Updated September 11, 2026 (IF10542)

Congress has exercised oversight and a measure of control over the U.S. military, including by, inter alia, legislating the chain of command, directing changes to military components and their responsibilities, and determining resources for the military.

Military operations, in peacetime and in war, are inherently complex. One key to success, therefore, is a clear, unified chain of command. This enables senior U.S. government leaders—in particular, the President, the civilian Secretary of Defense, and the civilian Service Secretaries—to command and control military forces around the world. (The Secretary of Defense is using "Secretary of War" as a "secondary title" under Executive Order 14347 dated September 5, 2025).

Constitutional Authorities

The U.S. Constitution specifies roles and authorities of the legislative and executive branches related to civilian control, and ultimate command, of military forces.

Article I, Section 8, Clauses 11-14 of the Constitution state, [The Congress shall have Power…] To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years; To provide and maintain a Navy; To make Rules for the Government and Regulation of the land and naval Forces.

Article II, Section 2, Clause 1 states, The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States.

The Chain of Command

Servicemembers are permanently assigned to military departments (e.g., Department of the Army), which are responsible for organizing, training and equipping forces and providing them to combatant commands (COCOMs, e.g., U.S. Central Command), which are responsible for conducting operations. COCOM here refers to a military command with broad, continuing missions and forces from multiple services (i.e., joint forces).

Title 10 §162 U.S.C. specifies that the chain of command for military forces in operations runs from the President, to the Secretary of Defense, to military COCOM Commanders. The military Chairman of the Joint Chiefs of Staff (CJCS) may act as an intermediary, transmitting orders between the Secretary of Defense and the military COCOM Commanders. Each COCOM Commander is a four-star general or flag officer (GFO), appointed by the President and confirmed by the Senate.

Section 162 also specifies that forces not assigned to COCOMs "remain assigned to the military department concerned for carrying out the responsibilities of the Secretary of the military department concerned." This portion of the Armed Forces, also called the "institutional force," is manned, trained, and equipped for assignment to the COCOMs as needed. These forces' chain of command runs from the President, to the Secretary of Defense to the Service Secretaries—Army, Navy, and Air Force. The departments also have military service chiefs, four-star GFOs who assist the Secretaries. Service Secretaries and Chiefs are appointed by the President and confirmed by the Senate.

Unified Command Plan (UCP)

Congress has required the CJCS to "review the missions, responsibilities (including geographic boundaries), and force structure" of each COCOM biannually. The UCP is a classified executive branch document that articulates how the Department of Defense (DOD, which is "using a secondary Department of War designation," under Executive Order 14347 dated September 5, 2025) assigns missions, responsibilities, and forces to the COCOMs (see Figure 1). DOD is to notify and brief Congress on significant revisions. Congress is not included in this review but may influence UCP development through legislation, report language, and oversight.

Figure 1. Combatant Commanders' Areas of Responsibility

Source: Adapted from Association of the U.S. Army, "The Army on Point: A Detailed Summary of Current Operations and Responsibilities (2022)," https://www.ausa.org/publications/army-point-detailed-summary-current-operations-and-responsibilities-2022. Edited by CRS to reflect DOD changes described in the "Developments in Command and Control" section.

Employment of Military Forces

The Services and their respective staffs interact with Congress on statutory and strategic issues that control and undergird worldwide military operations. Service responsibilities include formal budget creation, recruiting, individual and unit training exercises, support to civil authorities, and acquisition program management, including combat capability requirements.

COCOMs are the principal entities through which DOD commands and controls global operations, by employing assigned service units (i.e., forces of a single military service) simultaneously in joint operations. The COCOMs' joint operational capability needs (e.g., communications) can drive the development of military requirements and equipment across DOD. COCOMs' military operations may include overseas high intensity combat operations, humanitarian assistance operations, and homeland defense, as well as defense support to civil authorities within the United States.

Service Component Commands

Service component commands are forces that belong to a particular military service but are assigned to a COCOM. Therefore, they are subordinate to their respective Combatant Commanders. As an example, U.S. Naval Forces Central Command is one of several service component commands assigned to U.S. Central Command (CENTCOM).

