban environment should be studied further in future work.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

68Use Case 3• Nuclear Weapon Use by Terrorists• Target: Tokyo, Japan*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-7: A Single, 10 kT Nuclear Detonation in Central Tokyo, Japan, Estimated Likely
Deaths, and Estimated Cancers from Use Case 3.
Figure 6-8 shows the fallout simulation results for Use Case 3 on regional and local scales,
respectively. Since this detonation is a relatively low-yield surface-burst, and detonated in an
urban environment, fallout radiation exposure poses a large danger to the greater Tokyo region.
Fallout deposition patterns are highly weather-dependent, but in this scenario, the prevailingwinds blow to the east, centering on east Tokyo and reaching as far as Chiba prefecture. Within
hours and over the next few days, many people who do not remain sheltered could receive lethal
doses of radiation, experience acute radiation sickness, or be at a high risk of radiation-induced
cancer death in their lifetime.
Under this specific weather pattern, the population within the region of Tokyo including
Akihabara, Ueno Park, Asakusa, Tokyo Skytree, and much of Edogawa City would be at risk ofacquiring radiation doses in the range of 200 to 600 rem within a few hours to four days of thedetonation. Survival will be highly dependent on the availability and quality of medical care, andeven a large city such as Tokyo would likely not have the resources or hospital capacity to treat
victims outside of the areas immediately surrounding ground zero. The areas around Shibuya,
Shinjuku, and Tokyo Station will also be affected by very high levels of radiation, as well as
being partially located within the 0.5 psi zone (blue circle). These high levels of radiation could
result in as many as 1.6 million additional deaths within the following year, and 410,000 –
580,000 radiation-induced cancer deaths in the following decades.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

690.1 rem
5 rem

10 rem
100 rem
50 rem200 rem

200 rem(prompt)

0.5 psiFigure 6-8: Local and Regional Fallout Patterns Resulting from the 10 kT Surface-burst
Detonation in Use Case 3.

Uncompressed Edit-able graphic

Use Case 3 Implications:•

In a highly dense urban environment, many of the fatalities may occur at distances further
from ground zero due to flying and falling debris and to secondary fires stemming from
centrally located firestorms or directly ignited by thermal fluence itself. Nuclear weapon
effects in a modern urban area are not well understood, but the collapse of tall buildings ordebris falling from high heights may trap survivors and hinder search and rescue efforts, aswell as filling the air with dust and toxic smoke, increasing the number of fatalities eventhough the population may be somewhat shielded from the direct effects of the blast by thedense urban environment.

•

A surface-burst detonating in a dense urban environment could result in a huge number offatalities due to high radiation dose from fallout and could increase the number of radiationinduced cancer deaths far beyond the number of fatalities caused by impacts of thedetonation in the immediate and short-term.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

70

6.4 Use Case 4: “Conflict from Ukraine Spreads East”
The United States and its Western allies seek to restrain Russia from using nuclear weapons inNortheast Asia, but with few conventional assets to spare from the European theater, and at theurging of the ROK and Japan, the United States brings more nuclear weapons back into theregion, on submarines and ships, and places more nuclear-capable bombers in the region.
The combination of US actions and political and economic troubles at home cause Russian
leaders to order Russian nuclear forces in Northeast Asia, and likely Russian global nuclear
forces, to go to higher alert status. Ultimately, fearing a US attack, Russia attacks US militarybases in the region with nuclear weapons.
The United States responds to Russia’s attacks with nuclear attacks on Russian Far Eastern
nuclear bases. Further nuclear exchanges, as shown in Table 6-4, are averted by a combination of
diplomacy encouraged by the ROK and Japan, war fatigue, and political changes in Russia.

Table 6-4: Use Case 4 Nuclear Detonation Parameters“Conflict from Ukraine Spreads East”

Use Case
First User

RussiaUS Naval Base and Warships

First Use Targets

#1
#2
#3
#4
#5
First Responder
First Response
Targets

Type of
Location
HOB (m) Yield (kT)WeaponDelivery System
33.155, 129.713
1150
150 2-stage H bomb RSM-56 Bulava

Date and Timeof Attack*4/9/2024, 06:00

33.155, 129.731
33.155, 129.700
40.27, 137.95
40.27, 137.98

4/9/2024, 06:01
4/9/2024, 06:02
4/9/2024, 06:00
4/9/2024, 06:05

1150
1150
1300
1300

150 2-stage H bomb
150 2-stage H bomb
200 2-stage H bomb
200 2-stage H bombUS

RSM-56 Bulava
RSM-56 Bulava
RK-55 Granat
RK-55 Granat

Russian Naval Bases in the Far East

Location

HOB (m)Yield (kT)Type ofWeaponDelivery System

Date and Timeof Attack*#1#2

52.918, 158.49
43.111, 131.888

450
450

8 2-stage H bomb
8 2-stage H bomb

SBN W76-2
SBN W76-2

4/9/2024, 07:00
4/9/2024, 07:05#3
Additional
Detonations

43.081, 131.921

450

8 2-stage H bomb

SBN W76-2

4/9/2024, 07:06[None]

Use Case 4 begins with attacks by Russia on US bases in southern Japan and on US and allied
ships at sea. Figure 6-9 shows the number of estimated likely deaths resulting from these first use
detonations. Three 150 kT hydrogen bombs are detonated at a height of 1150 meters in thevicinity of a naval base in south Japan, and two 200 kT hydrogen bombs are detonated at 1300
meters above sea level in the vicinity of a US carrier group accompanied by a number of US andReducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

71

allied ships. Because it is difficult to simulate a nuclear attack on ships at sea, a total personnel
count of about 10,000 aboard was assumed.95 Half of the personnel on board are assumed toperish in the attack through a combination of damage to the ships, thermal fluence, and prompt
radiation exposure.
Firestorms are likely to occur following the cluster of three attacks targeting US naval bases
located in a populated area of southern Japan due to the high density of housing and otherbuildings. The occurrence of a firestorm is not possible at sea, but individual ships in the carriergroup would likely be set ablaze due to the intense heat from two high-yield fusion weapon
detonations.
The first phase of Use Case 4 results in a larger fatality rate to the local population than any
phase in previous use cases due to the effect of overlapping firestorm and prompt impact zones.
Forty-one percent of the population are killed within hours or days, and by the end of the year
following the attack. Over half of the population within the 0.5 psi zone do not survive.

Use Case 4• Attack by Russia on US militarybases in Japan, US Navy and allies’
ships at sea*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-9: Targets, Estimated Likely Deaths, and Estimated Additional Cancers from Use
Case 4, First Use Detonations.
Figure 6-10 shows first-use detonations by Russia and response attacks on Russian bases by theUnited States, and the resulting cumulative estimated likely deaths from those attacks. The
United States responds by detonating three low-yield weapons of 8 kT, which add 130,000
fatalities to the use case total, resulting in an overall likely death count of about 290,000.

95

Assumes attack is on a carrier battle group with some other US ships and/or allied ships also present, total of
10,000 personnel. For staffing carrier battle group, see, for example, United States Naval Reserve Intelligence
Program (undated), Ready-for-Sea Handbook: MODULE 2—CARRIER BATTLEGROUP & Amphibious Ready Group(ARG) PLATFORMS AND MISSIONS, available as https://irp.fas.org/doddir/navy/rfs/part02.htm

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 272

In the first phase of the use case, only high-altitude, high-yield (150 kT) detonations are usedover population centers, resulting in around 160,000 estimated deaths, 84% of which occur
within hours or days of the attack. On the other hand, the second phase of the use case sees only
the use of low-yield (8 kT) airbursts resulting in 130,000 estimated deaths, 40% of which occur
within hours of days of the attack. Unexpectedly, the number of deaths in each phase of theconflict is about the same. This result can be attributed to the fact that the population size in thevicinity of the high-yield airbursts is much smaller. This result, however, also shows that the
number of deaths due to a nuclear attack cannot be directly tied to the weapon yield or height-ofburst, and the death toll of a nuclear conflict can be unacceptably high even when only low-yield
nuclear weapons are used.
Another significant difference between this use case and other use cases evaluated is thepercentage of fatalities that occur within days as opposed to weeks or months. The high-yieldweapons, causing raging firestorms and featuring high thermal fluence over a broad area, inflictinstant death in a greater percentage of the victims (84%), whereas most victims of the low-yield
attacks will succumb to their injuries within the span of months to a year, and their survival rate
will be highly dependent on the availability of medical care. (This trend is also highly dependent
on the population distribution of the area. For example, results are different if populations are
clustered near ground zero or mostly located further away.

Use Case 4•

Attack by Russia on US militarybases in Japan, US Navy andallies’ ships at sea•

Response Detonations (3 total) by
the US on Russian naval bases*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-10: Targets, Estimated Likely Deaths, and Estimated Additional Cancers from
Use Case 4, First Use and Response Detonations.
Only the first use detonations on Japan result in fallout, and the weather conditions simulated
result in relatively little fallout over land, with people in the affected areas receiving relatively
low doses of radioactivity, as shown in Figure 6-11. It was estimated that 14,000-85,000 people
may die of radiation-induced cancer in their lifetimes. The fallout simulation resulted in a very
unexpected pattern, with the radioactive material from high-yield airbursts in southwest Japan
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 273

depositing onto the densely populated city of Osaka. Low levels of radioactive fallout also
spread to the east coast of China in the simulation.

Figure 6-11
resolution

Figure 6-11: Fallout Patterns resulting from First Use Detonations in Use Case 4.
Use Case 4 Implications:•

Clustered nuclear attacks with overlapping impact zones have a compounding effect on
the affected community; a higher percentage of the people in the affected area will notsurvive.

•

The intense, far-ranging heat due to the huge fireball produced by high-yield, highaltitude detonations and the firestorms produced by such an attack would result in total
and complete destruction of the area, likely killing over half of the population. The abilityof surviving residents to heal and rebuild the community would be severely inhibited, andeconomic impacts to the greater region would be significant.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 274•

Any detonation of high-yield, high-altitude weapons with devastating thermal andfirestorm impacts can wipe out entire communities and have a lasting generational
impact.

•Due to the variation in population size and density surrounding targets of nuclear
detonations, the number of fatalities does not always directly relate to the weapon yieldor height-of-burst. Since the number of people present in an area at any given time ishighly variable, the death toll resulting from a nuclear conflict is highly unpredictable,
regardless of the weapon yield that is used, and is unacceptably high even when only
low-yield nuclear weapons are used.

•

High-altitude, high-yield airbursts will result in very high prompt fatality rates—a highpercentage of the victims will die within hours or days of the attack.

•

Most victims of low-yield airbursts will succumb to their injuries within several weeks,months, or within a year following the attack, and their survival chance is highly
dependent on the availability and quality of medical care. This would place a highemotional, social, and financial burden on the surviving members of the community andon the nation as a whole.

•

High-altitude, high-yield nuclear weapon detonations can result in unpredictable andunexpected nuclear fallout patterns under certain weather conditions. Fallout can travel
great distances across oceans and international borders and affect large population centersfar from ground zero.

