Columbia subject headings:
Border patrols--United States.
Harbors--Security measures--United States.
National security--United States.
Nuclear terrorism--United States--Prevention.
Harvard subject headings:
Border patrols--United States
Harbors--Security measures--United States
National security--United States
Nuclear terrorism--United States--Prevention.
Princeton subject headings:
Border patrols--United States.
Harbors--Security measures--United States.
National security--United States.
Nuclear terrorism--United States--Prevention.