Characteristics of Successful U.S. Military Interventions Jennifer Kavanagh, Bryan Frederick, Alexandra Stark, Nathan Chandler, Meagan L. Smith, Matthew Povlock, Lynn E. Davis, Edward Geist C O R P O R A T I O N For more information on this publication, visit www.rand.org/t/RR3062 Library of Congress Cataloging-in-Publication Data is available for this publication. ISBN: 978-1-9774-0227-1 Published by the RAND Corporation, Santa Monica, Calif. © Copyright 2019 RAND Corporation R® is a registered trademark. Cover: Image via H&B Photography/Fotolia. Limited Print and Electronic Distribution Rights This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited. Permission is given to duplicate this document for personal use only, as long as it is unaltered and complete. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial use. For information on reprint and linking permissions, please visit www.rand.org/pubs/permissions. The RAND Corporation is a research organization that develops solutions to public policy challenges to help make communities throughout the world safer and more secure, healthier and more prosperous. RAND is nonprofit, nonpartisan, and committed to the public interest. RAND’s publications do not necessarily reflect the opinions of its research clients and sponsors. Support RAND Make a tax-deductible charitable contribution at www.rand.org/giving/contribute www.rand.org Preface This report documents research and analysis conducted as part of a project entitled Characteristics of Successful Military Interventions, sponsored by the Office of the Deputy Chief of Staff, G-3/5/7, U.S. Army. The purpose of the project was to inform U.S. Army strategic planning and the decisions of defense leadership by identifying the characteristics of the most effective and efficient U.S. military interventions and the operating environments in which different types of military interventions are most likely to succeed. The Project Unique Identification Code for the project that produced this document is HQD177567. This research was conducted within RAND Arroyo Center’s Strategy, Doctrine, and Resources Program. RAND Arroyo Center, part of the RAND Corporation, is a federally funded research and development center (FFRDC) sponsored by the United States Army. RAND operates under a “Federal-Wide Assurance” (FWA00003425) and complies with the Code of Federal Regulations for the Protection of Human Subjects Under United States Law (45 CFR 46), also known as “the Common Rule,” as well as with the implementation guidance set forth in U.S. Department of Defense (DoD) Instruction 3216.02. As applicable, this compliance includes reviews and approvals by RAND’s Institutional Review Board (the Human Subjects Protection Committee) and by the U.S. Army. The views of sources utilized in this study are solely their own and do not represent the official policy or position of DoD or the U.S. government. iii Contents Preface ................................................................................................. iii Figures and Tables ...................................................................................vii Summary .............................................................................................. xi Acknowledgments ................................................................................ xxiii Abbreviations ....................................................................................... xxv CHAPTER ONE Introduction ........................................................................................... 1 Objective of This Report .............................................................................. 1 Research Approach ..................................................................................... 2 Contributions and Limitations of This Report ..................................................... 3 Report Organization ................................................................................... 4 CHAPTER TWO Existing Literature: Findings and Shortcomings ............................................... 7 Data Sets That Include Political Objectives ........................................................ 8 Factors That Affect Intervention Outcomes and Success ........................................10 Limitations of Existing Research ................................................................... 23 CHAPTER THREE Collecting Data on U.S. Military Interventions .............................................. 27 Learning from Previous Interventions ............................................................. 27 U.S. Military Interventions ......................................................................... 27 Intervention Political Objectives ....................................................................33 Degree of Success in Achieving Political Objectives ............................................. 42 Using the Data ........................................................................................49 CHAPTER FOUR Factors That Affect Success: A Quantitative Look ............................................53 Research Approach ....................................................................................53 Results ................................................................................................. 60 v vi Characteristics of Successful U.S. Military Interventions CHAPTER FIVE Factors That Affect Success: Case Studies ......................................................75 Case Selection .........................................................................................75 Factors That Affect Success ..........................................................................79 Summary: Factors That Matter .................................................................... 99 CHAPTER SIX Synthesis and Recommendations ............................................................... 103 Key Determinants of Success ...................................................................... 103 Recommendations .................................................................................. 107 Areas for Future Research .......................................................................... 112 APPENDIXES A. Codebook: Data Collection and Definitions ............................................ 115 B. Case Studies.................................................................................... 131 C. Statistical Analyses ........................................................................... 271 D. List of Cases .................................................................................... 303 References ........................................................................................... 309 Figures and Tables Figures S.1. Ongoing U.S. Military Interventions by Region, 1898–2016 .....................xiii S.2. Categorization of Political Objectives in U.S. Military Interventions ............ xiv S.3. Percentage of Political Objectives Successfully Achieved, by Historical Period ......................................................................................xv 3.1. Ongoing U.S. Military Interventions, 1898–2016 ...................................31 3.2. Ongoing U.S. Military Interventions by Region, 1898–2016 ......................31 3.3. U.S. Military Interventions by Activity Type ........................................32 3.4. U.S. Military Interventions Involving Forces from Ground, Air, and Sea Domains ..................................................................................32 3.5. U.S. Military Interventions by Size of Ground, Air, and Naval Components ...33 3.6. Categorization of Political Objectives in U.S. Military Interventions .............39 3.7. Political Objectives in U.S. Military Interventions by Historical Period ........ 40 3.8. Percentage of Political Objectives Successfully Achieved, by Historical Period ......................................................................................45 3.9. Successful Achievement of Political Objectives by Category and Time Period ..................................................................................... 46 3.10. Degree of Success in Achieving Political Objectives by Region ....................47 3.11. Degree of Success in Achieving Political Objectives by Primary Activity Type ...................................................................................... 48 3.12. Degree of Success in Achieving Political Objectives by Size of Intervention .... 50 B.1. Number of U.S. Forces in Korea, 1945–1949 ...................................... 132 B.2. Estimated Number of U.S. Forces in Japan, 1945–1989 .......................... 154 B.3. U.S. Economic Assistance to Japan, 1946–1952 ................................... 162 B.4. Pace of Repatriation of Japanese and Non-Japanese Nationals, 1945–1948 .... 165 B.5. Japanese Exports, 1946–1960 ........................................................ 169 B.6. Japanese Gross National Product, 1940–1960 ..................................... 169 vii viii Characteristics of Successful U.S. Military Interventions Tables S.1. Typology for Categorizing the Political Objectives of U.S. Military Interventions ............................................................................ xiv S.2.