6.5 Use Case 5: “Not Going Well in Taiwan”
Changes in public opinion in an anti-leadership direction in China induce China’s leaders toattempt to distract its citizens by ordering an attack on Taiwan's perimeter defenses. The UnitedStates rapidly becomes involved militarily in the conflict and China suffers significant setbacks.
Worried about further involvement of US forces in the Taiwan conflict, China first threatens,
then—when threats appear to have little effect, and convinced that conventional defeat of its
attack on Taiwan is imminent—attacks US bases in the region, and US ships at sea, with one ormore nuclear weapons.
The United States responds with nuclear attacks on Chinese nuclear assets, including ICBM andother confirmed or suspected nuclear missile bases in China.
China launches counterattacks on military targets in the United States, and the United States
launches additional attacks on military targets in China. In both cases, some targets are in or
adjacent to urban areas. Even more extensive global nuclear war might well be considered thelogical result of this use case, but the analysis of this particular conflict has been limited to 24
total detonations, as shown in Table 6-5.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

75

Table 6-5: Key Parameters of Detonations for Use Case 5“Not Going Well in Taiwan”

Use Case
First User

China

US Naval and Air BasesFirst Use Targets

#1
#2
#3
#4
#5
First Responder
First Response
Targets

Location33.155, 129.713
13.59, 144.90
13.425, 144.679
26.355, 127.768
33.156, 129.732

HOB (m) Yield (kT) Type of Weapon
1150
250 2-stage H bomb
500
1150
1150
1150

250
250
250
250

2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb
US

Delivery System
DF-26

Date and Timeof Attack*10/8/2023, 06:00

DF-26
DF-26
DF-26
DF-26

10/8/2023, 06:30
10/8/2023, 06:35
10/8/2023, 06:20
10/8/2023, 06:10

Chinese ICBM Targets and Military Bases

Location

HOB (m)Yield (kT)Type of Weapon

Delivery System

Date and Timeof Attack*#1#2

36.601, 118.482
42.290, 92.525

450-5

8 2-stage H bomb
50 2-stage H bomb

SBN W76-2
B61-12

10/8/2023, 14:00
10/8/2023, 19:00

#3
#4
#5
#6
#7
#8
#9
#10
Additional
Detonations

42.290, 92.540
42.282, 92.550
42.29, 92.517
32.1686, 114.1258
40.324, 96.45
40.33, 96.45
40.33, 96.455
40.319, 96.445

-5
-5
-5
450
-5
-5
-5
-5

50
50
50
8
50
50
50
50

B61-12
B61-12
B61-12
SBN W76-2
B61-12
B61-12
B61-12
B61-12

10/8/2023, 19:00
10/8/2023, 19:00
10/8/2023, 19:00
10/8/2023, 19:30
10/8/2023, 19:00
10/8/2023, 19:00
10/8/2023, 19:00
10/8/2023, 19:00

#1
#2
#3
#4
#5
#6
#7
#8
#9

2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb
2-stage H bomb

Chinese Attacks on Additional US Bases, ICBM Exchange with China

Location
35.92, 126.62
37.085, 127.03
36.513, 103.606
34.06, 107.32
21.231, 110.445
61.253, -149.77
44.144, -103.08
36.96, -76.3
35.290, 139.660

HOB (m) Yield (kT) Type of Weapon
Delivery System1150
250 2-stage H bomb
DF-26
1150
250 2-stage H bomb
DF-26
1500
300 2-stage H bomb
W87 (ICBM)
1500
300 2-stage H bomb
W87 (ICBM)
1500
300 2-stage H bomb
W87 (ICBM)
1500
300 2-stage H bomb DF-5 (A or B), DF-31 (ICBM)
1500
300 2-stage H bomb DF-5 (A or B), DF-31 (ICBM)
1500
300 2-stage H bomb DF-5 (A or B), DF-31 (ICBM)
1300
200 2-stage H bomb JL-1 (SBL) or DF-21 (MRBM)

Date and Timeof Attack*10/10/2023,
06:20
10/10/2023,
06:30
10/12/2023,
03:00
10/12/2023,
03:10
10/12/2023,
03:20
10/14/2023,
02:20
10/14/2023,
05:40
10/14/2023,
06:50
10/15/2023,
21:00

Figure 6-12 indicates the target locations and estimated deaths and cancers resulting from thefirst use detonations in evaluated Use Case 5. In two of the attacks, two weapons were detonatedclose together to destroy key capabilities of close-by military bases. Hundreds of thousands ofdeaths in Japan and Guam were estimated to result from such attacks.
The two overlapping detonations in Sasebo Naval Base in the south of Japan will likely cause alarge firestorm within the area affected by 15 cal/cm2 or more of thermal fluence due to the highdensity of housing and other buildings. In Guam, the occurrence of a firestorm will likely be
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 276

avoided, owing to the sparsity of infrastructure and proximity to the coast, although local fires
and forest fires will occur. In Okinawa, the detonation of a 250 kT airburst will likely cause afirestorm to develop due to the high density of infrastructure in parts of the 15 cal/cm2 zone.

Use Case 5• First Use Detonations: Attacks by
China on US bases in Japan andthe Republic of Korea*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-12: Targets, Estimated Likely Deaths, and Estimated Additional Cancers
Resulting from Use Case 5, First Use Detonations.
Figure 6-13 shows the cumulative impact of both first use and response detonations in Use Case
5. Many of the response detonations target remote and unpopulated missile sites in western
China, but some are in or near urban areas. An estimated 570,000 deaths would result from firstuse and response detonations in this use case, with an additional 400–19,000 short-term deaths
due to high fallout radiation, and 5,000–15,000 long-term, radiation-induced cancer deaths. As
the conflict escalates, the primary nuclear weapon impact causing an increase in the number offatalities is nuclear fallout. Even when nuclear weapons are detonated in areas that appear to be
remote, there are oftentimes nearby communities that may be severely affected by nuclear fallout
levels.
Most of the attacks carried out in the response detonation phase of Use Case 5 target remoteareas covered by sparse vegetation or desert. At one missile site in China, the occurrence of afirestorm is possible due to the clustering of infrastructure near ground zero.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

77

Use Case 5• First Use Detonations: Attacks by
China on US bases in Japan andthe Republic of Korea• Response Detonations: Attacks by
the US on Chinese nuclear andmilitary bases*Individual impacts may not add up to theexact Total shown due to rounding.

Figure 6-13: Targets, Estimated Likely Deaths, and Estimated Additional Cancers
Resulting from Use Case 5, First Use and Response Detonations.
Finally, Figure 6-14 shows the cumulative estimated likely deaths resulting from all first use,
response, and additional detonations in Use Case 5. An estimated 2.6 million victims would
likely die within one year because of the immediate impacts of this global nuclear conflict, withan additional 400–19,000 short-term victims of high radiation dose exposure. Tens to hundredsof thousands more could die from radiation-induced cancers in their lifetime.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

78

Use Case 5• First Use Detonations: Attacks by
China on US bases in Japan andthe Republic of Korea• Response Detonations: Attacks by
the US on Chinese nuclear andmilitary bases• Additional Detonations: Attacks by
China and the US on theiradversary’s nuclear and military
bases*Cumulative with First-Use and Response Detonations.
Individual impacts may not add up to the exact Total shown
due to rounding.

Figure 6-14: Targets, Estimated Likely Deaths and Estimated Additional Cancers
Resulting from Use Case 5, All Detonations.
Figure 6-15 through Figure 6-17 show simulated fallout patterns from first use, first use andresponse, and all detonations in Use Case 5, respectively. Radioactive material and contaminatedsoil particles are spread across much of south and east Asia by the end of the conflict, including
to many countries politically and militarily uninvolved. South Japan, parts of China, Southeast
Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

79

Asia, Taiwan, and other Pacific islands were affected by significant levels of radioactive fallout–
mostly non-lethal, but enough to increase the cancer risk in some populations and will thus havefar-reaching political consequences. Although covered by Nuclear-Weapon-Free treaties or selfdeclared nuclear-weapon-free zones, the Philippines, Mongolia, Laos, Myanmar, Thailand,
Vietnam, and many Pacific islands are affected by radioactive contamination from fallout.

Figure 6-15: Fallout Pattens for First Use detonations in Japan and Guam in Use Case 5.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

80

Figure 6-16: Fallout Pattens for First Use and Response Detonations in Japan, Guam, andChina in Use Case 5.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

81

Figu
reso

Figure 6-17: Fallout Pattens for All Detonations in Asia in Use Case 5.
Use Case 5 Implications:•

Even attacks in “remote” areas can have fatal effects on nearby populations due to thedispersion of highly radioactive nuclear fallout. Areas that seem remote are, in reality,
home to communities of people who live far from city centers and may not have timely
access to the medical care required to prevent acute radiation fatalities and treat radiationinduced leukemia and cancer.

•

As a nuclear conflict escalates, even if the same number of nuclear weapons aredetonated from one phase of the conflict to the next, the weapon yields used may
increase, disproportionately magnifying the number of fatalities by 4-5x or even more,demonstrated by the results of the Use Case 2 and Use Case 5 simulations.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 282•One of the greatest unintended consequences of nuclear war is the spread of nuclear
fallout. Regional nuclear conflict can escalate to global nuclear conflict when significant
levels of radioactive fallout cross international borders, even dragging countries in
Nuclear-Weapon-Free Zones into the conflict, which can have significant politicalconsequences and could weaken international nuclear nonproliferation treaties.

6.6 Conclusion: Overall Summary of Simulated Use case Results and Implications
Low-Yield Nuclear Weapons (20 kT or less): Surface-burst low-yield nuclear weapons canresult in international cross-border nuclear fallout, unintentionally dragging allies andadversaries into the conflict, which can have severe political consequences and spread fear inmembers of the public due to a lack of understanding of nuclear fallout and the biological effectsof radiation. Very low-yield weapons are more likely to be surface-bursts, in which case prompt
radiation and high radiation from nuclear fallout can have a large impact on the death toll of aconflict. In the case of low-yield airbursts, most victims will succumb to their injuries withinseveral weeks, months, or a year following the attack, and their survival chance is highly
dependent on the availability and quality of medical care. This would place a high emotional,social, and financial burden on the surviving members of the community and nation.
Firestorm / High-Yield Airburst Impact: As the weapon yield increases, the impact offirestorms increases, which disproportionately decreases the survival chance of affected
populations. Not only does the fatality count increase as a result of firestorms, but also a higher
percentage of the people located within the 0.5 psi zone surrounding the target will die, resulting
in even greater economic and social consequences, making rebuilding from the disaster evenmore painful and difficult for survivors. In the case of clustered detonations, firestorms fromhigh-yield, high-altitude detonations would result in total and complete destruction of the area,
likely killing over half of the population within the 0.5 psi zone. The ability of surviving
residents to heal and rebuild their communities would be severely inhibited, causing major
economic impacts to the greater region, and possibly wiping out entire local communities andproducing lasting generational impacts.
International Cross-Border Nuclear Fallout: Low-yield surface bursts and high-yield surface
or airbursts can result in significant levels of regional fallout that cross international borders,even dragging regions covered by Nuclear-Weapon-Free treaties into the conflict, which canhave significant political consequences and weaken international treaties. Even low levels of
fallout can decrease trust in alliances and spread fear in members of the public due to a lack ofunderstanding of nuclear fallout and the biological effects of radiation.
Conflict Escalation: The attacks of responding adversaries tend to be more lethal than first-use
attacks as the conflict escalates. If the first-response detonation is a surface-burst, it may spur theadversary to also respond with one or more surface-bursts. If the responding adversary increases
the yield of their surface-burst, especially in a populated area, the death toll due to both promptand fallout radiation can drastically increase. In Use Case 2, population centers are attacked in
the response detonation phase as opposed to remote targets, and weapons of increasingly larger
and larger yield are detonated as the conflict escalates. As a nuclear conflict escalates, even if thesame number of nuclear weapons are detonated from one phase of the conflict to the next, theweapon yields used may increase, disproportionately magnifying the number of fatalities by afactor of four to five or even more.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

83

Urban Targets: In a highly dense urban environment, many fatalities may occur at distances
further from ground zero due to flying and falling debris and to secondary fires stemming from
centrally-located firestorms. The collapse of tall buildings or debris falling from high heights
may trap survivors and hinder search and rescue efforts, as well as filling the air with dust andtoxic smoke, and increasing the number of fatalities even though the population may besomewhat shielded from the direct effects of the blast by the infrastructure.
Vulnerability of Remote Communities: Even attacks in “remote” areas can have fatal effects
on nearby populations due to the dispersion of highly radioactive nuclear fallout. Areas that seem
remote are home to communities of people who live far from city centers and may not havetimely access to the medical care required to prevent acute radiation fatalities or to treat
radiation-induced leukemia and cancer.
Unintended, Unpredictable, and Uncertain: Due to the variation in population size and density
surrounding targets of nuclear detonations, the number of fatalities from a given attack does notnecessarily directly relate to the weapon yield or the height-of-burst. As the number of people inan area at any given time is highly variable, for example, as commuters move from offices tohome and back, the death toll resulting from a nuclear conflict is highly unpredictable, regardlessof the weapon yield that is used, and is unacceptably high even when only low-yield nuclear
weapons are used. High-altitude, high-yield nuclear weapon detonations can result in
unpredictable and unexpected nuclear fallout patterns under certain weather conditions, andfallout can travel great distances across oceans and international borders and affect large
population centers far from ground zero. One of the greatest unintended consequences of nuclear
war is the spread of nuclear fallout. Regional nuclear conflict can escalate to global nuclear
conflict when significant levels of radioactive fallout cross international borders, resulting inunintended political consequences.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 284

Glossary
Becquerel (Bq)

SI unit of radioactivity, equal to 2.703 x 10-11 Curies (Ci).