Developments in Command and Control

Congress generally delegates to DOD decisions about COCOM missions, responsibility, and force structure. Nevertheless, Congress has exercised its authority over the military in specific cases. For example, Congress established Special Operations Command and Cyber Command with unique legal authorities and capabilities. The National Defense Authorization Acts of FY2016, FY2017, and FY2018 contain provisions, pursuant to congressional defense committees' 2015 hearings, that enhanced the service chiefs' strategic advisory role in managing capability development, resourcing, and force modernization. In the FY2023 NDAA (P.L. 117-263 §1087), Congress directed the Secretary of Defense to establish a joint force headquarters within the U.S. Indo-Pacific Command area of operations. In some cases, Congress has limited funds for withdrawing equipment or troops below a certain level in a given COCOM.

The executive branch has exercised its authority to adjust COCOM responsibilities. DOD incorporated Israel into the CENTCOM Area of Responsibility (AOR) in September 2021 and incorporated Greenland into the U.S. Northern Command AOR in June 2025. In conjunction with the COCOM reorganizations, the U.S. Army has created a Western Hemisphere Command, with a four-star commander, based at Fort Bragg, NC. The command is to be the "Army Service Component Command to U.S. Northern Command and U.S. Southern Command." It is also to include Army Forces in the United States under the Secretary of the Army's control.

An Abbreviated History of the Chain of Command

The means by which the United States controls and commands its forces is a result, in part, of an inherent tension between preserving civilian control of the military and providing operational freedom to uniformed leaders. The experience of World War II convinced President Truman, among others, of the need to increase coordination and integration (or "jointness") among the military services. Yet there was also concern that integrating the services might result in an overly powerful military that could threaten the principle of civilian control of U.S. forces.

The resulting compromise produced the Joint Chiefs of Staff (JCS), which serves as an advisory body to the President, is comprised of all the military service chiefs, and is headed by a Chairman (CJCS). As a corporate body, the JCS was specifically designed not to exercise command; the CJCS was also to have (and has) no command authority. Nevertheless, the JCS had responsibility for establishing "unified combatant commands." While service chiefs had no command authority, they were assigned executive and administrative responsibilities for these combatant commands. Therefore, they were able to influence ongoing military operations. By 1953, the authority to establish COCOMs was assigned to the Secretary of Defense, although some ambiguity remained a feature of DOD operations and chain of command until 1986.

Military operational failures during several incidents in the early 1980s contributed to perceived shortcomings in the U.S. chain of command. The military services, in the view of some observers, failed to effectively plan or conduct operations jointly due to confusion over whether the military services or unified combatant commanders were ultimately in charge of operations. These incidents included Operation Eagle Claw in Iran (1980) and the Marines deployment to Beirut, Lebanon, in 1983. Congress passed the Goldwater-Nichols Department of Defense Reorganization Act of 1986 (Goldwater-Nichols Act, P.L. 99-433), which mandated clarifications to the chain of command and set the current command and control scheme.

Considerations for Congress

At the time of publication, the Army and Navy have acting secretaries and the Army Vice Chief of Staff is performing the duties of the Army Chief of Staff. These and other changes in leadership since the January 2025 change of administration could affect execution of national security and defense strategies in pursuit of U.S. national interests. Congress may consider changes to DOD statutory authorities and resourcing, deriving from the leadership changes, and whether or not they align with Congress's perspectives on "government and regulation of the land and naval forces."

CRS has identified no publicly accessible means for Congress to directly track funding outlays to COCOMs to aid oversight of COCOM operations. Such expenditures typically flow through the military departments to service components of the COCOMs, which perform tasks directed from COCOM level. Congress may consider establishing methods to aid its oversight of discrete COCOM costs, ranging from combat to peacetime military engagement and training.

The SASC-reported version of an FY2027 NDAA (S. 4784) would establish a new Robotic and Autonomous Systems Command. The bill also would establish five geographic COCOMs, mirroring the current COCOM structure. If passed, these provisions could affect reported UCP update plans.