Electric power is essential to the functioning of U.S. society. The electric power system increasingly operates at or near its reliability limits. The geographic scale of the tightly coupled networks involved makes the system susceptible to large-scale outages. More frequent natural and accidental failures portend possible catastrophes from intentional disruption. Deregulation has been a major factor to the lack of investment in system upgrades. Techniques to prevent attacks and reduce vulnerabilities are available and affordable.