Columbia subject headings:
National security--Law and legislation--United States.
Terrorism--Prevention--Government policy--United States.
United States. Dept. of Homeland Security.
Harvard subject headings:
National security--Law and legislation--United States
Terrorism--Prevention--Government policy--United States
United States. Department of Homeland Security.
Princeton subject headings:
National security--Law and legislation--United States.
Terrorism--Prevention--Government policy--United States.
United States. Department of Homeland Security