Critical infrastructure and key resources (CIKR) is the totality of natural and man-made resources upon which a nation depends on for functioning, along with the systems for their processing, delivery and protection.
Critical infrastructure includes transport, energy, IT, communications, agricultural, food and water systems, as well as other sectors. In the United States, the government has identified 16 sectors of critical infrastructure. CIKR includes the resources involved with those systems as well as the core services -- such as police, intelligence communities and the military -- that defend them. Elements of critical infrastructure are interconnected and dependent on many outside elements that in turn are planned for, managed and defended to enable the nation’s support of its citizens and economy.
Within the United States, the Critical Infrastructure Protection Program was enacted within the Patriot Act in 1996. Critical infrastructure security has become an increasingly serious concern as the systems involved are more frequently becoming connected and, as a result, more vulnerable to attack.