Columbia subject headings:
Harbors--Security measures--United States.
National security--Law and legislation--United States.
Ports of entry--Security measures--United States.
Risk management--Government policy--United States.
Shipping--Security measures--United States.
Harvard subject headings:
Harbors--Security measures--United States
National security--Law and legislation--United States
Ports of entry--Security measures--United States.
Risk management--Government policy--United States.
Shipping--Security measures--United States
Princeton subject headings:
Harbors--Security measures--United States.
National security--Law and legislation--United States.
Ports of entry--Security measures--United States.
Risk management--Government policy--United States.
Shipping--Security measures--United States.