There are a number of ways the Royal Navy can detain ships, says Prof Kevin Rowlands from the Royal United Services Institute (RUSI) and a former Navy captain.
“First, identifying and tracking the vessels is reasonably straight forward. The list of shadow fleet ships is well known and surveillance in UK waters is pretty comprehensive.
“Boarding will depend on the type of ship, its location, and local sea and weather conditions at the time. It could be by boat or, more likely, by helicopter.”
“The navy has boarding teams consisting of sailors and Royal Marines. They are trained to safely embark on the ship, liaise with the crew, search the vessel, check paperwork and, if necessary, divert it under escort to a UK port.”