By 1972, constraints placed on ballistic missiles by the SALT I
treaty prompted U.S. nuclear strategists to think again about using
cruise missiles. There was also concern over Soviet advances in
antiship cruise missile technology, and in Vietnam remotely piloted
vehicles had demonstrated considerable reliability in gathering
intelligence information over previously inaccessible, highly defended
areas. Improvements in electronics—in particular, microcircuits,
solid-state memory, and computer processing—presented inexpensive,
lightweight, and highly reliable methods of solving the persistent
problems of guidance and control. Perhaps most important, terrain
contour mapping, or Tercom, techniques, derived from the earlier Atran, offered excellent...
