NATO naval forces, which tipped off Greece to a ship in its waters carrying 680 tonnes of explosive, are hunting a list of 20 "suspect" vessels that intelligence trackers say could be used by terrorists. Lieutenant Commander Harvey Burwin said "Operation Active Endeavour" began in October 2001 and covers the Mediterranean. Its activities have recently been stepped up, with suspicious vessels boarded and searched. "We look for ships that have had frequent changes of flag and ownership," he said. Asked if the ships on the list were suspected of being operated by militant groups like al-Qaeda, he replied: "Yes at...