The U.S.-Japan Alliance and Deterring Gray Zone Coercion in the Maritime, Cyber, and Space DomainsScott W. Harold, Yoshiaki Nakagawa, Junichi Fukuda, John A. Davis, Keiko Kono, Dean Cheng, Kazuto SuzukiC O R P O R A T I O N iii Preface To understand the importance of the U.S.-Japan alliance against the backdrop of a rapidly changing international environment in the Asia-Pacific, RAND convened a conference in early 2017 focused on the use of gray zone coercion in the maritime, cyber, and space domains. The conference brought together leading U.S. and Japanese experts to unearth areas of shared understanding and divergence in thinking on the two sides of the Pacific when it comes to dealing with Chinese efforts to reshape the international order through coercion designed to fall below the level that would invoke a treaty response under the U.S.-Japan alliance. The conference found numerous opportunities for the allies to collaborate in improving shared understandings, reducing ambiguities that China can exploit, stigmatizing gray zone coercion, hardening defenses, and preparing to impose costs. Although it will not be easy to deter gray zone coercion in the maritime, cyber, and space domains, the allies face strong incentives to improve their coordination and strengthen deterrence now, before China or other actors change the status quo at the expense of Washington and Tokyo. This work was sponsored by the Government of Japan and conducted in the International Security and Defense Policy Center (ISDP) of the RAND National Security Research Division (NSRD). ISDP analyzes changes in the international political, strategic, economic, and technological environment and helps the Department of Defense and other clients develop policies to shape the environment and advance U.S. and allied interests. For more information on the RAND International Security and Defense Policy Center, see www.rand.org/nsrd/ndri/centers/isdp or contact the director (contact information is provided on the webpage). Contents Preface . iiiFigures and Tables . viiFigures . viiTables . viiAbbreviations . viii1. Introduction . 1Chapter Summaries .42. Using Land Forces to Deter Maritime Gray Zone Coercion: The Role of the Japan Ground Self-Defense Forces in the Nansei (Ryukyu) Islands . 11Background .12The Strategic Importance of the Nansei Islands .14The Japanese Imperial Army in the Pacific Theater in World War II .15Controlling the Sea from the Shore: The JGSDFs New Surface-to-Air and Antiship Cruise Missile Capabilities .16The Threat to Japans Nansei Islands .17The Posture of the JGSDF in the Nansei Island Chain .17The Limitations of the Japan Ground Self-Defense Forces .18The U.S.-Japan Alliance: An Indispensable Partnership for Peace .21Conclusion .213. A Japanese Perspective on the Role of the U.S.-Japan Alliance in Deterringor, If Necessary, DefeatingMaritime Gray Zone Coercion . 23Examples of Chinas Gray Zone Tactics in the Maritime Domain .24Chinas Gray Zone