Cal/cm2

Calories per square centimeter, a measure of thermal (heat) fluence. One
calorie equals 4.184 Joules (J).

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,”96 such as
using the threat of use of nuclear weapons to deter an attack by another withconventional or nuclear weapons.

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.

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.”97

FirestormFirestorms are mass fires with particular characteristics. In a firestorm, a large
enough contiguous area is set aflame, effectively at once, that the fire creates
its own wind patterns. As heat from the fire rises, winds arise on all sides
traveling toward the fire, sometimes at gale-force velocities of up to 90 miles
per hour (about 40 meters/second).

96

Brittanica.com (probably 2017), “Deterrence, political and military strategy,” available ashttps://www.britannica.com/topic/deterrence-political-and-military-strategy
97
Atomicarchive.com (2020), “Radioactive Fallout,” available ashttps://www.atomicarchive.com/science/effects/radioactive-fallout.html

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

85

Fission

In nuclear fission, an atom splits into two smaller atoms, releasing energy. A
nuclear fission bomb relies on fission for its destructive power, using uranium
enriched in the isotope U-235 or plutonium as the fissile material.

FusionIn nuclear fusion, two smaller atoms, typically heavy isotopes of hydrogen,are forced together to form a larger atom, releasing energy. Nuclear fusionbombs use fusion reactions, typically as a second stage in a 2-stage weapon, toprovide their destructive power.

Gray (Gy)

Unit of ionizing radiation dose in the International System of Units (SI),defined as the absorption of one joule of radiation per kilogram of matter (forexample, human tissue).

H-bomb

A two-stage nuclear weapon (thermonuclear) where a nuclear fission primarystage ignites a secondary nuclear fusion stage.

HEMPHigh Altitude Electromagnetic Pulse. A 2008 Report by the United States
Congressional Research Service (2008), for example,98 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.”99 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.

Joule (J)Measure of energy in SI units equal to one kg-m2/s2, or one N-m (Newtonmeter).

Kiloton (kT)A 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.

98

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.
99
Arms Control Association (2019), ibid.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

86

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.

Mass FireInteractions occurring when large areas are ignited and burning
simultaneously.100

Megaton (MT)A measure of the explosive power of a nuclear detonation equal to 1000
kilotons.

NEA

Northeast Asia.

NPT

Treaty on the Non-Proliferation of Nuclear Weapons.101“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).102

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).

Prompt Effects

Impacts of a nuclear detonation occurring within a short time of the explosion,
typically within seconds, minutes, or hours, but sometimes including deaths
caused by the detonation but with victims not succumbing for days or weeks.

psiPounds per square inch (English units) measure of overpressure.

radUnit of absorbed ionizing radiation dose, defined as 1 rad = 0.01 Gray or 0.01
J/kg of body mass deposited by X-rays or gamma rays.

rem“Roentgen equivalent man,” defined as the dosage of radiation in rads that isthe equivalent of one rad.

100

Mark A. Finney and Sara S. McAllister (2011), ibid.
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/
102
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.”
101

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

87

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).

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.103

ROK

Republic of Korea.

Sievert (Sv)

Unit of absorbed ionizing radiation, equal to 100 rem.

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 ROK during andafter the Korean War.104

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.
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).

103

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
104
See, for example, UN Command (undated) “Under One Flag,” available as https://www.unc.mil/About/AboutUs/

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

88

ANNEXES
Annex 1: Nuclear Use Cases Developed During and Subsequent to Project
Year 1 from which Evaluated Use Cases Were SelectedSuite of use cases developed during and subsequent to project Year 1, and criteria
for selecting use cases for further analysis
Presentation of use cases
Table A1-1 provides an overview of the key elements of the use cases presented in the Year 1
Report, plus the additional Russia as First User cases described above, and how the use cases are
related. Details of these use cases are provided in the Year 1 Report (and above).
Use cases shaded in red are those that have been selected for quantitative analyses, as described
below, and also appear with yellow check marks in Figure A1-1.
We emphasize that although we have designed these use cases to be plausible, they only provide
examples of an essentially infinite set of potential circumstances in which nuclear weapons use
could occur in the region. Moreover, each of these use cases could evolve in a multitude of ways,
potentially involving different actors and targets. The 30 total use cases that we present below,
and the five cases we evaluate quantitatively in this Report, are thus only a few examples of thewide and deep range of possible illustrations of what might happen once a nuclear conflict
begins. We definitely do not assess that these use cases are likely, rather we posit and evaluate
them here only to help learn about and demonstrate the potential range of impacts that a nuclear
conflict might have, and ultimately, how policies to avoid nuclear use in the first place might be
developed and implemented.

Reducing the Risk of Nuclear Weapons Use in Northeast Asia (NU-NEA), Project Year 2

89

Table A1-1: Summary of Use Cases Considered
Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Uncertainties, Ultimate Outcome,
Policy Lessons“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.

US/UN Commandconventional attack on DPRK
forces near DMZ, US nuclear
attack on nuclear weapons
targets in DPRK.

High-level US mission
reassures China andRussia, engagement keeps
exchange limited, leads todiplomacy, DPRK opening.

Would US/ROK be able to refrainfrom attacking DPRK leadership?

“We're Still Here”
Variant 2

As above, but DPRK attack notcarried out due to malfunction
or timely, successful
negotiation.

US/UN Command develop
counterattack plan, but do not
implement because of
successful diplomacy.

China and Russia support
DPRK engagement withinternational community,
diplomacy re-starts.

“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.

United States uses nuclear
and conventional (with ROK)
weapons on DPRK military andnuclear targets, in part at
insistence of ROK and Japan.

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.

Would Russia and China be willingto stay out of the war?

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.

US responds withconventional attacks on
military installations, nuclear
weapons on ICBMs and othernuclear sites and on
Pyongyang command bunker.

DPRK nuclear mines on DMZ mightleave Peninsula divided and badly
damaged.

As above, but with fraying of
US/ROK Alliance.

As above, with US nuclear
attack depending on analysis
of DPRK ICBM capability at thetime.

Remaining DPRK
leadership offers terms forceasing military conflictwith international accessto and control over DPRK’s
nuclear weapons in
exchange for “MarshallPlan” for the DPRK.

“The Best Defense isa Good Offense”
Variant 1“The Best Defense isa Good Offense”
Variant 2

90

China and Russia stay outof war, but demand say ingoverning DPRK, maybe
through UNSC.

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 the Europe and others in theinternational community be able tomediate a crisis of this magnitude?

Defeated 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

Uncertainties, Ultimate Outcome,
Policy Lessons“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.

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,
planes.

Additional to the above, lessons
related to reactor security,
provision of backup power forreactors, military, civilians that is
separable from the main grid.

“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.

China and Russia mass
troops at DPRK border,
with some incursion by
China, but no nuclear
response.

May not be probable that
USFK/ROK refrain from attacking
DPRK leadership.

“Last Option for
Survival” Variant 2

Perceived or actual DPRK
provocation spurs US/ROK
conventional attack on DPRK
leadership, induces DPRK
nuclear use on ROK.

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

Attack on Pyongyang
causes China to at least
threaten United Stateswith ICBMs.

“We’ve Got Them
Where We Want
Them”

DPRK takes advantage of slowmoving talks to invade ROK,
nuclear attack on US bases in
ROK, Okinawa.

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.

Would DPRK attack whilenegotiations underway? Would
DPRK discount US counterattack
possibility? Could US counterattacks
be mistaken for attacks on China or
Russia?

“Help Not Wanted”

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

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

Would DPRK fear China enough toattack with nuclear weapons?

91

Will China be compelled to protect
DPRK?
Lessons: Monitor conditions in
DPRK, offer humanitarian support(international community).

Would US/ROK troops come to theaid of northern DPRK rebels?

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

launches nuclear attack on
China.
“The Best Defense isa Good Defense”“US Leadership
Hubris”“Response to DPRK
Proliferation”

Use Case Consequences
Peninsula governancewith China, Russia.

Uncertainties, Ultimate Outcome,
Policy Lessons
Would Chinese nuclear strikes be
mistaken by United States/Japan?

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.

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.

Could US PGM weapons be
deployed in time?

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.

China attacks withconventional weapons tokeep US/ROK south of
DMZ. If DPRK leadership
attacked, China might
attack United States with
nuclear weapons.

Lack of communication by US/ROKwith China/Russia might cause themto use nuclear weapons, trending
toward global conflict.

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.

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

Would ROK condone attack on
DPRK?

Possible DPRK attack on a
Japanese reactor to cause
chaos, induce truce.

92

Would the particular US president
in power at the time use nuclear
weapons first?

Lessons: Maintain secure
procedures for war authorizationthat include those outside ofleader’s inner circle; consult withboth allies and potential
adversaries.

Could nuclear forensics lead theUnited States to conclude that DPRK
was responsible for original attack?

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Uncertainties, Ultimate Outcome,
Policy Lessons

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.

DPRK 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
Okinawa.

How would DPRK respond to lategame change in US diplomacy?

After worsening relations withJapan, DPRK launches HEMP
over Tokyo, Japan demands
United States respond with
nuclear attack targeting DPRK
leadership to remove possibilityof counterattack.

With 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.

Original DPRK HEMP
attack allows China toconsider US nuclear attack“provoked.”

Could US attack modes (missiles
from bombers, submarines, ships)
be mistaken by China, Russia, forattacks on them?

China (and Russia) go on
alert, but do not directlyintervene.

Major refugee crisis in the region
likely (ROK and DPRK).

“A Promise is a
Promise” Variant 2

As above, but ROK is focus of
DPRK HEMP.

“A Promise is a
Promise” Variant 3

As in Variant 1, but DPRK
delivers chemical and/or
biological weapons to Japan.

US renews attack onleadership with larger,
penetrating weapons.

“Tripped at theFinish Line”“A Promise is a
Promise” Variant 1“Not Going Well in
Taiwan”

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.

Would China join if fallout damaged
NE China?
Would United States correctly
identify DPRK brinksmanship andseek to reduce tensions?

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 triggering attack.

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

93

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.

Unclear 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

Uncertainties, Ultimate Outcome,
Policy Lessons“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.

United States, encouraged by
Japan, attacks Russian PacificFleet headquarters and otherRussian bases in the East.

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

What standing orders would
Russian Federation (RF) submarine
commanders revert to in times ofcrisis?

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,
automated nuclear launchsystem mistake ROK spacelaunch for nuclear attack on
Russian bases, leading tolaunches on US bases in ROK.

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
ROK.

Arms control talks are
reinvigorated, as are
security talks with theDPRK;DPRK economic reform
initiated, Russian politicaland military reform
begins.

Could a solar storm really affectRussian systems sufficiently tocause error? Could a US president
be convinced to refrain from acounterattack?

Possibly forewarned of theattack, US/NATO leadershipset nuclear and conventional
forces on high alert, andincrease sanctions, but do notlaunch a nuclear
counterattack.

Additional detonations of
nuclear weapons justavoided via intense
negotiation, which, alongwith increased Russian
economic problems anddissent, force settlementof Ukraine conflict.

Could war really be avoided
following a Russian Detonation?
Would China take the opportunity
to move on Taiwan? What positions
would Japan and the ROK take on
escalation? Could the Ukraine
conflict really come to a resolution
as in variant 1?

“Dead Hand Error”“Sending a Message,
Eastern Doorstep”
Variant 1

Russia attacks US Bases in
ROK, elsewhere.

94

Lessons: Raise awarenessCommunications among militaries
about interpretation of perceived
actions.

Lessons: Use extreme caution inusing artificial intelligence in nuclear
launch systems and improve
nuclear-related communications
between nuclear weapons states.

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Uncertainties, Ultimate Outcome,
Policy Lessons“Sending a Message,
Eastern Doorstep”
Variant 2

Reversals of Russian military
gains in the Ukraine conflict,plus the results of expanding
dissent in Russia due to physicaland economic hardships related
to sanctions against Russia andthe effort needed to sustain theconflict, cause Russian
leadership to conclude that only
nuclear weapons can reverse
Russia’s declining militaryfortunes and allow a face-saving
conflict settlement.

