Combatant Commands

The armed services recruit, train, and equip forces, but they do not command them in combat. That job belongs to the combatant commands, unified commands made up of forces from more than one service and led by a four-star general or admiral. The system dates to the Second World War and the National Security Act of 1947, and the Goldwater-Nichols Act of 1986 set the modern chain of command, which runs from the President to the Secretary of Defense directly to the combatant commanders. The Joint Chiefs of Staff advise but are not in the chain of command.

There are eleven commands, defined in a classified Unified Command Plan that the President approves. Seven are geographic: Northern Command, covering North America and homeland defense, Southern Command for Latin America, European Command, Africa Command, Central Command for the Middle East and Central Asia, Indo-Pacific Command, and Space Command. Four are functional: Special Operations Command, Strategic Command for nuclear forces, Transportation Command for moving troops and supplies, and Cyber Command.

Combatant commanders are among the most powerful officials in national security, often acting as the senior American presence in their regions. The command structure is periodically reorganized: Space Command was re-established in 2019, and in 2025 the administration proposed consolidating some commands and announced moving Space Command's headquarters to Alabama, decisions debated for their effects on readiness, alliances, and politics.