Columbia subject headings:
Aeronautics, Commercial--Security measures.
National security--United States.
Terrorism--Prevention--Government policy--United States.
Terrorism--Prevention--Technological innovations.
Terrorism--United States--Prevention.
Harvard subject headings:
Terrorism--Prevention--Technological innovations.
Terrorism--Technological innovations--United States.
Princeton subject headings:
Aeronautics, Commercial--Security measures.
Terrorism--Prevention--Technological innovations.
Terrorism--United States--Prevention.