Columbia subject headings:
Harbors--Security measures--United States.
National security--United States.
Shore protection--United States.
United States. Coast Guard.
Waterways--Security measures--United States.
Harvard subject headings:
Harbors--Security measures--United States
National security--United States
Shore protection--United States.
United States. Coast Guard.
Waterways--Security measures--United States.
Princeton subject headings:
Coastal surveillance--United States.
Harbors--Security measures--United States.
National security--United States.
United States. Coast Guard
Waterways--Security measures--United States.