The nation’s critical infrastructure provides the essential services that underpin American society and serve as the backbone of our nation's economy, security, and health. We know it as the power we use in our homes, the water we drink, the transportation that moves us, and the communication systems we rely on to stay in touch with friends and family.

Presidential Policy Directive-21 (PPD-21), “Critical Infrastructure Security and Resilience,” spells out the policy for how the federal government builds trusted partnerships and “advances a national unity of effort to strengthen and maintain secure, functioning, and resilient critical infrastructure.”

There are 16 critical infrastructure sectors whose assets, systems, and networks, whether physical or virtual, are considered so vital to the United States that their incapacitation or destruction would have a debilitating effect on security, national economic security, national public health or safety, or any combination thereof.

Sector-Specific Agencies

Each of these 16 critical infrastructure sectors has a designated Sector-Specific Agency (SSA) as identified in PPD-21:

• Chemical Sector – Department of Homeland Security
• Commercial Facilities Sector – Department of Homeland Security
• Communications Sector – Department of Homeland Security
• Critical Manufacturing Sector – Department of Homeland Security
• Dams Sector – Department of Homeland Security
• Defense Industrial Base Sector – Department of Defense
• Emergency Services Sector – Department of Homeland Security
• Energy Sector – Department of Energy
• Financial Services Sector – Department of the Treasury
• Food and Agriculture Sector – Department of Agriculture and Department of Health and Human Services
• Government Facilities Sector – Department of Homeland Security and General Services Administration
• Healthcare and Public Health Sector – Department of Health and Human Services
• Information Technology Sector – Department of Homeland Security
• Nuclear Reactors, Materials, and Waste Sector – Department of Homeland Security
• Transportation Systems Sector – Department of Homeland Security and Department of Transportation
• Water and Wastewater Systems Sector – Environmental Protection Agency

Each of these critical infrastructure sectors has unique characteristics, operating models, and risk profiles. As such, each SSA leverages their particular knowledge and expertise to:

• Coordinate and collaborate with DHS and other relevant Federal departments and agencies, with critical infrastructure owners and operators, where appropriate with independent regulatory agencies, and with SLTT entities, as appropriate, to implement PPD-21.
• Serve as a day-to-day Federal interface for the dynamic prioritization, collaboration, and coordination of sector-specific activities.
• Carry out incident management responsibilities consistent with statutory authority and other appropriate policies, directives, or regulations.
• Provide, support, or facilitate technical assistance and consultations for that sector to identify vulnerabilities and help mitigate incidents, as appropriate.
• Support the Secretary of Homeland Security’s statutory reporting requirements by providing, on an annual basis, sector-specific critical infrastructure information.

For more details on how PPD-21 directs SSAs, please see “Appendix B: Roles, Responsibilities, and Capabilities of Critical Infrastructure Partners and Stakeholders” in the National Infrastructure Protection Plan (NIPP) 2013.