United States/NATO/Japan
believe the attack is meant asa prelude to an attack on
military or civilian targets in
the Far East, launch nuclear
attack in reprisal on Russian
Pacific Fleet targets

US attacks/Russiancounterattacks bring on
exchanges of ICBMs
causing wide devastationin the US, Europe, Russia,
and Northeast Asia,
cripple world economy

Lessons: Importance of building
mechanisms for communications
between adversaries aggressive
launch is perceived, and to limit
second strikes.

“Conflict from
Ukraine Spreads
East”

To restrain Russia from using
nuclear weapons in Northeast
Asia, the United States bringmore nuclear weapons backinto the region, causing Russian
nuclear forces in the region to
go to a higher alert status, andultimately, to attack US military
assets with nuclear weapons.

United States launches atactical nuclear attack on a
Russian submarine base in theregion, destroying the base as
well as several surface vessels
and submarines in port at thetime.

US leadership announces
targeting of key militaryand leadership locations in
Russia, invoking of Article
5 of the NATO treaty.
NATO forces move toward
Western Russia but stop
when Russia stands down
its nuclear forces.
Ultimately, domesticchanges in Russia end theconflict without further
nuclear use.

Would the United States stop at thedestruction of Russian Far Eastbases and submarines? Would
Russian nuclear forces hold theirfire after the first nuclear exchange?
How would Russian leadership
respond to the situation? How do
China, Japan, and the ROK respond?

95

Lessons: Important roles of militaryto-military communications
between adversaries, restraint on
using nuclear weapons by civilian
leaders, communications between
nations throughout bothgovernment and civil society if there
is a major upheaval in leadership.

Use Case Title

Triggering Events and First Use

How the Conflict Evolves

Use Case Consequences

Uncertainties, Ultimate Outcome,
Policy Lessons“Broken Promises
Leads to Breakout”
Variant 1

New, 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.

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

ROK breakout also possible undersimilar conditions.

“Broken Promises
Leads to Breakout”
Variant 2

For similar reasons to theabove, the ROK develops
nuclear weapons, uses low-yield
warheads to strike at DPRK
leadership.

As above, but with attacks
focused on ROK
infrastructure.

Attack fractures
ROK/Japan relationship,
United States caught in
middle.
China intervenes to slow
flow of DPRK refugees
with Chinese troops in
DPRK.

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’srequest.

Renewed attention on
nonproliferation andantiterrorist initiatives.

Domestic terrorist organization
detonates warhead in Chinese
city.

China attacks ethnic enclaves
within China, possibly with
nuclear weapons, mightassume United States wasbehind attack and launch at a
US carrier group sailing in theregion.

China could obtainsympathy frominternational community,
depending on whether it
decides upon harshcollective punishment.

Nuclear Weapons
use by Terrorists,
Potential Variant 2

96

ROK takes lead in
rebuilding the Korean
peninsula if not too badly
damaged.

If DPRK blamed, series ofnuclear exchanges UnitedStates to DPRK, DPRK toregion and/or to UnitedStates.

Lessons: Unwise to think that entire
DPRK nuclear arsenal can be
destroyed by a targeted attack.
Also, it may be unwise to expectthat the DPRK population will
embrace the ROK as the victor in a
conflict between the Koreas.

Use Case Title
Nuclear Weapons
use by Terrorists,
Potential Variant 3

Triggering Events and First Use
Cyberwarriors attack nuclear
command-control, launches
nuclear missile from China,
Russia, or United States.

How the Conflict Evolves
Varying evolution dependingon when launch is detected,
whether hacked nation warns
targets, whether targetednation assumes attack to havebeen launched on purpose bynation owning missiles.

Use Case Consequences

Uncertainties, Ultimate Outcome,
Policy Lessons

If attack was assumed
deliberate by targetednation(s), result is
probably an escalating
series of exchanges.

Would terrorist group beintercepted before detonation ofdevice? If so, more emphasis on
non-proliferation efforts, disruptionof nuclear black market worldwide.

Other paths of evolution
yield frantic diplomacy,
more attention on
safeguards, disarmament.

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

97

Sending a essage
Eastern oorstep

E tent of Nuclear Use
NUDET oided
Single Weapon
LimitedLimited to E tensi e
E tensi e

11

Conflict from
Ukraine Spreads
East

Selected for nal si s
Figure A1-1: Nuclear Use Cases Assembled and Considered, and Use Cases Selected for Analysis

98New use cases developed after Project Year 1 incorporating lessons from
Ukraine Conflict
The (virtual) ink was barely dry on our Year 1 Report when the Ukraine conflict presented a setof circumstances that had not been fully anticipated among the set of 27 Year 1 Use Cases. These
new circumstances suggested that the relatively few plausible use cases with Russia as the firstuser of nuclear weapons needed to be augmented, given what Russia’s actions and statements in
the Ukraine conflict might portend for its actions in NEA.
Although the lessons of the war in Ukraine are yet, as of this writing, to be fully learned, both by
Russia and by the rest of the world, it is clear that nuclear war involving Russia is getting much
more consideration than it was at the beginning of 2022. How might Russia’s experience in
Ukraine change how it might become a first user of nuclear weapons in NEA? The “Sending a
Message, Eastern Doorstep” and “Conflict from Ukraine Spreads East” cases, provided below,
develop two possibilities. These cases augment those presented in the Year 1 Report, namely:•“Threats to Russian SSBN Bastions” case, in which a Russian submarine commander isconfused by what is perceived to be a nuclear attack but is actually a weapons test or an
exercise, and, unable to corroborate the situation with Pacific Fleet command, follows
existing rules of engagement (ROE) and fires nuclear weapons on a US base in theregion; and•“Dead Hand Error,” in which the growing capabilities of artificial intelligence (AI) as
used in nuclear command and control by Russia, coupled with consideration of the 1980s
Soviet “Dead Hand” system for launching nuclear weapons if military leadership wereincapacitated, posits an accidental use of nuclear weapons when the AI system relied
upon (in part, at least) by Russia to launch a retaliatory nuclear strike becomes convincedthat enemy weapons are incoming and launches nuclear weapons in response.

“Sending a Message, Eastern Doorstep”
The combination of attrition and eroding morale in its armed forces, as the war with Ukraine
continues, together with growing uncertainty about prevailing in the war and alarm about theNATO expansion that the war has induced, convince Russian leadership that only a nuclear
detonation will allow it to negotiate an end to the war from a position of strength. Not wishing touse a nuclear weapon nearer to its own population centers in Eastern Europe (or near to NATOterritory), it chooses the waters off the Russian Far East for a demonstration high-altitude nuclear
detonation, delivered by a long-range missile (an ICBM) fired from a base in Siberia.105 This
detonation is in form similar to a nuclear test, but would mark the first time in nearly 60 years
since the signatories of the Limited Test Ban Treaty of 1962, and over 40 years since any nation,

105

This use case draws from ideas in Gregg Herken, Avner Cohen, and George M. Moore (2022), “Scenarios for
How Putin Could Actually Use Nukes: Here’s how to think about the unthinkable,” Politico, dated May 16, 2022,
and available as https://www.politico.com/news/magazine/2022/05/16/scenarios-putin-nukes-00032505. The
authors of the Politico piece chose as the first of their scenarios a high-altitude, low-yield explosion over the old
Soviet nuclear testing area of Novaya Zemlya, about 2000 km north and east of Moscow, but only about 1000 km
from the territory of new-NATO-members-to-be Sweden and Finland (and of NATO member Norway).

99

has detonated a nuclear weapon in the atmosphere.106 This nuclear first use would be categorizedat the “deliberate” or “intentional” end of the spectrum.107
Triggering Events and First Use
As 2022 passes, the Russian invasion of Ukraine continues to make little headway. By the fall of
2022 Ukrainian forces, bolstered by weapons and supplies from the West, begin little by little totake back territory from Russian forces that are not receiving supplies and reinforcements as
inspected, in part because of economic difficulties at home caused by sanctions on the Russian
economy by Western nations. In early 2023, Russian forces are pushed back out of the destroyed
port city of Mariupol, reversing a hard-won victory from May of 2022,108 and once again cutting
off land routes to the annexed Crimean Peninsula. Two more major warships of the RussianBlack Sea Fleet are destroyed by Ukrainian forces.
These reversals, plus expanding dissent in Russia as winter arrives and economic hardships
related to sanctions and the effort needed to sustain the conflict in Ukraine take their toll on the
Russian population, cause an increasingly reclusive Vladimir Putin, the Russian leader, toconclude that only nuclear weapons can reverse Russia’s declining military fortunes and put
Russia in position for a face-saving settlement of the conflict. Calculating that a nuclear
detonation in Europe, even if in a remote Arctic location such as the Soviet era test site in
Novaya Zemlya, would result in sufficient outcry internationally—and perhaps more crucially, athome—that a settlement, and regime survival, would be out of reach,109 Putin orders a highaltitude (but atmospheric) detonation of a low-yield nuclear weapon (from Russia’s large arsenalof tactical nuclear weapons) in the waters off of the Russian Far East.110 The site chosen, farfrom both NATO and almost all of the Russian population, is in the North Pacific, about 1000
km east (outside of) the Sea of Okhotsk, about 500 km south of Kamchatka, and therefore only
slightly closer to Russian territory than to the easternmost US Aleutian island, Attu. The weapon
is delivered by a “Sarmat” ICBM launched from a base in the Krasnoyarsk area, to which these106

See, for example, United Nations (undated, but after 2017), “International Day against Nuclear Tests: 29
August”, available as https://www.un.org/en/observances/end-nuclear-tests-day/history
107
Note that for the purposes of this case we are considering this high-altitude detonation as a “first use,”although this designation is different than was used in the NU-NEA project Year 1 Report (Possible Nuclear Use
Cases in Northeast Asia: Implications for Reducing Nuclear Risk) for a similarly-provocative high-altitude nuclear
detonation by the DPRK. In the Variant 1 version of the “A Promise is a Promise” case in the Year 1 Report, forwhich the United States is called the first user, the US response is to a high-altitude electromagnetic pulse (HEMP)
from a DPRK nuclear weapon detonated over Japan. We make a change in nomenclature for this Russian first use
case in part due to a reconsideration, informed by input from other researchers, of what types of nuclear
detonations ought to be defined as first use.
108
See, for example, Reis Thebault, Paulina Firozi, Paulina Villegas, Amy Cheng, Jennifer Hassan, Ellen Francis,
Andrew Jeong, and Julian Mark, “Ukraine abandons defense of besieged steel plant,” Washington Post, dated May
17, 2022, and available as https://www.washingtonpost.com/world/2022/05/17/russia-ukraine-war-news-liveupdates/
109
Another possible trigger for Putin to order such a detonation might be his fear of an impending coup within the
Kremlin, and/or pressure from Kremlin insiders to demonstrate Russian capabilities and resolve.
110
Although such a detonation has not been carried out in 60 years by the United States or Russia, it is not
unprecedented. See, for example, Rod Lyon (2017), “Nuclear tests involving ballistic missiles with live warheads,”
Australian Strategic Policy Institute, The Strategist, dated 7 December 2017, and available ashttps://www.aspistrategist.org.au/nuclear-tests-involving-ballistic-missiles-with-live-warheads/

