The purpose of this book is to introduce readers to INDOPACOM, which is responsible for U.S. military operations in a region covering approximately 50 percent of the Earth from the Pacific Ocean to the Indian Ocean. INDOPACOM has not received much attention in Japan compared to USFJ or the US Seventh Fleet. This book shines a spotlight on INDOPACOM in an effort to promote an understanding of its various aspects. The mission of INDOPACOM is to protect U.S. territory, people, and national interests. However, it also includes protection of the countries within its geographic scope that are U.S. allies and security partners. INDOPACOM and its precursor Pacific Command, established in 1947, have always been major contributors to the peace and safety of Japan in the post-World War II era. In view of the importance of U.S. interests in Northeast Asia, the region also has two Sub-Unified Combatant Commands called United States Forces Japan (USFJ) and United States Forces Korea (USFK). Each of these organizations strives to strengthen the relationship with the Japan Self-Defense Forces and the Republic of Korea armed forces. Together, the United States, Japan and our partners around the globe will continue to safeguard the rules-based security order that has underpinned peace and prosperity for decades.