“ Those instructions to the Coast Guard shall include appropriate directives providing for the Coast Guard: (1) To stop and board defined vessels, when there is reason to believe that such vessels are engaged in the irregular transportation of persons or violations of United States law or the law of a country with which the United States has an arrangement authorizing such action. (2) To make inquiries of those on board, examine documents and take such actions as are necessary to establish the registry, condition and destination of the vessel and the status of those on board the vessel. ”