According to the Washington Post, the United States Strategic Command contingency plan for dealing with "imminent" threats from countries such as North Korea or Iran is formally known as CONPLAN 8022-02. The plan was reportedly completed in November 2003, resulting in a preemptive and offensive strike capability. The main plan involves the preemptive use of tactical nuclear strikes (mini-nukes) on deep-ground rocket/bomb installations, computer viruses, and radar disruption technology.
See: Single Integrated Operational Plan for origins and details.
References
CONPLAN 8022-02 Wikipedia(Text) CC BY-SA