[t]he ability to prepare for and adapt to changing conditions and withstand and recover rapidly from disruptions; includes the ability to withstand and recover from deliberate attacks, accidents, or naturally occurring threats or incidents.
Resilience is the adaptive capability of an organization in a complex and changing environment.
the ability of an architecture to support the functions necessary for mission success with higher probability, shorter periods of reduced capability, and across a wider range of scenarios, conditions, and threats, in spite of hostile action or adverse conditions. . . . [R]esilience may leverage cross-domain or alternative government, commercial, or international capabilities.
The challenge facing government is to maintain its role in protecting critical infrastructures, while determining how best to encourage market forces to improve the resilience of companies, provide appropriate incentives and tools to help entire sectors become resilient, and step in when market forces alone cannot produce the level of infrastructure security needed to protect citizens, communities, and essential economic systems.