Critical infrastructure – both physical and cyber – is the backbone of America’s national security and economic prosperity. The Nation’s critical infrastructure is diverse and complex. It includes distributed networks, varied organizational structures and operating models (including multi-national ownership), interdependent functions and systems in both physical space and cyberspace, and governance constructs that involve multi-level authorities, responsibilities, and regulations. Critical infrastructure faces a variety of risks to its security and ability to function, including manmade acts of terror, extreme weather events, other natural disasters and cyber attacks.