Summary

Certainly, the 1995 Tokyo Subway Attacks raised the specter of terrorist WMD attacks. They also raised concern about attacks against critical infrastructure. As 9/11 later demonstrated, subverting critical infrastructure can achieve WMD effects without the use of WMD. So, what is critical infrastructure? They are basic services needed to sustain society. Societies are human organizations. Critical infrastructure sustain human organization. What constitutes critical infrastructure depends upon the complexity of the society. Nomadic and agrarian societies require less critical infrastructure than urban societies. For American society, Presidential Policy Directive #21 identifies 16 critical infrastructure sectors. Among those 16 infrastructure sectors, four in particular are considered so important they are called “lifeline” infrastructure. Without them, the other sectors could not function. The four lifeline sectors are water, energy, transportation, and communications.