The U.S. Strategic Command last year held one of its largest major exercises simulating a nuclear attack on the United States and a counterstrike involving bombers, ground-based missiles and submarine-launched missiles. Air Force Gen. Kevin Chilton last week told the House Armed Services subcommittee that the exercise was “the most extensive nuclear command, control and communications field exercise in over a decade.” “It demonstrated the full range of nuclear deterrence capabilities by integrating submarine strategic deterrent patrols, more than 90 aircraft sorties, an ICBM test launch, and five days of continuous airborne command-and-control operations,” he said. The exercise, held from...