National Command Authority
National Command Authority (NCA) is a term used by the Department of Defense of the United States of America to refer to the ultimate lawful source of military orders. The NCA comprises the President of the United States (as commander-in-chief) and the Secretary of Defense (as the deputy to the commander-in-chief) jointly, or their duly deputized successors, i.e. the Vice President and the Deputy Secretary of Defense. The term also refers to communications with the commanding officers of the Unified Combatant Commands to put U.S. forces into action.
The NCA consists only of the President and the Secretary of Defense or their duly deputized alternates or successors. The chain of command runs from the President to the Secretary of Defense (SecDef) and through the Joint Chiefs of Staff to the Commanders of the Unified and Specified Commands. The channel of communication for execution of the Single Integrated Operational Plan (SIOP) and other time-sensitive operations shall be from the NCA through the Chairman of the Joint Chiefs of Staff, representing the Joint Chiefs of Staff, to the executing commanders.— Section 3.1, Department of Defense Directive Number 5100.30 December 2, 1971
After the 1986 reorganization of the United States military undertaken by the Goldwater-Nichols Act, the Joint Chiefs of Staff do not have operational command of US military forces. Responsibility for conducting military operations goes from the President to the Secretary of Defense directly to the commanders of the Unified Combatant Commands and thus bypasses the Joint Chiefs of Staff completely.
The use of the term dates from the Cold War, when the United States and Soviet Union both had nuclear missiles on constant alert, and a responsible official had to be available to authorize a retaliatory strike within minutes. Detailed Continuity of Operations Plans provided for monitoring the whereabouts of certain key government officials who would assume the National Command Authority if the President and/or Secretary of Defense were killed in an enemy attack.
Only the President can direct the use of nuclear weapons, including the Single Integrated Operational Plan (SIOP). While the President does have unilateral authority as commander-in-chief to order that nuclear weapons be used for any reason at any time, the actual procedures and technical systems in place for authorizing the execution of a launch order requires a secondary confirmation under a two-man rule, as the President's order is subject to secondary confirmation by the Secretary of Defense. If the Secretary of Defense does not concur, then the President may in his sole discretion fire the Secretary. The Deputy Secretary of Defense would then assume the office of Acting Secretary of Defense in accordance with the Secretarial order of succession. An Acting Secretary would, likely, face the same test: to countersign the Presidential order or be relieved from office. This potential cycling of Acting Secretaries of Defense could be reminiscent of the so-called "Saturday Night Massacre" at the Department of Justice in 1973. However, the Vice President and a majority of the heads of the Executive Departments could invoke section 4 of the Twenty-fifth amendment to the Constitution and have the President declared incapacitated. The Vice President would then become Acting President until the President submits a declaration to the Speaker of the House and the President pro tempore of the Senate that affirms his ability to discharge his duties.
Once the NCA has authorized a launch order under the proper procedures, the Chairman of the Joint Chiefs of Staff or the Vice Chairman of the Joint Chiefs of Staff, will in turn direct a general officer on duty in the National Military Command Center (NMCC) at The Pentagon to execute the SIOP.