The US military is structured under the Department of Defense, comprising six armed forces—Army, Navy, Air Force, Marine Corps, Space Force, and Coast Guard. It operates via a dual-chain of command: administrative (organizing/training) and operational (combatant commands).
The President of the United States serves as Commander-in-Chief, with command flowing to the Secretary of Defense and Joint Chiefs of Staff.
The key structural components include the Department of the Army, Department of the Navy, Department of the Air Force, and Department of Homeland Security, which operates the Coast Guard under the Navy during war.
The operational chain of command is as follows: The President ➔ Secretary of Defense ➔ Unified Combatant Commands (regional or functional commanders).
The administrative chain of command is: The President ➔ Secretary of Defense ➔ Secretaries of the Military Departments ➔ Service Chiefs ➔ Units.
Each branch has active duty and reserve components, with a structure hierarchy organized from small to large: Squads, Platoons, Companies, Battalions, Brigades, Divisions, and Corps.
