THE UNIVERSITY OF CHICAGO CONVENTIONAL TRIPWIRE DETERRENCE A DISSERTATION SUBMITTED TO THE FACULTY OF THE DIVISION OF THE SOCIAL SCIENCES IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF POLITICAL SCIENCE BY MATTHEW C. SLACK CHICAGO, ILLINOIS DECEMBER 2018 The views expressed in this dissertation are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States government. ii Table of Contents List of tables vi List of figures vii Abstract viii Acknowledgements ix CHAPTER 1: INTRODUCTION 1 1.1 Overview 1 1.2 Literature Review 3 1.3 Dissertation Structure 21 CHAPTER 2: THEORY 22 2.1 Introduction 22 2.2 Assumptions 23 2.3 The Logic of Conventional Tripwire Deterrence 24 2.4 Defender Force Posture Strategies 36 2.5 Attacker Strategies 44 2.6 Conclusion 51 CHAPTER 3: RESEARCH DESIGN 52 3.1 Scope Conditions and Universe of Cases 53 3.2 Case Selection 56 3.3 Methodology 62 3.4 Measurement 67 CHAPTER 4: CHAD 72 iii 4.1 Introduction 72 4.2 Background 77 4.3 Operation Tacaud, 1978-1980 80 4.4 French Withdrawal and Libyan Victory, 1980-1982 90 4.5 Operation Manta – the Red Line in the Desert, 1983-1984 102 4.6 “Mutual” Withdraw, 1984-1985 119 4.7 Operation Epervier – the Airborne Tripwire, 1986-1987 122 4.8 Alternative Explanations 137 4.9 Conclusion 144 CHAPTER 5: CYPRUS 146 5.1 Introduction 146 5.2 Background 147 5.3 Force Posture and Relative Power 151 5.4 Initial Aggressor Strategy – Conventional War 155 5.5 Defender Response 159 5.6 The Second Offensive 169 5.7 British Response 173 5.7 Conclusion 178 CHAPTER 6: TAIWAN 180 6.1 Introduction 180 6.2 1950: Neutralizing the Taiwan Strait 187 6.3 1954-1955 Crisis and Mobile Tripwires 203 6.4 1958: Blockade and Convoys 218 iv 6.5 Conclusion 228 CHAPTER 7: CONCLUSION 231 7.1 Summary of Findings 232 7.2 Policy Implications 237 7.3 Future Research 250 BIBLIOGRAPHY 252 v List of Tables Table 1.1 - Summary of Tripwires in Nuclear and Conventional Deterrence 20 Table 2.1 - Criticisms of Audience Costs, Verbal vs. Tripwire 32 Table 2.2 - Capacity to Escalate Requirements 36 Table 2.3 - Attacker Strategies 50 Table 3.1 - Universe of Tripwires in Extended Immediate Deterrence 55 Table 3.2 - Selected Case Summary 62 Table 3.3 - Defender Force Posture Coding Summary 69 Table 4.1 - Chad Subcase Identification 74 Table 4.2 - Chad Local Balance of Forces Summary 139 Table 4.3 - Overt French Interventions in Sub-Saharan Africa 143 Table 6.1 - Taiwan Subcase identification 182 vi List of Figures Figure 2.1 - 2x2 of Independent variables and predicted outcome 27 Figure 2.2 - Defender Force Posture Strategies 38 Figure 2.3 - Attacker Strategy Selection Process 51 Figure 3.1 - Case Selection 2x2 59 Figure 4.1 - France:Libya Adjusted NMC Ratio 75 Figure 4.2 - Map of Chad 80 Figure 4.3 - Operation Tacaud Forward French Locations 86 Figure 4.4 - Final Manta Force Disposition, May 1984 115 Figure 4.5 - French Financial Flows to Chad 141 Figure 5.1 - Map of Cyprus – Operation Attila I 157 Figure 6.1 - US China Adjusted NMC Ratio 186 Figure 6.2 - Map of US Tripwire, 1954 207 Figure 7.1 - Baltic Geography 240 vii Abstract This dissertation develops a theory to explain the conditions under which a tripwire force posture deters conventional war. Tripwires have been a common policy tool since the Second World War but the literature largely overlooks the nonnuclear potential of tripwires and underestimates the political power of a tripwire despite their relatively low upfront sunk cost. The theory predicts that a small tripwire of military forces deployed to a threatened protégé state ties the hands of the defender state to honor its commitment to the protégé. The tripwire operates via a nationalism mechanism that is universal in the international system and mutually understood by all states. This intelligible signal is credible when paired with the defender’s capacity to escalate by projecting second echelon forces to the protégé’s territory after the outbreak of conventional war. The presence of a tripwire and the capacity to escalate constrains resolved attacker states from selecting a strategy of conventional war by denying its ultimate territorial aims with the impending arrival of second echelon forces. However, the tripwire does not limit the selection of less effective revisionist strategies below the threshold of conventional war. Thus, while tripwires lower the probability of territorial revision by deterring conventional war, motivated attackers still pursue their territorial aims by employing violent and nonviolent strategies that do not ‘trip the wire.’ viii Acknowledgements My time at the University of Chicago has been equally enlightening and humbling and I am exceptionally fortunate to have had the support of the many remarkable people who made this dissertation possible. First, thank you to the members