Joint Chiefs of Staff Special Historical Study: A Historical Study of Strategic Connectivity, 1950-1981 [open pdf - 4MB]
"The term strategic connectivity has entered the lexicon of military usage only recently. The Joint Chiefs of Staff have defined it as: the facilities, systems, and procedures that interconnect the National Command Authorities (NCA), National Military Command System (NMCS), nuclear CINCS [Commander-in-Chief Reporting System], and nuclear executing commanders. It encompasses the NCA, Military Staff Office in the White House, the White House Communications Agency (WHCA), National Military Command Center (NMCC), Alternate National Military Command Center (ANMCC), NORAD [North American Aerospace Defense Control] warning systems, National Emergency Airborne Command Post (NEACP), CROWN Helicopter operations (USMC [U.S. Marine Corps] helicopters used to move the President], and all links and nodes that interconnect these facilities with the executing commanders of SIOP [Single Integrated Operational Plan] aircraft, Intercontinental Ballistic Missile (ICBM) Launch Control Centers (LCCs), and Ballistic Missile Submarines (SSBNs). Although the term is recent, the procedures and systems that compose strategic connectivity are not. Ever since the deployment of nuclear weapons with US military forces, it has been essential to have assured control and connection between those forces and the proper command authorities. Systems and procedures to that end have evolved over the years in accordance with the constantly expanding technology associated with nuclear weapons and the means for their delivery."
National Security Archive at George Washington University: http://www.gwu.edu/~nsarchiv/