100missiles were to have been deployed in 2022.111 The commander of the missile base at firstrefuses the order to fire, but is overruled, and perhaps even relieved of duty, by a Federal
Security Service officer who has been recently posted at the base in case of such an eventuality,
placed there based on his loyalty to Putin. The detonation is designed to both serve as ademonstration of the newly-deployed weapon and as a warning to the United States and its allies.
The remoteness of the blast site, the size of the weapon, and the altitude of detonation result in
little damage to human infrastructure on the ground, and the resulting radiation, althoughdispersed worldwide, results in low enough concentrations so as not to cause significant humanhealth concerns. A number of aircraft transiting in the area are affected by the EMP from theweapon, with two Japanese fighter jets on patrol and a trans-Pacific airliner, the daily Korean Air
flight KE 24, heading for Inchon from San Francisco, each passing close enough to the blast tocompromise their control systems, ultimately crashing into the sea with pilots and passengers
killed.
How the Conflict Evolves
Following the launch of the ICBM, Putin orders submarines based in the Sea of Okhotsk to go to
the open ocean, both to signal Russian resolve and to better protect the submarines from potential
counterattack, enhancing their survivability and preserving them for a potential follow-on strikeshould the United States and its allies retaliate to the atmospheric detonation. From that point
there are many possible variants as to how the conflict might evolve, of which two are described
below.
Variant 1: Restraint
Perhaps tipped off in advance by trusted Russian sources that a nuclear detonation is imminentand is intended as a demonstration, not an attack, US and NATO leadership do not immediately
assume that the missile launch is an attack, and set nuclear and conventional forces on high alert
but do not launch a nuclear counterattack. Rather, and following the conclusions offered from theauthors of the May 2022 Politico article,112 US leadership, in consultation with other Western
leaders (NATO) and those of Japan and the ROK, consider a nuclear response, but ultimately
choose to “rally the nations of the world in a universal condemnation of Putin for breaking thenuclear taboo and taking the most dangerous first step toward a nuclear war.” This would include
doubling down on economic sanctions on Russia, doing everything short of physical attack on
Russian assets to disable key military and economic infrastructure, and increasing military aid to
Ukraine.
It is likely that the United States and its allies would only exercise this kind of restraint if leaders
were in possession of reports that persuasively confirm that Russian intentions in ordering thenuclear detonation are in fact well-understood, which may require that the intelligence is in fact
sourced from an individual who is known (by intelligence sources) to be fully briefed on Russian
nuclear strike decision-making.113
111

The flight from Siberia to the target site, at around 4500 km (ground distance), would be well within the 35,000
km (22,000 mile) range of the Sarmat ICBM. See, for example, Al Jazeera (2022), “Russia to deploy new
intercontinental nuclear missiles by autumn”, dated 23 April 2022, and available ashttps://www.aljazeera.com/news/2022/4/23/russia-to-deploy-sarmat-missiles-in-major-nuclear-upgrade
112
Gregg Herken, Avner Cohen and George M. Moore (2022), ibid.
113
In this variant of this use case, intelligence assurances at a sufficient level to keep Western leadership from
responding militarily likely implies that someone in the Russian leadership inner circle would be passing

101Faced with increased success by the Ukraine military, Russian troops start to leave their posts. At
home, facing crippling sanctions and with economic difficulties very much in evidence ineveryday life, pressure mounts for Russian leadership to step down, and after Putin disappears
from public view, more moderate elements within the existing Russian leadership signal awillingness to begin to negotiate a cessation of hostilities, which is accepted by the UnitedStates, Ukraine, NATO, and their allies, ultimately fending off calls for military reprisals fromfactions in Japan and the ROK. Another possibility is that there is a coup against Putin, resulting
in either his disappearance or his delivery to the International Criminal Court (ICC) to stand trial
for war crimes committed in Ukraine. Presumably, in the latter case, the new Russian
leadership’s cooperation with the ICC would be part of a deal to spare other members of theRussian leadership prosecution for similar crimes.114
Variant 2: Reaction
In this variant, either the United States/NATO/Japan do not receive any warning of the launch or
do receive warning but do not believe that the detonation is meant to be mostly a demonstration.
Rather, when the launch is detected, first by Japanese early-warning systems on Hokkaido,command and control systems automatically ready US nuclear-tipped missiles in Alaska, andalert nuclear submarines in the area. With sufficient apparent evidence at hand to conclude,
rightly or wrongly,115 that the Russian launch is meant as the prelude to an attack on military orcivilian targets in the Far East, the US leadership feels obliged, perhaps encouraged by Japan (asin the “Threats to Russian SSBN Bastions” use case, above), to launch a nuclear 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 landbased fleet infrastructure, but most of the submarines and ships normally based there are at sea,
and thus survive the attack. In response, and again as in the earlier use case, Russian submarines
and ships fire conventional and nuclear missiles on other US bases in the region, including navybases and airfields in the ROK.
The evidence that might lead the United States and its allies to conclude that the Russian launch
is a prelude to a broader nuclear attack by Russian forces might include, for example, intercepted
Russian nuclear alert orders, submarine fleet dispersion orders, identified warhead movement(from satellite images or other intelligence), and/or apparent strike orders intercepted to specificnuclear forces, which intelligence analysts with the ear of the US president cite (again, rightly or
wrongly) as evidence of further preparation by Putin of next steps in nuclear escalation if theinformation to the United States or NATO. It must be understood that the authors of this use case are merely
positing this as a condition for restraint by the United States and its allies and have no knowledge of suchinformation conduits one way or another, although such conduits have historical precedents.
114
Note that if a coup resulted in a split in the Russian military, it could precipitate a very dangerous period inwhich the United States and NATO do not know who controls the Russian nuclear launch codes. Such a situation
occurred during the period when a coup was mounted against Soviet President Mikael Gorbachev in 1991. See, forexample, Sara Fritz and John M. Broder (1991), “COLUMN ONE: Nuclear Russian Roulette: The coup plotters briefly
got their hands on Gorbachev’s satchel that controls atomic weapons. And that’s just the start of security worries
in the crumbling Soviet Union,” Los Angeles Times, dated August 31, 1991, and available ashttps://www.latimes.com/archives/la-xpm-1991-08-31-mn-1279-story.html
115
The evidence that might lead the United States and its allies to conclude that the Russian launch as the prelude
to a broader nuclear attack by Russian forces might include, for example, intercepted Russian nuclear alert orders,
submarine fleet dispersion orders, identified warhead movement, and/or apparent strike orders intercepted to
specific nuclear forces.

102

atmospheric nuclear detonation did not have the desired effect of forcing NATO to back off in
Ukraine and/or the western front. Other desired effects of the nuclear detonation, from Putin’s
point of view, might include solidifying the support of Putin’s inner circle of Russian leadershipand flushing out generals who did not agree with Putin and/or other potential traitors who might
mount a coup against his leadership. If the detonation does not (or does not sufficiently)
strengthen Putin’s position at home, Western analysts might conclude that Putin may be readying
further nuclear escalation.
Use Case Consequences
In the “Restraint” variant (1) of this use case, additional detonations of nuclear weapons are
avoided, if only just barely. A period of intense negotiation between Russia and the UnitedStates/NATO/Japan/the ROK ensues, during which Russian economic problems mount, andRussian troops first withdraw to territory held prior to February 2022, and then begin returning
home. While negotiations are going on, opposition groups in Russia grow stronger and become
political forces. As a result, Russian positions in negotiation change as Russian leadershipchanges. Ultimately, agreement is reached that resets Ukraine’s borders back to pre-2014
conditions, specifies the governance of regions of Ukraine previously held by Russia, and sets aschedule for reparations to Ukraine from Russia for the damage caused by the war, paid for inpart by seized and frozen Russian assets (state and private), and in part by funds deducted from
European payments for resumed deliveries of Russian oil and gas, although those deliveries areat a much lower, and decreasing, level than was the case before the conflict in Ukraine. Russia
also agrees to reduce its deployed forces in the NEA region, and to pay reparations to damages
done in the region by the nuclear detonation. In return, a militarily and (likely) economicallydiminished Russia is allowed, in phases and over a probationary period of many years—during
which democratic reforms are monitored by the international community—to rejoin international
institutions. With new leadership in Russia, and with continued support in the United States, newnuclear arms control discussions begin and make progress. With its European oil and gas sales
less lucrative, Russia is drawn back into discussions of trade in forms of renewable energy,
including in NEA.
China, still battling COVID and (in part as a result) showing lower economic growth and startingto hear more domestic voices critical of the regime, focuses inward, refrains from escalating
military confrontations in East Asia, and largely watches the negotiations between the UnitedStates/NATO and others and Russia play out. Although it does not join the new nuclear arms
control discussions, at least in the short term, it does throttle back on building new nuclear
weapons facilities, in part to avoid further international attention and in part to save money fordomestic infrastructure investments.
The DPRK, facing a COVID crisis of its own, also substantially stays out of the conflict. With its
supporters in Russia no longer willing or able to provide backing for a belligerent DPRK, andwith DPRK leadership not relishing the thought of increased dependence on China, the DPRK
uses the opportunity to request and receive a “reset” in its relations with the West, and embracesa slow, phased path toward engagement and threat reduction, including collaboration with theUnited States and with the DPRK’s neighbors in the region on a range of energy and otherinitiatives.
The “Reaction” variant (2) of this use case results in a decidedly different outcome. US attacks
on Russian bases, and resulting Russian counterattacks, bring on exchanges of ICBMs that leave103major areas of the United States, Europe, Russia, and NEA in ruins and the world economy intatters and effectively no longer functioning.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Uncertainties in this use case include:•

Would the United States and its allies be able to avoid escalating a nuclear conflict
following the “demonstration” Russian nuclear detonation, as in Variant 1?

•

Is it really possible that the type of first use described above will have relatively
limited direct impacts?

•

Would China refrain from taking advantage of US engagement with Russia and not,for example, increase pressure on Taiwan?

•

Would Japan and/or the ROK encourage or discourage the United States from
responding to a Russian “demonstration” with nuclear weapons?

•

Is it possible that the end-game of a Ukraine conflict could really unfold as in Variant
1? That is, could Russian governance and international outlook change sufficiently toallow Russia to become once again an acceptable partner in the international
community?

•

Are there ways in which Variant 2 could be stopped short of nearly global nuclear
war?

The ultimate outcomes of the two variants, following the threads above, could be as follows:
In Variant 1, Russian leadership becomes less erratic and provocative. Russia accepts a morecollaborative, less aggressive role in the world order, and gradually is accepted as a more reliable
partner in world affairs. China becomes less assertive with its neighbors and around the world
after seeing what has happened in Russia (and to the Russian economy), and undergoes a gradualchanging of its leadership, with a younger, more West-friendly group of leaders taking over, andgradually working toward offering more in the way of personal liberties for Chinese citizens.
The DPRK is mindful of what has happened in Russia, but also notes that the United States andits partners did exercise restraint in Russia’s case. Facing increasing difficulties with COVID andthe economy at home, the DPRK’s leadership comes back to negotiations, freezes its nuclear
program, and over time, in exchange for economic and security guarantees, takes steps to reduce
the threat posed by its nuclear weapons program.
In Variant 2, absent some restraint on United States/NATO and Russian second strikes, or a
rapid breakthrough in negotiations that seems incompatible with recent leadership trends in
Russia (at least), much of Europe, North America, and NEA would likely be devastated, as wellas possibly Asian locations in Russia where ICBMs are located. Australia, as a US ally, might
not be spared, and whether China could somehow stay out of the conflict is uncertain, and may
depend on whether US warheads land near Chinese territory.
Initial policy lessons from this case include, as in the “Dead Hand Error” case, the importance ofworking to build in opportunities and mechanisms for communications between adversaries
when an aggressive launch is perceived, and, if second strikes are initiated, to limit second
strikes so that nuclear war does not go global.
104

“Conflict from Ukraine Spreads East”
Recognizing that Russia is a nuclear power on both the West and East ends of Eurasia, theUnited States and its Western allies seek to restrain Russia from using nuclear weapons inNortheast Asia. Even though they have not deployed troops to Ukrainian (or Russian orBelarusian) territory, the United States and NATO continue to retain and reinforce substantial
deployments on the Eastern edge of NATO and continue to send arms into Ukraine in sufficientquantities that NATO’s supplies of weapons, and supply lines, are stretched. This leaves theUnited States with little additional manpower or conventional weapons inventory to deploy tocounter rising threats from China, the DPRK, and Russia in Northeast Asia. As a result, and at
the urging of a less DPRK-conciliatory government in the ROK and similar sentiments in Japan,
the US bring more nuclear weapons back into the region, on submarines and ships, and places
more nuclear-capable bombers in the region. This causes Russian nuclear forces in the region to
go to a higher alert status, and ultimately, to attack US military assets with nuclear weapons.
This first use is considered to be toward the “unintentional” end of the spectrum, because it isbased on a miscalculation about the intent of the US and its allies in moving nuclear weapons to
the region.
Triggering Events and First Use
With Russian nuclear forces in the region on high alert, and the Russian military and leadership
feeling the strain of the impact of sanctions on the Russian economy building up within the
Russian people, Russian leadership begins to see an excuse to escalate tensions to what it
believes will be a survivable limited nuclear exchange. Russian leadership's intent is to use
nuclear weapons in order to bolster support at home, but it wants to do so away from the
population centers of western Russia. The excuse comes in the form of the participation of one ormore US warships recently arrived in Northeast Asian waters in large joint US/ROK/Japan
exercises, to be held in the late spring. The US warships are believed (or possible evenannounced) to be carrying nuclear weapons and to be outfitted for advanced anti-submarine
warfare. Russia first states that it believes the exercise to be a prelude (or cover) for an attack on
its nuclear submarine fleet and threatens the use of nuclear weapons if the exercise is notdiscontinued and the participating US warships withdrawn. When the US ships are notwithdrawn, Russia uses nuclear weapons from a patrolling nuclear submarine on a naval base in
the region hosting the ships, likely in Japan,116 and on a flotilla of US and allied vessels at sea.
How the Conflict Evolves
The incoming missile targeting the flotilla of US and allied vessels is detected on launch, and theflotilla begins to scatter before the warhead on the missile is detonated. Although many of thevessels in the flotilla are disabled or sunk, several key vessels with antisubmarine capabilities
survive, and, along with US and allied submarines and aircraft, immediately begin searching for
Russian submarines in the region. In addition, the United States launches a tactical nuclear attack
on a Russian submarine base in the region, destroying the base as well as several surface vessels
and submarines in port at the time.
At this point, US leadership announces to Russia that is targeting key military and leadership
locations in Russia, and also announces that it is invoking Article 5 of the NATO treaty,
116

But probably not in Okinawa, where the US doesn’t have a large naval presence—rather, for example, in
Sasebo, near the southern end of the Japanese archipelago on Kyushu.

