"Critical infrastructure includes those assets, systems, networks and functions-physical or virtual-so vital to the United States that their incapacitation or destruction would have a debilitating impact on security, national economic security, public health or safety or any combination of those matters. Key resources are publicly or privately controlled resources essential to minimal operation of the economy and the government". (DHS, Private Sector and Nongovernmental Organizations Response Partner Guide (Draft), Sep.10, 2007, p. 2)