33 CFR 165.30: Security zones.

(a) A security zone is an area of land, water, or land and water which is so designated by the Captain of the Port or District Commander for such time as is necessary to prevent damage or injury to any vessel or waterfront facility, to safeguard ports, harbors, territories, or waters of the United States or to secure the observance of the rights and obligations of the United States.

(b) The purpose of a security zone is to safeguard from destruction, loss, or injury from sabotage or other subversive acts, accidents, or other causes of a similar nature:

(1) Vessels,

(2) Harbors,

(3) Ports, and

(4) Waterfront facilities:

in the United States and all territory and water, continental or insular, that is subject to the jurisdiction of the United States.