105

following the attack on its ships.117 As a result, NATO forces begin to move toward Russia’s
western borders. At that point, however, heeding the pleas of ROK and Japanese leaders to try
and engage in diplomacy before additional nuclear shots are fired, and mindful of China’s
movement to high alert status, the United States and NATO offers Russia an opportunity to avoid
further exchanges of nuclear weapons if it stands its nuclear forces down. Although faced with
war on two fronts and suffering from military attrition caused by the Ukraine war, Russian
leadership initially resists the call to cease hostilities, but, perhaps with the intervention ofcommanders or other personnel directly responsible for using nuclear weapons, does not
immediately fire additional nuclear weapons.
Use Case Consequences
Within days it becomes clear that Russian leadership has erred in assuming that its use of nuclear
weapons would galvanize public support behind it, as massive public rallies in Moscow andother cities in Russia overwhelm security personnel, and Russian leadership goes into hiding aschaos reigns for several days. The United States and its allies watch the situation warily, andwork to directly contact Russian military units in charge of Russia’s nuclear weapons, indicatingthat although nuclear weapons locations in Russia are being targeted by US weapons, the UnitedStates does not intend to fire on those locations absent further provocation from Russia. An
uneasy cessation of hostilities ensues, in which both sides pursue rescue and recovery operationsin the areas that have been attacked.
China closely monitors the situation but makes no military moves. China nervously watches the
movement of fallout from the attack on Okinawa to see if its coastal cities, including Wenzhou
and Taizhou (each about 700 km from Okinawa, and with about 16 million residents betweenthem) will need to be evacuated, although it is unlikely that fallout from that distance will pose aradiological hazard.
Within weeks, it becomes clear that, although there have been no official pronouncements,
Russia’s leadership has essentially abdicated, and as popular protests continue, formerly jailed or
marginalized opposition leaders begin to take power in a process of reorganization of Russian
governance that will ultimately take many months before the overall direction is clear, andlonger before government systems are once again fully stable.
Use Case Uncertainties, Ultimate Outcome, and Policy Lessons
Uncertainties in this use case include:•

Would the United States stop at the destruction of Russian Far East bases andsubmarines?

•

Would Russian nuclear forces hold their fire after the first nuclear exchange?

•

Could a situation such as that outlined above become severe enough to induce Russian
leadership to abdicate? Would key leaders need to be provided with personal security
guarantees in order for an abdication to happen, and if so, would such guarantees be

117

NATO (2022), “Collective defence - Article 5,” last updated: 24 Mar. 2022, and available ashttps://www.nato.int/cps/en/natohq/topics_110496.htm

106palatable to either the Russian people or the international community, particularly
with the alleged war crimes during the Ukraine conflict in mind?
•

As in other cases, would China refrain from taking advantage of US engagement with
Russia and not, for example, increase pressure on Taiwan?

•

Would Japan and/or the ROK encourage or discourage the United States fromlaunching a broader attack on Russia?

The ultimate outcomes of this use case, following the processes set in motion as above, could be
similar to the first variant of the “Sending a message…” case above, with Russian leadership, in
this instance, having changed completely, becoming much more West-friendly, and graduallyaccepted again as a partner in world affairs, although likely not at the same level of importanceas before. Russia and the United States restart nuclear disarmament talks in earnest and makesignificant progress on threat reduction. China also begins to experience turnover in its
leadership, and as in the previous use case, could become more West-friendly. The DPRK, with
Russia no longer likely to be a supporter at the same level as before (including much-reduced
access to military hardware), invites a return to negotiations on its nuclear program, and thosetalks also ultimately result in nuclear threat reduction and the DPRK’s economic opening to theinternational community.
Initial policy lessons from this case include, as in the other cases, the importance of working tobuild in opportunities, channels, and mechanisms for communications at a military-to-militarylevel between adversaries so as to allow the nuclear conflict to be limited. For civilian leaders,remaining open to non-nuclear solutions to a conflict even in moments of crisis are crucial toenabling the avoidance of global nuclear war. And communications throughout both governmentand civil society between nations—in this case, critically, between Russia, the United States, andChina—will be needed to follow and understand what will be an extremely fluid situation if
there is a major upheaval in leadership in Russia or any other nation with a major military.

107

Annex 2: Use Case Elaborations
Augmenting the tables of parameters and summary descriptions provided in section 3 of thisreport, more detailed narrative elaborations of the evolution of each of the five use cases
evaluated are provided below.
“We’re Still Here” Variant 1 (Evaluated Use Case 1):
Notes and References, First Use:
The DPRK first use target is the village of Daejin, but the detonation is centered about 500 m
offshore, meaning significant damage but not over an extensive area. The HOB of the detonation
is designed to limit damage and fallout. The yield (single-stage fission) is at the lower end ofassumptions by H. Kristensen/M. Korda regarding the yield range of most DPRK weapons as of2021.118 The missile used is assumed to be a short-range type that the United States has
designated as KN-23, similar to the Russian Iskander-M missile,119 with an accuracy of 100-200
m.120 The time of attack (early afternoon) is designed to create a spectacle.
Notes and References, First Response Detonations:
The United States response targets for nuclear weapons in this use case are the suspected ballistic
missiles facilities in the Sino-ri area and at Sangnam-ni.121 Yield for US responses is assumed to
be at the upper end of "low yield" in weapons of adjustable yield such as the submarine ballistic
missile warhead W76-2 apparently deployed during the Trump administration.122 Different
sources list various yields for the warheads, including "5 kT," "5-7 kT," and "8 kT." Weprovisionally use the upper end of this range. Time of attack is in the middle of the night toreduce potential for detection and for movement of missiles from sites by DPRK forces.

118

Hans M. Kristensen, Matt Korda (2021), North Korean nuclear weapons, Bulletin of the Atomic Scientists,
Volume 77, 2021 - Issue 4, pages 222-236, published online: 21 Jul 2021, and available ashttps://www.tandfonline.com/doi/full/10.1080/00963402.2021.1940803
119
Missile Defense Advocacy Alliance (2022), “Missile Threat and Proliferation: KN-23,” available ashttps://missiledefenseadvocacy.org/missile-threat-and-proliferation/todays-missile-threat/north-korea/kn-23/120
Michael Elleman (2019), North Korea’s New Short-Range Missiles: A Technical Evaluation, 38 North, dated
October 9, 2019, and available as https://www.38north.org/2019/10/melleman100919/
121
NIKKEI Asia (undated, but probably 2019), “A satellite view of North Korea’s nuclear sites”, available ashttps://asia.nikkei.com/static/vdata/north-korea-nuclear/newsgraphics/north-korea-nuclear/, quoting
CSIS/Beyond Parallel/Digital Globe 2019.
122
See, for example, Alex Wellerstein (2022), “Low-Yield Nukes Are Still Dangerously Destructive,” Outrider, dated
May 25, 2022, and available as https://outrider.org/nuclear-weapons/articles/low-yield-nukes-are-stilldangerously-destructive; Joseph S. Bermudez Jr., Victor Cha and Lisa Collins (2019), “Undeclared North Korea: The
Sangnam-ni Missile Operating Base”, Beyond Parallel, CSIS, dated February 15, 2019, and available ashttps://beyondparallel.csis.org/undeclared-north-korea-sangnam-ni-missile-operating-base/, and William M. Arkin
and Hans M. Kristensen (2020), US Deploys New Low-Yield Nuclear Submarine Warhead, Federation of American
Scientists, dated January 29, 2020, and available as https://fas.org/blogs/security/2020/01/w76-2deployed/

108

“US Leadership Hubris” (Evaluated Use Case 2):
Notes and References, First Use:
The United States targets nuclear weapons and related facilities are the suspected ballistic
missiles facilities in the Sino-ri area and at Sangnam-ni, a suspected enrichment facility at
Kangson, south and west of Pyongyang, and the known enrichment and plutonium production
facilities at Yongbyon.123 In addition, the United States targets a suspected military bunker on theother (Northeast) side of Pyongyang, east of Mt. Taesong, a site described as "[t]his hill has been
turned into the fortress with underground bunkers, AAA and SAM batteries, artillery positions
and even ballistic missile launch site."124 Yield for initial US weapons is assumed to be at theupper end of “low yield," such as the submarine ballistic missile warhead W76-2 apparently
deployed during the Trump administration.125 These targets close to (but not in) Pyongyang areselected by US military planners in part to cause "shock and awe" among DPRK citizens.
Notes and References, First Response Detonations:
Following the US attack, the DPRK is able to get several of its hidden ballistic missiles launchedand points them toward US military targets. Only one gets through (others are shot down by
ROK missile defense systems or fail to function properly), at Camp Humphries in the ROK. At
the same time, infiltration missions are set in motion to launch sea-based clandestine attacks insmall ships using DPRK special forces to attack mixed military-industrial targets in the ROK andJapan. Two of these are successful, one in the Incheon area of the ROK and one in Yokohama,Japan.
Notes and References, Additional Detonations:
Following the DPRK attacks on their territories, the ROK and Japan insist that the US launch a
nuclear attack against the DPRK leadership. Intelligence credible to the US administration places
DPRK leadership either at the Changsuwon Palace near Pyongyang or near Wonsan. Because
leadership has thought to have retreated to a deeply-buried bunker in one of those locations, bothare bombed with B61-12 nuclear bombs with earth-penetrating capability, with yields set at 50
kT.126 Sources suggest the accuracy of this weapon is 30 meters. This attack would presumably
take place by an airstrike, possibly using a B-2 or other type of bomber from Alaska or the US
mainland, once DPRK air power and air defenses were largely neutralized by US/ROK
conventional weapons. The attacks are assumed to be carried out before dawn to reduce risk toaircraft and enhance the probability of targets being in residence.
The attack on Pyongyang, and specifically, on DPRK leadership targets, brings China into thewar, with two successful attacks on Air Force and Marine bases on Okinawa (Kadema AFB andCamp Schwab), and possibly some additional attempted attacks intercepted. China uses 200 kT

123

NIKKEI Asia, ibid.
Wikimapia (2017), “Fortress (Pyongyang),” available as http://wikimapia.org/73770/Fortress.
125
Wellerstein (2022), ibid, and Bermudez et al (2019), ibid.
126
Hans Kristensen, “Video Shows Earth-Penetrating Capability of B61-12 Nuclear Bomb,” Federation of American
Scientists, dated, January 14, 2016, and available as https://fas.org/blogs/security/2016/01/b61-12_earthpenetration/; Airforce Technology (2020), “B61-12 Nuclear Bomb,” dated November 6 2020, and available ashttps://www.airforce-technology.com/projects/b61-12-nuclear-bomb/; and Hans M. Kristensen and Robert S.
Norris (2014), “The B61 family of nuclear bombs,” Bulletin of the Atomic Scientists, 70:3, pages 79-84, available ashttps://www.tandfonline.com/doi/pdf/10.1177/0096340214531546
124

