Critical infrastructure is a term used in the USA's National Strategy for Homeland Security, which was issued in July 2002; it is defined as those "systems and assets, whether physical or virtual, so vital to the United States that the incapacity or destruction of such systems and assets would have a debilitation impact on security, national economic security, national public health or safety, or any combination of those matters."

The thirteen sectors of critical infrastructures and the agency liaisons identified by the National Strategy for Homeland Security are the following:

1. Agriculture – Department of Agriculture
2. Food – Departments of Agriculture and Health and Human Services
3. Water – Environmental Protection Agency
4. Public Health – Department of Health and Human Services
5. Emergency Services – Department of Homeland Security
6. Government – Department of Homeland Security
7. Defense Industrial Base – Department of Defense
8. Information and Telecommunications – Department of Homeland Security
9. Energy – Department of Energy
10. Transportation – Department of Homeland Security
11. Banking and Finance – Department of the Treasury
12. Chemical Industry and Hazardous Materials – Department of Homeland Security
13. Postal and Shipping – Department of Homeland Security