U.S. Indo-Pacific Command (INDOPACOM)

Overview

U.S. Indo-Pacific Command (USINDOPACOM or INDOPACOM) is one of six Department of Defense (DOD) geographic unified combatant commands. The commander of INDOPACOM exercises authority over military forces assigned to the command's area of responsibility (AOR), which includes the Pacific Ocean and about half of the Indian Ocean, as well as countries along their coastlines. INDOPACOM is headquartered outside of Honolulu, Hawaii, and approximately 375,000 military and civilian personnel are assigned to its AOR. Congress may consider whether DOD's budget, posture, and regional strategy supports U.S. national security interests in the Indo-Pacific. For additional background, see CRS Report R47589, U.S. Defense Infrastructure in the Indo-Pacific: Background and Issues for Congress, and CRS Report R47643, Guam: Defense Infrastructure and Readiness.

Mission, Posture, and Organization

DOD has often referred to the INDOPACOM AOR as the department's "priority theater." The 2022 National Defense Strategy states "the most comprehensive and serious challenge to U.S. national security is [China]'s coercive and increasingly aggressive endeavor to refashion the Indo-Pacific region and the international system." DOD has also identified regional threats from Russia and North Korea.

As of September 2023, most of the active-duty U.S. servicemembers assigned to locations in the INDOPACOM AOR were based in Japan (53,246), Hawaii (44,545), South Korea (24,159), and Guam (6,363). DOD operates or has access to over 40 military sites in the region. U.S. forces based at these sites comprise ground units (including the Army's 2^nd Infantry Division and the Marine Corps' III Marine Expeditionary Force), naval warships (including an aircraft carrier, destroyers, cruisers, and amphibious assault ships), and aircraft (including rotary-wing, fighter, electronic attack, bomber, airlift, and tanker units).

INDOPACOM is commanded by a four-star general or flag officer. To date, all commanders have been Navy admirals; the current commander is Admiral John Aquilino. INDOPACOM encompasses five subordinate service component commands (U.S. Army Pacific, U.S. Pacific Fleet, U.S. Marine Forces Pacific, U.S. Pacific Air Forces, and U.S. Space Forces Pacific) and three subordinate unified commands (U.S. Forces Japan, U.S. Forces Korea, and Special Operations Command Pacific). INDOPACOM routinely participates in multinational exercises and other security cooperation activities with regional partners.

Focal Points in the INDOPACOM AOR

INDOPACOM plans for contingencies throughout the AOR. The following hotspots could for various reasons implicate U.S. national security and military forces.

Taiwan. The People's Republic of China (PRC) claims sovereignty over self-ruled Taiwan and has long vowed to unify with it, by force if necessary. The 1979 Taiwan Relations Act (TRA; P.L. 96-8; 22 U.S.C. §3301) states that it is U.S. policy "to maintain the capacity" to "resist any resort to force or other forms of coercion that would jeopardize" Taiwan's security. The TRA does not require the United States to use that capacity to defend Taiwan, but DOD identifies a potential conflict in the Taiwan Strait as "the pacing scenario" for which it is preparing. As such, DOD is "modernizing [its] capabilities, updating U.S. force posture, and developing new operational concepts," alongside long-standing U.S. efforts to bolster Taiwan's defensive capabilities in accordance with the TRA. Among recent actions taken by Congress to support Taiwan's defense are several provisions of the Taiwan Enhanced Resilience Act (Title LV, Subtitle A of the James M. Inhofe National Defense Authorization Act for Fiscal Year 2023; P.L. 117-263).

Korean Peninsula. The threat from North Korea has served as the raison d'être for the U.S.-South Korea alliance since 1953, when the two countries signed a Mutual Defense Treaty at the end of the Korean War. As North Korea continues to advance its ballistic missile and nuclear weapons programs, the United States faces a number of challenges: enhancing alliance preparedness to respond to North Korean aggression without triggering a military conflict; reinforcing the credibility of U.S. extended deterrence; and preparing for the eventual transfer of wartime operational control of alliance forces from a U.S. commander to a South Korean commander. Some analysts have suggested North Korea may be emboldened by its improving military capabilities, and its seemingly close relations with China (and particularly Russia since Moscow's 2022 invasion of Ukraine) to engage in military provocations against United States or South Korea.

