The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, which advises the president of the United States, the secretary of defense, the Homeland Security Council and the National Security Council on military matters.

Trump's own nominee for the position is currently retired Air Force lieutenant general Dan Caine.

This first-of-its-kind firing of a chairman[10] has been seen by some in the press as "part of a campaign led by [Trump's] defense secretary to rid the military of leaders who support diversity and equity in the ranks.

"[11] This motive was also viewed in Hegseth's simultaneous firing of the first woman to serve on the JCS, Admiral Lisa Franchetti, former chief of naval operations, on the same day.

After the 1986 reorganization of the Armed Forces undertaken by the Goldwater–Nichols Act, the Joint Chiefs of Staff does not possess operational authority over troops or other units.

Today, their primary responsibility is to ensure personnel readiness, policy, planning and training of their respective services for the combatant commanders to utilize.

The Army and Navy were unsupportive of each other at either the planning or operational level and were constrained by disagreements during the Spanish–American War in the Caribbean campaigns.

The Joint Board also lacked the ability to originate its own opinions and was thus limited to commenting only on the problems submitted to it by the secretaries of war and Navy.

As a result, the Joint Board had little to no impact on the manner in which the United States conducted World War I.

U.S. president Franklin D. Roosevelt and British prime minister Winston Churchill established the Combined Chiefs of Staff (CCS) during the 1942 Arcadia Conference.

The UK portion of the CCS would be composed of the British Chiefs of Staff Committee, but the United States had no equivalent body.

Modeled on the British Chiefs of Staff Committee, the JCS' first formal meeting was held on February 9, 1942, to coordinate operations between War and Navy Departments.

By the end of the war each had been promoted: Leahy and King to fleet admiral; Marshall and Arnold to general of the Army.

The JSSC, "one of the most influential planning agencies in the wartime armed forces", was an extraordinary JCS committee that existed from 1942 until 1947.

[24] Members included Lieutenant General Stanley D. Embick, U.S. Army, chairman, 1942–1946, Vice Admiral Russell Willson, U.S. Navy, 1942–1945, Vice Admiral Theodore Stark Wilkinson, U.S. Navy, 1946, and Major General Muir S. Fairchild, U.S. Army Air Force, 1942–?.

With the end of World War II, the Joint Chiefs of Staff was officially established under the National Security Act of 1947.

The law was amended during the term of General Louis H. Wilson, Jr. (1975–79), making the commandant a full-time JCS member in parity with the other three DoD services.

Brown Jr., chairman of the Joint Chiefs of Staff, on November 3, 2023, replacing SEAC Ramón Colón-López.

The Joint Staff (JS)[36][37] is a military headquarters staff based at The Pentagon (with offices in Hampton Roads, Virginia; Fort Leavenworth, Kansas; Lackland Air Force Base, Texas; Fort Belvoir, Virginia; Fairchild Air Force Base, Washington and Fort McNair, District of Columbia) composed of personnel from all the six armed services, assisting the chairman and the vice chairman in discharging their responsibilities.

The chairman of the Joint Chiefs of Staff (CJCS) is assisted by the director of the Joint Staff (DJS), a three-star officer who assists the chairman with the management of the Joint Staff, an organization composed of approximately equal numbers of officers contributed by the Army, the Navy and Marine Corps, the Air Force, the Space Force, and the Coast Guard, who have been assigned to assist the chairman in providing to the secretary of defense unified strategic direction, operation, and integration of the combatant land, naval, space, and air forces.

[42] The Joint Staff includes the following departments where all the planning, policies, intelligence, manpower, communications and logistics functions are translated into action.

[43] The Joint Staff includes the following departments where all the planning, policies, intelligence, manpower, communications and logistics functions are translated into action.

§ 154(a)(1) respectively, which use the collective term "armed forces" rather than listing the eligible services, as well as to other positions on the Joint Staff.