109

warheads launched from submarines or using land-based missiles.127 China also uses ICBMs toattack Joint base Elmendorf Richardson in Alaska,128 which it claims is the origin of the US
nuclear weapons used in the DPRK, and Ellsworth Air Force Base in South Dakota, hoping to
reduce US ability to attack Chinese targets with nuclear bombers, and to try and avoid an
exchange of weapons that might target national leadership. China also attacks the Norfolk Naval
Base in Virginia, however, catching two aircraft carriers in port. China uses ground-based
missiles to hit those targets, with an assumed size of 300 kT. Weapons are launched in the earlymorning hours; those targeting the United States arrive around the middle of the day.
One day after the Chinese attacks on US territory, the United States responds with ICBM attacks
on several sites. Those that succeed are as follows. The first is on the Datong-409 Brigade andDatong Airbase (Lanzhou Airport),129 which is a major missile site and apparently a military (aswell as clearly civilian) airport. There is a major, fairly new uranium enrichment facility at
Lanzhou, but it is 40 km away and probably would not be affected by a strike at the Datong
Airbase unless it were directly targeted. The second is on a reported long-range missile site at
Xuanhua, outside of Beijing.130 The third is near the Southern Theater Command Navy
headquarters in Zhanjiang, Guangdong Province. We assume these attacks use W87 warheads
with yields of 300 kT.131 These warheads are assumed to be launched on ICBMS and arrive atnight.
“Use by Terrorists” Variant 1 (Evaluated Use Case 3):
Notes and References, First Use:A terrorist group obtains a bomb, possibly from the DPRK, but possibly from Russia or anothersource, and brings it in overland and/or by ship/boat to an area near the Tokyo waterfront. In thisexample, a location near the Shinbashi train is the target, and rush-hour timing on a weekday is
chosen for maximum effect. The weapon is brought in by small boat at night to an area a few
hundred meters from the target, then moved on a cart or in a small truck to the target area, where
it is concealed for remote detonation. Nuclear forensic analysis of residual plutonium from thebomb, although not completed for months after the detonation, points to the DPRK, but it is notstrong enough to be unequivocal. The DPRK denies any role in the attack or in providing
weapons for the attack. Responsibility for the attack is claimed by a stateless terrorist group.
The combination of the DPRK's denials, the lack of clear evidence identifying DPRK
proliferation as the source of bomb materials, and the DPRK's offers to assist Japan in recovering
127

See Wikipedia (2023), “China and weapons of mass destruction,” available ashttps://en.wikipedia.org/wiki/China_and_weapons_of_mass_destruction, quoting a 2006 report by Hans M.
Kristensen, Robert S. Norris, and Matthew G. McKinzie.
128
Wikipedia (2023), “Joint Base Elmendorf–Richardson,” available ashttps://en.wikipedia.org/wiki/Joint_Base_Elmendorf%E2%80%93Richardson
129
Cryptome.org (2008), “People's Republic of China Nuclear Weapons Facilities, Eyeball: Vertical Shaft Testing
Facilities, Near Hsin-ko-erh,” reference and photo, dated 28 May 2008, available ashttps://cryptome.org/eyeball/prc-nukes/prc-nukes.htm
130
Atomic Archive (2023), “PRC's Nuclear Facilities“, available ashttps://www.atomicarchive.com/almanac/facilities/prc-facilities.html
131
See, for example, Minutemanmissile,com (undated, but possibly 2011), “Minuteman Missile Nuclear Warheads:
W59 Warhead,” available as https://minutemanmissile.com/nuclearwarheads.html; and Center for Arms Control
and Non-Proliferation (2021, updated January 2023), “Fact Sheet: U.S. Intercontinental Ballistic Missiles,” available
as https://armscontrolcenter.org/fact-sheet-u-s-intercontinental-ballistic-missiles/

110

from the detonation and general pro-engagement attitude following the detonation convince theUnited States not to attempt to punish the DPRK using nuclear weapons.
“Conflict from Ukraine Spreads East” (Evaluated Use Case 4):
Notes and References, First Use:
Deciding that an attack on their bases was imminent, due to changes in US deployment of
nuclear weapons in the region, Russia attacks the US naval base at Sasebo with an RSM-56"Bulava" multiple (in this case, 3)-warhead submarine-launched ballistic missile.132 Thisparticular missile has been the result of an expensive program of recent development, so as aminor consideration in the use case, the use of the RSM-56 may be helpful in domestic politics
for Russia. Russia also attacks a flotilla of US and Japanese ships gathered in the Sea of Japan(as they did in April of 2022133) with a pair of RK-55 Granat (SS-N-21) cruise missiles, also
launched from submarines.134
Notes and References, First Response Detonations:
The United States uses submarine-launched tactical nuclear weapons to attack the Russian
submarine base at Petropavlovsk-Kamchatskiy and two naval bases in Vladivostok.135
Assurances prior to firing keep the Chinese from retaliating, although they are not happy to havenuclear detonations so close to their territory, nor are the DPRK, although the latter also do notrespond militarily.136“Not Going Well in Taiwan” (Evaluated Use Case 5):
Notes and References, First Use:
Before the 2024 election in Taiwan, China attacks the island in September of 2023.137 China
attacks Taiwan's perimeter defenses, but suffers significant setbacks, including the loss of
airfields in Fujian Province and the loss of significant naval ships, when the United States and its
allies, including forces from the ROK and Japan, come to the aid of Taiwan. Considering the US
attacks an attack on China, China decides to use nuclear weapons on US military targets in the132

Also called SS-N-32, see Wikipedia (2023), https://en.wikipedia.org/wiki/RSM-56_Bulava, andhttps://sgp.fas.org/crs/nuke/R45861.pdf
133
See Mari Yamaguchi (2022), “Japan, US Hold Navy Drills Off Koreas Amid Nuke Test Worry,” The Diplomat,
dated
April 13, 2022, and available as https://thediplomat.com/2022/04/japan-us-hold-navy-drills-off-koreas-amid-nuketest-worry/
134
CSIS Missile Threat Project (2021), “RK-55 Granat (SS-N-21),” MissileThreat, dated August 2, 2021, and available
as https://missilethreat.csis.org/missile/ss-n-21/
135
Federation of American Scientists (2000), “Pacific Fleet,” updated September 07, 2000, and available ashttps://nuke.fas.org/guide/russia/agency/mf-pacific.htm
136
See also Wesley Culp (2022), “Russia’s Submarine Fleet In the Pacific Should Make the Navy Sweat”, 1945,
dated May 23, 2022, and available as https://www.19fortyfive.com/2022/05/submarines-russia-pacificexpansion/, and David Scott (2022), “Russian Naval Strategy for the Indo-Pacific”, dated April 14, 2022, andavailable as https://cimsec.org/russian-naval-strategy-for-the-indo-pacific/
137
See, for example Keoni Everington (2022), "US Navy head says China could attack Taiwan before 2024," Taiwan
News, dated October 21, 20223, and available as https://www.taiwannews.com.tw/en/news/4693479

111

region, including the naval base at Sasebo, a base on Okinawa, and bases on Guam, in large partto deter US reinforcements for the conflict around Taiwan.138
Notes and References, First Response Detonations:
The United States determines that some of the weapons used to attack its bases were fired from asite south of Qingzhou,139 and uses submarine-launched nuclear weapons with relatively low
yields to destroy that site and another missile base in Xinyang.140 It uses larger "bunker busting"weapons on the new ICBM sites in western China in an attempt to limit the degree to which
China can retaliate on the US with ICBMs.141 The US also attacks a known nuclear missile basein Tianshui.142
Notes and References, Additional Detonations:
In reprisal for US attacks on its missile facilities, and to reduce US air power in the region, China
attacks the Kunsan and Osan Air Force Bases in the ROK, the latter on the outskirts of Seoul.143"The US responds, somewhat as in ""US Leadership Hubris"", with ICBM attacks on several
sites. Those that succeed in this case are as follows. The first is on the Datong-409 Brigade andDatong Airbase (Lanzhou Airport--reference and photo, which is a major missile site andapparently a military (as well as clearly civilian) airport.144 The second is on a reported (as of2010, anyway145) major nuclear weapons storage site near Taibai, in Shaanxi Province, although
as it is unclear if the exact location of this reportedly deeply buried site is known, the attack is on
the Taibai county town thought to be near the site in the hopes of damaging local infrastructure
sufficiently to make moving weapons out of storage difficult. The third is near the Southern
Theater Command Navy headquarters in Zhanjiang, Guangdong Province. We assume these138

References for Missiles and targets: Hans M. Kristensen and Matt Korda, “Nuclear Notebook: Chinese nuclear
forces, 2021”, Bulletin of the Atomic Scientists, dated November 15, 2021, and available ashttps://thebulletin.org/premium/2021-11/nuclear-notebook-chinese-nuclear-forces-2021/; Brad Lendon (2020),“US Air Force pulls bombers from Guam,” CNN, dated April 24, 2020, and available ashttps://www.cnn.com/2020/04/24/asia/guam-us-air-force-bombers-pull-out-intl-hnk/index.html; and US
Government Accountability Office (2017), “The Evolving U.S. Military Presence on Guam,” dated June 15, 2017,and available as https://www.gao.gov/blog/2017/06/15/the-evolving-u-s-military-presence-on-guam]
139
Hans Kristensen (2020), “China’s New DF-26 Missile Shows Up At Base In Eastern China,” Federation ofAmerican Scientists, dated January 21, 2020, and available as https://fas.org/blogs/security/2020/01/df26deployment/
140
GlobalSecurity.org (undated, but probably 2018), “666 Brigade - DF-26, Xinyang City, Henan Province,
32.168633, 114.125817,” available as https://www.globalsecurity.org/wmd/world/china/xinyang.htm
141
Matt Korda and Hans Kristensen (2021), “China Is Building A Second Nuclear Missile Silo Field,” Federation ofAmerican Scientists, dated July 26, 2021, and available as https://fas.org/blogs/security/2021/07/china-is-buildinga-second-nuclear-missile-silo-field/; and Shannon Bugos and Julia Masterson (2021), “New Chinese Missile Silo
Fields Discovered”, Arms Control Today, dated September 2021, and available ashttps://www.armscontrol.org/act/2021-09/news/new-chinese-missile-silo-fields-discovered
142
Jeffrey Lewis, David Joël La Boon, and Decker Eveleth (2020), “China’s Growing Missile Arsenal and the Risk of a
‘Taiwan Missile Crisis’”, NTI, dated Nov 18, 2020, and available as https://www.nti.org/analysis/articles/chinasgrowing-missile-arsenal-and-the-risk-of-a-taiwan-missile-crisis/
143
East USA.com (undated, but probably 2014), “US military bases in South Korea,” available as https://eastusa.com/us-military-bases-in-south-korea-on-map.html
144
cryptome.org (2008), ibid.
145
Mark A. Stokes (2010), China’s Nuclear Warhead Storage and Handling System, Project 2049, dated March 12,2010, and available as https://project2049.net/wpcontent/uploads/2018/05/chinas_nuclear_warhead_storage_and_handling_system.pdf

112attacks use W87 warheads with yields of 300 kT.146. As in Evaluated Use Case 2, these warheads
are assumed to be launched on ICBMs, and arrive at night.
China's response to the US counterattacks, somewhat as in the "US Leadership Hubris" case,uses ICBMs to attack Joint base Elmendorf Richardson in Alaska,147 which it claims is the originof the US nuclear weapons used in the DPRK, and Ellsworth Air Force Base in South Dakota,
hoping to reduce US ability to attack Chinese targets with nuclear bombers, and to try and avoid
an exchange of weapons that might target national leadership. China also attacks the Norfolk
Naval base in Virginia, however, catching two aircraft carriers in port. China uses ground-based
missiles to hit those targets, with an assumed size of 300 kT. Weapons are launched in the earlymorning hours; those targeting the United States arrive around the middle of the day. China also
attacks the Yokosuka Naval base, south of Tokyo, with a 200 kT weapon. Note that although weare not choosing to model more attacks, these are unlikely to be the last detonations in thisconflict by the US, China, and possibly, ultimately, other participants.