of my committee, Professors Bob Pape, Austin Carson, and John Mearsheimer. Their collective guidance in seminars, lectures, office calls, and on this dissertation has indelibly shaped how I think about the world and approach challenging problems. Special thanks to Bob Pape who as my advisor welcomed me before I ever arrived and made sure I never lost track of the final target. Bob provided countless hours of guidance and advice from orientation, to exams, through a myriad of ideas and papers, all the way to dissertation defense. Thank you to my fellow graduate students in the political science department who presented brilliant ideas and regularly challenged my assumptions. I am especially thankful for the international relations scholars in our cohort, Alexandra Chinchilla, Andrea Bartoletti, Maura Cremin, and my graduate school wingman Lieutenant Colonel Sean Morrow. Thank you for the study sessions, critiques of arguments and papers, and your collective patience in explaining an untold number of concepts. Thank you to the Air Force for the opportunity to study with such incredible people. I am indebted to the Air Force mentors who encouraged me to apply and gave me the opportunity to do so. My gratitude to the friends who reached out over the years sharing encouragement and stories from the ‘pointy end of the spear.’ The conversations were regular reminders of the stakes of sound strategic thinking and of the people who constitute the remarkable Air Force ix community. Finally, thank you to the Air Force Chief of Staff PhD program for the opportunity to immerse in a world of independent and rigorous thought that would have otherwise not been possible. Most importantly thank you to my family. To my wife, who has patiently listened to more monologues on tripwires and obscure historical accounts than one could ever consider reasonable. Thank you for your love, support, and laughter throughout this adventure - I look forward to the next. Thank you to our wonderful daughters who have brought such unbridled joy to life and taught me how to write on ever decreasing amounts of sleep. Finally, thank you to my parents whose unwavering support has granted me every opportunity in life. They are the examples I aspire to be. I hope to repay the debts of those who have expended such effort by striving to uphold the security and safety of the Nation. This dissertation is dedicated to those who have lost their lives at home and abroad working to do the same. Matthew C. Slack x Chapter 1: Introduction 1.1 Overview Deterring aggression and promoting stability with the forward stationing of military forces has been a mainstay of American foreign policy since the end of the Second World War.1 The policy continues today as the 2015 and 2017 United States National Security Strategies emphasize US interest in deterring interstate aggression and preserving regional stability. The strategies both state that US forces will deter aggression through forward presence and engagement. Should deterrence fail, the United States will project power to defeat or deny revisionist action.2 Efforts to prevent aggression are not the sole domain of the United States and many other major and regional powers have sought to deter potential aggressors from territorial aggression against protégé states. Forward deploying combat forces is a common defender strategy in such extended deterrence scenarios to signal the defender’s commitment to the protégé and to bolster the protégé’s defenses.3 This dissertation investigates a unique defender deployment strategy: the tripwire. A tripwire is a small military combat force that lacks the mass 1 Tim Kane, “Global US Troop Deployment, 1950-2003,” Heritage Foundation (2004). Retrieved from: http://www.heritage.org/defense/report/global-us-troop-deployment-1950-2003. For contrasting views on the value of forward troops in supporting US grand strategy, see Stephen G. Brooks and G. John Ikenberry and William C. Wohlforth. "Don't Come Home, America: The Case against Retrenchment." International Security 37, no. 3 (2012): 7-51; and Barry Posen, Restraint a New Foundation for US Grand Strategy (Ithaca: Cornell University Press, 2014); 2 United States National Security Strategy, 2015, 8. Retrieved from: https://obamawhitehouse.archives.gov/sites/default/files/docs/2015_national_security_strategy_2.pdf; and United States National Security Strategy, 2017, 47. 3 Common examples are the US military deployment to Western Europe throughout the Cold War, the US deployment to South Korea since 1950, or today’s US Army deployment to the Baltics and Eastern Europe. On the ongoing US deployment to Eastern Europe as a demonstration of US commitment, see: http://www.eur.army.mil/AtlanticResolve/; “Operation Atlantic Resolve Fact Sheet,” US Army-Europe.