The person who runs the Pentagon day to day is the Secretary of Defense, a civilian appointed by the President and confirmed by the Senate. Above the Secretary sits the President, who serves as Commander-in-Chief and holds ultimate authority over the entire armed forces. Below them runs a layered structure of civilian officials, senior military advisors, and operational commanders, all built on one principle: the military answers to elected civilian leaders, not the other way around.
The President Sits at the Top
Article II, Section 2 of the Constitution makes the President Commander-in-Chief of the armed forces.1Congress.gov. Article II Section 2 Every major policy direction, strategic priority, and military decision inside the Pentagon flows from that authority. The President appoints the Secretary of Defense, nominates senior military leaders, and sets the national security strategy the building follows.
The operational chain of command runs from the President through the Secretary of Defense straight to the combatant commanders who lead forces around the world.2Office of the Law Revision Counsel. 10 USC 162 – Combatant Commands Assigned Forces and Chain of Command The President is also the only person who can authorize the use of nuclear weapons. Advisors provide recommendations during a crisis, but the final decision belongs to the President alone.3Department of Defense. Nuclear Matters Handbook – Nuclear Weapons Employment Policy, Planning and NC3
Congress placed one significant check on this authority. Under the War Powers Resolution of 1973, the President must notify Congress within 48 hours of committing armed forces to hostilities and generally cannot sustain that deployment beyond 60 days without congressional authorization or a formal declaration of war.
The Secretary of Defense Runs the Department
The Secretary of Defense is the Pentagon’s principal leader and the President’s chief advisor on defense matters. Federal law makes this a civilian position, appointed by the President and confirmed by the Senate.4Office of the Law Revision Counsel. 10 USC 113 – Secretary of Defense The Secretary exercises authority, direction, and control over the entire Department of Defense, which received roughly $893 billion through normal congressional appropriations in fiscal year 2026.
To reinforce civilian control, the law imposes a cooling-off period before any former military officer can hold the job. Officers below the rank of brigadier general must wait at least seven years after leaving active duty; generals and admirals must wait at least ten.4Office of the Law Revision Counsel. 10 USC 113 – Secretary of Defense Congress can waive that rule by passing specific legislation and has done so three times in the department’s history. Every military branch, defense agency, and combatant command ultimately answers to the Secretary.
The Deputy Secretary Keeps the Building Running
The Deputy Secretary of Defense functions as the Pentagon’s chief operating officer. If the Secretary dies, resigns, or is otherwise unable to serve, the Deputy steps in with the full authority of the office.5Office of the Law Revision Counsel. 10 US Code 132 – Deputy Secretary of Defense Day to day, the Deputy focuses on internal management: budget execution, business processes, and administrative operations across one of the largest organizations in the world. That frees the Secretary to concentrate on policy, strategy, and outside relationships with Congress, allied nations, and the White House.
The Joint Chiefs Advise But Do Not Command
The Joint Chiefs of Staff are the Pentagon’s top military advisors. They do not command troops in the field. The Chairman holds the title of principal military advisor to the President, the National Security Council, and the Secretary of Defense.6Office of the Law Revision Counsel. 10 USC 151 – Joint Chiefs of Staff Composition and Functions Despite being the nation’s highest-ranking military officer, the Chairman sits outside the operational chain of command. That distinction, established by the Goldwater-Nichols Act of 1986, was deliberate. It keeps the advice flowing to civilian leaders independent from the pressures of commanding forces.
The Chairman’s statutory duties include helping the President and Secretary with strategic direction, developing contingency plans, advising on how to allocate forces among combatant commands, and reviewing whether each military department’s budget aligns with defense priorities.7Office of the Law Revision Counsel. 10 USC 153 – Chairman Functions The Vice Chairman, the second-highest-ranking officer, oversees joint military requirements and represents the military in National Security Council deputies meetings.8U.S. Department of War. Vice Chairman of the Joint Chiefs of Staff
The full body includes the Chief of Staff of the Army, the Chief of Naval Operations, the Chief of Staff of the Air Force, the Commandant of the Marine Corps, the Chief of Space Operations, and the Chief of the National Guard Bureau.6Office of the Law Revision Counsel. 10 USC 151 – Joint Chiefs of Staff Composition and Functions They meet in a secure conference room known as “the Tank” to hammer out unified military advice. When civilian leaders accept or reject that advice, the Joint Chiefs carry out the decision either way.
Combatant Commanders Direct Operations
The people who actually direct military operations are the combatant commanders. The Department of Defense has 11 combatant commands, each led by a four-star general or admiral.9U.S. Department of War. Combatant Commands Seven cover geographic regions of the world. Four are functional and operate worldwide across regional lines, handling missions like cyber operations, special operations, strategic deterrence, and transportation.
This structure creates an important split. Deployed troops answer to the combatant commander for their region or function, not to the chief of their home branch. The service chiefs recruit, train, and equip forces; the combatant commanders employ them. That separation, another product of the Goldwater-Nichols reforms, was designed to prevent inter-service rivalries from hampering operations.
The Service Secretaries Build the Force
Each military department has its own civilian leader who reports to the Secretary of Defense. The Secretary of the Army runs the Department of the Army.10Office of the Law Revision Counsel. 10 USC 7013 – Secretary of the Army The Secretary of the Navy oversees both the Navy and the Marine Corps.11Office of the Law Revision Counsel. 10 US Code 8013 – Secretary of the Navy The Secretary of the Air Force oversees the Air Force and the Space Force.
These officials handle everything needed to build and sustain a ready force: recruiting, organizing, training, equipping, and managing personnel. They control their department’s budget, set administrative policies, and advocate for their branch inside the Pentagon. What they do not do is command forces in combat. That authority belongs to the combatant commanders. Service Secretaries prepare the force; combatant commanders decide how to use it.
Defense Agencies and Senior Civilian Staff
Beyond the military departments, a group of 28 organizations known as the “Fourth Estate” provides specialized support that cuts across the whole department, including intelligence, logistics, missile defense, research, finance, and health care.12Department of Defense. Defense Agencies and DoD Field Activities Organization Nine of the defense agencies carry a special designation as combat support agencies, which gives the Chairman of the Joint Chiefs oversight of their readiness to support military operations.
These organizations report to the Deputy Secretary of Defense or to one of the Under Secretaries of Defense, depending on their mission. The Under Secretaries handle the policy and administrative work sitting between the Secretary’s strategic decisions and the uniformed military’s operations, covering areas like intelligence and security, policy, personnel, acquisition, and finance.
Congress Controls the Money
Congress does not run the Pentagon, but no dollar gets spent there without its approval. Each year the House and Senate Armed Services Committees review the President’s defense budget request, hold hearings with senior leaders, and produce the National Defense Authorization Act.13Congress.gov. Defense Primer – The NDAA Process The NDAA sets defense policy, authorizes spending levels, and addresses organizational matters. It does not actually provide the money. A separate defense appropriations bill does that.
The two-step process gives Congress real leverage. Authorization can reshape priorities, create or eliminate programs, and impose policy restrictions. Appropriations control how much money actually flows. The annual cycle forces Pentagon leadership to justify its plans before elected officials every year, and Congress can use the process to require changes the military’s own leadership might resist. That is civilian control operating through the legislative branch, running alongside the President’s authority at the top of the chain.