146

Minutemanmissile,com, ibid, and Center for Arms Control and Non-Proliferation (2021, updated January 2023),
ibid.
147
Wikipedia (2023), “Joint Base Elmendorf–Richardson,” available ashttps://en.wikipedia.org/wiki/Joint_Base_Elmendorf%E2%80%93Richardson)113

Annex 3: Additional Results of Use Cases Evaluation
The following presents tables and maps providing detail on results for each of the detonations
included in the use cases described above.

“We’re Still Here” Variant 1 (Use Case 1):
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 1.

Figure A3-1: Use Case 1, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: (firestorm not possible due to overwater detonation)

114

Figure A3-2: Use Case 1, RD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Contour over combination of low-density forests and fields, inrugged terrain, fuels not sufficient for firestorm, rugged (but forest/fields fires probable).

115

Figure A3-3: Use Case 1, RD-2, Potential Ranges of Potential Firestorm and Other Likely
Lethal Impacts.
Firestorm potential assessment: Contour over medium density forest with rugged terrain
probably not sufficient fuel for firestorm (but forest fires probable).

116

Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 1 from Different Impacts All Detonations:

Table A3-1: Estimated Likely Deaths, Use Case 1

117

Nuclear Fallout Simulation Results: Use Case 1

Figure A3-4: Use Case 1, First Use Detonations, Fallout Modelling Results.

Figure A3-5: Use Case 1, All Detonations, Fallout Modelling Results.

118

“US Leadership Hubris,” Use Case 2:
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 2.

Figure A3-6: Use Case 2, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: The >10 cal/cm2 contour is largely over fields and sparseforest with few buildings, thus the overall density of fuel probably is too low to form a firestorm,
although individual fires will destroy forests and residential areas.

119Figure A3-7: Use Case 2, FUD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: The >10 cal/cm2 contour is over medium density forest withrugged terrain and probably does not provide sufficient fuel for firestorm (but forest fires areprobable).

120

Figure A3-8: Use Case 2, FUD-3, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: The >10 cal/cm2 contour is largely over fields, with buildings
in only part of the contour, thus the overall density of fuel probably is too low to form afirestorm, although fires in residential areas will likely be significant.

121

Figure A3-9: Use Case 2, FUD-4, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: The >10 cal/cm2 contour is mostly over fields, medium density
forest, river, with some structures. Probably not enough to sustain firestorms, but special
considerations in terms of emissions from spot fires is required due to nuclear fuel cycle
activities at Yongbyon site.

122

Figure A3-10: Use Case 2, FUD-5, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: The >10 cal/cm2 contour is mostly over fields, with relatively
few buildings, thus the overall density of fuel probably is too low to form a firestorm, althoughfires in residential areas will likely be significant.

123

Figure A3-11: Use Case 2, RD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Mix of buildings and open space, but the overall density offuel is probably too low to form firestorm, although fires in some large buildings (warehouses
and other buildings) will be significant.

124

Figure A3-12: Use Case 2, RD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Firestorm considered possible. Although some of the area
within the >10 cal/cm2 contour is over water, the presence of large fuel tanks, as well as somedense housing, within the contour would seem to make a firestorm quite possible. In addition,
extensive residential areas within the 5-psi zone but outside the firestorm zone would make thepossibility of secondary fires significant.

125Figure A3-13: Use Case 2, AD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Firestorm considered unlikely due to low-density forests, little
built-up areas in ranges of >15 cal/cm2 fluence.

126

Figure A3-14: Use Case 2, AD-2, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Low vegetation in the zone of fluence >15 cal/cm2, few builtup areas, and rugged terrain suggest a firestorm from this detonation is unlikely.

127

Figure A3-15: Use Case 2, AD-3 and AD-4, Ranges of Potential Firestorm and Other Likely
Lethal Impacts.
Firestorm potential assessment: Firestorm considered possible for AD-4 due to inclusion of
built-up areas within much of the contour. In In addition, extensive residential areas nearby may
would make the possibility of secondary fires significant. For AD-3, as much of the area within
the >15 cal/cm2 contour is over water. A firestorm seems unlikely, but many of the separated
built-up areas and forest areas will likely burn.

128

Figure A3-16: Use Case 2, AD-5, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Firestorm considered possible due to inclusion of built-up
areas within much of the contour, although about half of the area is mostly forest or wetlands. In
addition, extensive residential areas nearby may would make the possibility of secondary fires
significant.

129

Figure A3-17: Use Case 2, AD-6, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Low vegetation, much concrete, and relatively few structuresin the zone of fluence >15 cal/cm2 suggest a firestorm from this detonation is unlikely.

130

Figure A3-18: Use Case 2, AD-7, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Although much of the zone of fluence >15 cal/cm2 is overwater, enough contiguous built-up areas are within the contour that a firestorm from thisdetonation appears possible.

131Figure A3-19: Use Case 2, AD-8, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Low vegetation in the zone of fluence >15 cal/cm2, andrelatively little built-up areas, suggest a firestorm from this detonation is unlikely.

132

Figure A3-20: Use Case 2, AD-9, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Although some of the area within the zone of fluence >15
cal/cm2 is over areas of limited vegetation, about one-third of the area is covered relatively
densely with buildings, making a firestorm in that area possible.

133Figure A3-21: Use Case 2, AD-10, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Firestorm possible due to high density of housing and otherbuildings.

134

Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 2 from Different Impacts All Detonations:

Table A3-2: Estimated Likely Deaths, Evaluated Use Case 2*Cumulative with First-Use and Response Detonations

135

Nuclear Fallout Simulation Results: Use Case 2: “US Leadership Hubris”

Figure A3-22: Use Case 2, First Use Detonations, Fallout Modelling Results.

136

Figure A3-23: Use Case 2, First Use and Response Detonations, Fallout Modelling
Results.

Figure A3-24: Use Case 2, All Detonations, Fallout Modelling Results.

137

“Use by Terrorist” V1, Use Case 3:
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 3.

Figure A3-25: Use Case 3, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts.
Firestorm potential assessment: Firestorm possible due to high density of housing and otherbuildings, although presence of some tall buildings may have an unknown effect.

138

Figure A3-26: Use Case 3, FUD-1, Ranges of Potential Firestorm and Other Likely Lethal
Impacts including 0.5 psi impact range (blue circle).

139

Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 3 from Different Impacts.

Table A3-3: Estimated Likely Deaths, Use Case 3

140

Nuclear Fallout Simulation Results: Use Case 3: Nuclear Weapon Use by
Terrorists Variant 1.

Figure A3-27: Use Case 3, Fallout Modelling Results.

141

“Conflict from Ukraine Spreads East”, Use Case 4:
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 4.

Figure A3-28: Use Case 4, FUD-1 through FUD-3, Ranges of Potential Firestorm andOther Likely Lethal Impacts.
Firestorm potential assessment: Firestorm possible due to high density of housing and otherbuildings, although parts within the zones of fluence >15 cal/cm2 are over areas of forests andwater.

142

Figure A3-29: Use Case 4, FUD-4 and FUD-5, Attack on Ships at Sea, Ranges of Likely
Lethal Impacts.
Firestorm potential assessment: No firestorm is possible as attack is over water, but individual
ships will likely be set ablaze.

143

Figure A3-30: Use Case 4, RD-1, Attack on Submarine Base, Range of Potential Firestorm
and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm unlikely due to attack being partially over water,
limited vegetation and structures, but buildings within area will likely be set ablaze.

144

Figure A3-31: Use Case 4, RD-2 and RD-3, Attack on Naval Bases, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorms unlikely because the areas within the zones offluence >10 cal/cm2 are areas with limited buildings and limited vegetation, and much of each of
the potential firestorm zones are over water.

145

Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in Use
Case 4 from Different Impacts, All Detonations.

Table A3-4: Estimated Likely Deaths, Use Case 4146

Nuclear Fallout Simulation Results: Use Case 4: “Conflict from Ukraine Spreads
East.”

Figure A3-32: Use Case 4, Fallout Modelling Results.

147

“Not Going Well in Taiwan”, Use Case 5:
Maps of impact contours for prompt radiation, thermal fluence, overpressure, andfirestorm, Use Case 5.

Figure A3-33: Use Case 5, FUD-1 and FUD-5, Attack on Naval Bases, Japan, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm possible due to high density of housing and otherbuildings, although parts within the zones of fluence >15 cal/cm2 are over areas of forests andwater.

148

Figure A3-34: Use Case 5, FUD-2 and FUD-3, Attack on Naval Bases, Guam, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm unlikely due to housing and other structures on only
a portion of the zones of fluence >15 cal/cm2, with some of the rest being water and low forest,
though local fires and forest fires will likely occur.

149

Figure A3-35: Use Case 5, FUD-4, Attack on Military Base, Okinawa, Japan, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm possible due to high density of housing and otherbuildings, although parts within the zones of fluence >15 cal/cm2 are over areas of forests,
tarmac, and water.

150

Figure A3-36: Use Case 5, RD-1, Attack on Missile Site, China, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm unlikely due to housing and other structures on onlya small portion of the zones of fluence >10 cal/cm2, with much of the rest being sparsevegetation.

151

Figure A3-37: Use Case 5, RD-2 through RD-5, Attack on Missile Sites, China, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorms unlikely for these sites due to lack of buildings andvegetation.

152

Figure A3-38: Use Case 5, RD-6, Attack on Missile Site, China, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm possible for this site, although site has some open
areas of vegetation that may not provide much fuel.

153

Figure A3-39: Use Case 5, RD-7 through RD-10, Attack on Missile Sites, China, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorms unlikely for these sites due to lack of buildings andvegetation.

154

Figure A3-40: Use Case 5, AD-1, Attack on Military Base, ROK, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorms probably not likely for this site due to most of thearea of 15 cal/cm2 fluence being agricultural fields, tarmac, solar panels, and golf courses.

155

Figure A3-41: Use Case 5, AD-2, Attack on Military Base, ROK, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm is possible for this site due to large built-up areas
and dense housing in the southern and eastern part of the contour.

156

Figure A3-42: Use Case 5, AD-3, Attack on Missile Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm is unlikely for this site due to lack of vegetation overmuch of the site, large areas of tarmac, and limited built-up areas within the 15 cal/cm2 fluence
contour.

157

Figure A3-43: Use Case 5, AD-4, Attack on Missile Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm is unlikely for this site due to relatively sparse forest
vegetation over much of the area within the 15 cal/cm2 fluence contour and the rugged
topography of the region, but serious fires likely over the built-up areas near ground zero and in
the forests in the surrounding area.

158

Figure A3-44: Use Case 5, AD-5, Attack on Naval Base, China, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm likely over at least part of this site (western built-up
area within the 15 cal/cm2 fluence contour. Other built-up areas, separated from this built-up area
by water, would also likely burn in separate fires.

159

Figure A3-45: Use Case 5, AD-6, Attack on Military Base, United States (Alaska), Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm likely over at least a large part of this site within the
15 cal/cm2 fluence contour. The northern part of the area likely has insufficient fuel to support afirestorm.

160

Figure A3-46: Use Case 5, AD-7, Attack on Military Base, United States, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm unlikely due to low vegetation (agricultural fields)
and few structures over the 15 cal/cm2 fluence contour.

161

Figure A3-47: Use Case 5, AD-8, Attack on Military Base, United States, Range ofPotential Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm likely in built-up area in the southern part of the 15
cal/cm2 fluence contour, although much of the fluence contour is over water.

162

Figure A3-48: Use Case 5, AD-9, Attack on Military Base, Japan, Range of Potential
Firestorm and Other Likely Lethal Impacts.
Firestorm potential assessment: Firestorm likely in built-up area over most of the 15 cal/cm2
fluence contour, although the eastern portion of the fluence contour is mostly over water.

163

Summary of Estimated Overall Likely Deaths and Eventual Cancer Deaths in
Evaluated Use Case 5 from Different Impacts, All Detonations.

Table A3-5: Estimated Likely Deaths, Use Case 5164

Nuclear Fallout Simulation Results: Use Case 5: “Not Going Well in Taiwan.”

Figure A3-49: Use Case 5, First Use Detonations, Fallout Modelling Results.

165

Figure A3-50: Use Case 5, First Use and Response Detonations, Fallout Modelling
Results.

Figure A3-51: Use Case 5, All Detonations, Fallout Modelling Results.
166