Whoever brings, carries, or possesses any such weapon or explosive on board of any vessel in the possession and under the control of the United States or which has been seized and forfeited by the United States or upon which a guard has been placed by the United States pursuant to the provisions of section
191 of Title
50, without previously obtaining the permission of the captain of the port in which such vessel is located, shall be fined under this title or imprisoned not more than one year, or both.