"The number of people connecting to the Internet is growing at an astounding rate: estimates range from 100% to 400% annually over the next five years. This unprecedented level of interconnectedness has brought with it the specter of a new threat: cyberterrorism. This thesis examines the impact of this threat on the critical infrastructure of the United States, specifically focusing on Department of Defense issues and the National Information Infrastructure (NII). A working definition for cyberterrorism is derived, and a description of the Nation's critical infrastructure is provided. A number of possible measures for countering the threat of cyberterrorism are discussed, with particular attention given to the concept of information assurance. Information assurance demands that trustworthy systems be developed from untrustworthy components within power-generation systems, banking, transportation, emergency services, and telecommunications. The importance of vulnerability testing (or red-teaming) is emphasized as part of the concept of information assurance. To support this, a cyberterrorist red team was formed to participate in the Marine Corps' Urban Warrior Experiment. The objective of this thesis is to address the impact of these issues from a Systems Management perspective. This includes taking into account the changes that must occur in order to improve the U.S.' ability to detect, protect against, contain, neutralize, mitigate the effects of, and recover from attacks on the Nation's Critical Infrastructure."