Whenever, during any war in which the United States is neutral, the President, or any person thereunto authorized by him, shall have cause to believe that any vessel, domestic or foreign, whether requiring clearance or not, is about to carry out of a port or from the jurisdiction of the United States, fuel, men, arms, ammunition, implements of war, supplies, dispatches, or information to any warship, tender, or supply ship of a state named in a proclamation issued under the authority of section 441(a) of this title, but the evidence is not deemed sufficient to justify forbidding the departure of the vessel as provided for by section 967 of title 18, and if, in the President’s judgment, such action will serve to maintain peace between the United States and foreign states, or to protect the commercial interests of the United States and its citizens, or to promote the security or neutrality of the United States, he shall have the power, and it shall be his duty, to require the owner, master, or person in command thereof, before departing from a port or from the jurisdiction of the United States, to give a bond to the United States, with sufficient sureties, in such amount as he shall deem proper, conditioned that the vessel will not deliver the men, or any fuel, supplies, dispatches, information, or any part of the cargo, to any warship, tender, or supply ship of a state named in a proclamation issued under the authority of section 441(a) of this title.

If the President, or any person thereunto authorized by him, shall find that a vessel, domestic or foreign, in a port of the United States, has previously departed from a port or from the jurisdiction of the United States during such war and delivered men, fuel, supplies, dispatches, information, or any part of its cargo to a warship, tender, or supply ship of a state named in a proclamation issued under the authority of section 441(a) of this title, he may prohibit the departure of such vessel during the duration of the war.

Whenever the President shall have issued a proclamation under section 441(a) of this title he may, while such proclamation is in effect, require the owner, master, or person in command of any vessel, foreign or domestic, before departing from the United States, to give a bond to the United States, with sufficient sureties, in such amount as he shall deem proper, conditioned that no alien seaman who arrived on such vessel shall remain in the United States for a longer period than that permitted under the regulations, as amended from time to time, issued pursuant to section 168 [1] of title 8. Notwithstanding the provisions of said section 168  of title 8, the President may issue such regulations with respect to the landing of such seamen as he deems necessary to insure their departure either on such vessel or another vessel at the expense of such owner, master, or person in command.

(Nov. 4, 1939, ch. 2, § 10, 54 Stat. 9.)