Columbia subject headings:
National security--United States.
Terrorism--Prevention--Government policy--United States.
Terrorism--United States--Prevention.
Terrorism.
Harvard subject headings:
National security--United States
Terrorism
Terrorism--Government policy--United States
Terrorism--Prevention--Government policy--United States
Terrorism--United States--Prevention
War on Terrorism, 2001-2009
Princeton subject headings:
National security--United States.
Terrorism--Government policy--United States.
Terrorism--United States--Prevention.
War on Terrorism, 2001-2009.