http://www.spectrum.ieee.org/sep06/4441
Ted G. Lewis
"The science of networks analyzes the hidden weaknesses and strengths of critical infrastructures now at risk from terrorist attack. The fall of the Twin Towers on 9/11 cut off Internet service in South Africa. A cyberattack in 2003 shut down a section of the Internet, halting the Davis-Besse nuclear power plant in Ohio. Later that year, an apparently minor fault at FirstEnergy, an electric utility in Ohio, plunged 50 million North Americans into darkness.
Each case posed a problem of particular concern for homeland security: how to guard critical infrastructure that is so vast and complex that we cannot afford to protect every part or anticipate the ultimate effects of a disruption? Modern societies depend on such infrastructure for power, communications, transportation, and public health, yet everywhere governments are still addressing vulnerabilities one component at a time."