i ABOUT UNIDIR UNIDIR is a voluntarily funded, autonomous institute within the United Nations. One of the few policy institutes worldwide focusing on disarmament, UNIDIR generates knowledge and promotes dialogue and action on disarmament and security. Based in Geneva, UNIDIR assists the international community to develop the practical, innovative ideas needed to find solutions to critical security problems. NOTE The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in the publication are the sole responsibility of the individual authors. They do not necessary reflect the views or opinions of the United Nations, UNIDIR, its staff members or sponsors. www.unidir.org © UNIDIR 2020 ii iii iv TABLE OF CONTENTS Foreword ......................................................................................................................... 1 Executive Summary ....................................................................................................... 3 Chapter One. Nuclear Risk Reduction: Closing Pathways to Use ............................ 5 WILFRED WAN Introduction ................................................................................................................ 7 Challenges to Moving Forward .................................................................................. 9 A Framework for Analysis ......................................................................................... 11 Risk Reduction in Context ........................................................................................ 13 Chapter Two. Nuclear Risk Reduction: A Framework for Analysis (Reprinted) .. 16 WILFRED WAN Context ...................................................................................................................... 17 Outline ....................................................................................................................... 18 Nuclear Weapon Use Scenarios ............................................................................... 19 Doctrinal Use ................................................................................................................................... 20 Escalatory Use ................................................................................................................................. 22 Unauthorized Use .......................................................................................................................... 24 Accidental Use ................................................................................................................................ 27 Interactive Effects .......................................................................................................................... 28 Addressing Use Scenarios ........................................................................................ 31 Reducing Doctrinal Risk .............................................................................................................. 32 Reducing Escalatory Risk ............................................................................................................ 34 Reducing Unauthorized Risk ..................................................................................................... 38 Reducing Accidental Risk ........................................................................................................... 41 Risk Reduction in Practice ........................................................................................ 45 Moving Forward ........................................................................................................ 48 Appendix ................................................................................................................... 50 v Chapter Three. Multipolarity, Great Power Competition, and Nuclear Risk Reduction ..................................................................................................................... 52 ANKIT PANDA Summary ................................................................................................................... 53 Introduction .............................................................................................................. 54 The Evaporation of Arms Control ............................................................................. 55 Perception, Misperception, and Great Power Doctrinal Risk ................................... 57 Great Power Competition and Emerging Capabilities ............................................. 59 Escalation Risks ......................................................................................................... 62 South Asia ......................................................................................................................................... 62 Northeast Asia ................................................................................................................................ 64 Other Regional Escalation Risks ............................................................................................... 65 Risk Reduction Recommendations ........................................................................... 66 Chapter Four. Nuclear Risk and the Technological Domain: A Three-Step Approach ....................................................................................................................... 70 JOHN BORRIE Summary ................................................................................................................... 71 Introduction .............................................................................................................. 72 Increasing Strategic Concerns .................................................................................. 74 Which Technologies? ................................................................................................ 77 Anti-Ballistic Missile Defences .................................................................................................. 78 Hypersonic and Other Advanced, Longer-Range Weapons ......................................... 78 Anti-Satellite Weapons ................................................................................................................ 80 Cyber .................................................................................................................................................. 81 Artificial Intelligence, Machine Learning and Autonomy ............................................... 82 Lower-Yield Nuclear Weapons ................................................................................................. 83 Narrowing Technological Pathways ......................................................................... 85 Conclusion ................................................................................................................. 91 Chapter Five. Nuclear Risk in the Euro-Atlantic ...................................................... 94 ULRICH KÜHN Summary ................................................................................................................... 95 Introduction .............................................................................................................. 96 The Euro-Atlantic Region: Complex and Volatile ..................................................... 97 Complexity at Three Levels ........................................................................................................ 97 Political Volatility ........................................................................................................................... 98 vi Manipulating and Perceiving Risk .......................................................................... 100 Risk Asymmetries ........................................................................................................................ 100 (Unofficial) Doctrines ................................................................................................................. 102 Poor Risk Analysis ....................................................................................................................... 103 Cooperatively Addressing Risk ............................................................................... 107 Conclusion ............................................................................................................... 110 Chapter Six. Narrowing Nuclear Use Pathways in Northeast Asia ...................... 112 TANYA OGILVIE-WHITE Summary ................................................................................................................. 113 Introduction ............................................................................................................ 114 Nuclear Use Pathways ............................................................................................ 115 Doctrinal Pathway ...................................................................................................................... 118 Escalatory Pathway .................................................................................................................... 123 Unauthorized Pathway ............................................................................................................