National Security Decision Directive 281: United States Nuclear Weapons Command and Control [open pdf - 872KB]
Alternate Title: NSDD 281: United States Nuclear Weapons Command and Control
National Security Decision Directive 281 provides "the basis for the attainment and maintenance of an assured, fully integrated, flexible, secure, responsive, and enduring nuclear command and control system (NCCS) that will provide [the President] in [his] role as Commander in Chief, with all capabilities required to exercise [his] authority and direction over nuclear weapon operations of military forces and all government activities and multinational activities that support those operations."
National Security Decision Directive 281; NSDD 281
Digital National Security Archive: http://nsarchive.chadwyck.com/