The Captain of the Port may prevent any person, article, or thing from boarding or being taken or placed on board any vessel or entering or being taken into or upon or placed in or upon any waterfront facility whenever it appears to him that such action is necessary in order to secure such vessel from damage or injury or to prevent damage or injury to any vessel, or waterfront facility or waters of the United States, or to secure the observances of rights and obligations of the United States. [E.O. 11249, 30 FR 13001, Oct. 13, 1965]