The governing concept infnsing US nuclear strategy over the past two decades has been mutual assnred destruction (MAD). This concept postulates that once the United States and the Soviet Union achieved an invulnerable second-strike capabi Ii ty, stabi Ii ty would result. By definition the doctrine required that each side be able to offer a genuine threat to the other in the form of an invulnerable second-strike capability. Thns, if either side's second-strike capability became vulnerable it would be necessary to reestablish an invulnerable retaliatory force.
Thornton, Richard C. and Lewis, William H.
"Arms Control and Heavy Missiles,"
Naval War College Review: Vol. 37
, Article 9.
Available at: http://digital-commons.usnwc.edu/nwc-review/vol37/iss1/9