South China Sea. Multiple Asian governments claim sovereignty over islands and other geographic features in the South China Sea, one of the world's most heavily trafficked waterways. The PRC, which claims most of the sea, has conducted land reclamation (island-building), constructed military facilities on natural and artificial maritime outposts, and used coercive tactics to impede the activities of other countries, including the Philippines, a mutual defense treaty ally. Successive U.S. Administrations have accused the PRC of deploying its military vessels and aircraft in an unsafe and unprofessional manner against U.S. and other militaries operating in the South China Sea.

Figure 1. The U.S. INDOPACOM AOR and Selected U.S. Bases

Source: CRS Report R47589, U.S. Defense Infrastructure in the Indo-Pacific: Background and Issues for Congress. Notes: AFB is Air Force Base; JB is Joint Base; MCAS is Marine Corps Air Station; MCB is Marine Corps Base; NB is Naval Base; and USAG is U.S. Army Garrison.

East China Sea. The PRC, Japan, and Taiwan all claim sovereignty over the Senkaku Islands in the East China Sea. Since 2010, PRC-Japan tensions over the dispute have simmered as the PRC's maritime forces have increased their operations near the islands, which Japan controls. It has been U.S. policy since 1972 that the Senkakus are covered under Article 5 of the U.S.-Japan Security Treaty, which states that the United States commits to "meet the common danger" of an armed attack on "the territories under the Administration of Japan." Okinawa, which is part of the same island chain, is home to more than half of the 54,000 U.S. troops based in Japan. Japan has bolstered its military presence on the southwestern-most of the Okinawan islands—around 60 nautical miles from Taiwan—as tensions with China have grown.

Issues for Congress

Resourcing INDOPACOM. Congress may assess whether DOD funding requests align with national interests. DOD requested $9.1 billion for the Pacific Deterrence Initiative (PDI) in its FY2024 budget. PDI does not cover the totality of departmental resources required to sustain INDOPACOM operations and the pursuit of regional strategic objectives. Congress may, therefore, assess the strategic alignment of INDOPACOM funding more holistically, to include basing, personnel, and equipment needs alongside common services and support provided by defense agencies and field activities.

Posturing INDOPACOM for Great Power Competition. Since the early 2010s, DOD has increasingly come to identify competition with the PRC as the organizing principle of Indo-Pacific posture. As part of this strategic shift, the U.S. military has increased the number of personnel stationed in the region, secured access to new bases (especially in Australia and the Philippines), and developed new operational concepts that emphasize wider and more diversified combat and logistical operations (i.e., the Army's Multi-Domain Operations, the Air Force's Agile Combat Employment, the Navy's Distributed Maritime Operations, and the Marine Corps' Expeditionary Advanced Basing Operations). Despite this, some argue that INDOPACOM is not adequately prepared for the challenges of a great power war. Congress may consider whether or not to change INDOPACOM's posture—for example, by requiring DOD to assign additional forces and capabilities to the region, or directing INDOPACOM to review the regional infrastructure needs of the services' new operational concepts—to enhance its ability to deter and, if necessary, defeat the PRC.

Force Protection. Much of the INDOPACOM AOR is within range of the PRC's conventional ballistic and cruise missile arsenal (some locations are vulnerable to North Korean and Russian missiles as well). As a result, U.S. bases, personnel, and weapons systems may be at risk of attack in the event of a regional conflict. Congress may assess the degree to which INDOPACOM's existing air and missile defense architecture affords protection from these threats, and consider whether or not to make additional appropriations, enact legislation, or conduct oversight activities aimed at strengthening these capabilities.