The customs duties leviable on goods destined for the interior shall be collected at the port of entry and handed over to the administration of the area of destination.

BBC: Map detailing the Sykes-Picot agreement

The World Shipping Council has already argued that vessels should be stopped and inspected, if necessary, not at the initial port of entry in America but at their ultimate destination.

ECONOMIST: In peril on the sea | The

The ring road around the western city of Caen was also blocked, and more barricades were set up near the northern port of Le Havre, and at a key entry point to the motorway from the north to Paris.

BBC: French blockades herald travel chaos

"Just two weeks before we launched the airline in March, we were advised by the French authorities that there would be a short delay of a couple of weeks before a customs and immigration port of entry was in place at Paris Pontoise, " he said.

BBC: Let-410 aircraft