"Critical infrastructure includes systems, facilities, and assets so vital that if destroyed or incapacitated would disrupt the security, economy, health, safety, or welfare of the public. Critical infrastructure may cross political boundaries and may be built (such as structures, energy, water, transportation, and communications systems); natural (such as surface or groundwater resources); or virtual (such as cyber, electronic data, and information systems)". "Criticality is often in the eyes of the beholder and is dependent upon a given situation. The large and diverse number of critical assets within a region, constrained state and local resources, and our need to gain better understanding of infrastructure interdependencies require the development of criteria for and a risk-based approach to identifying critical assets". (The Infrastructure Security Partnership, Regional Disaster Resilience, 2006, pp. 3-4)