National Command Authority (NCA) is a term used by the United States military and government to refer to the ultimate lawful source of military orders. The term refers collectively to the President of the United States (as commander-in-chief) and the United States Secretary of Defense. 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 a matter of minutes. Detailed Continuity of Operations Plans provided for monitoring the whereabouts of certain key government officials who would become the National Command Authority if the President was killed in an enemy attack. Only the NCA can order the use of nuclear weapons, including the Single Integrated Operational Plan (SIOP). They are also the only command that can deploy F-117s. Neither individual, by himself, can order that strategic nuclear weapons be used. If the NCA determines that a nuclear strike is necessary, they must jointly inform the Chairman of the Joint Chiefs of Staff, who in turn will direct a general officer on duty in the National Military Command Center (NMCC) at the The Pentagon to execute the SIOP. The term refers to communications with those officers in military command to order U.S. forces into action (see Unified Combatant Command).
