Five U.S. Navy warships guided military-chartered tankers through the Persian Gulf on a supply run that has turned into one of the biggest oceangoing convoys since U.S. forces began escort operations in July. The miles-long convoy attracted several other merchant ships hoping for a safe journey through the tense waterway in the wake of an Iranian attack on a Greek tanker Tuesday night. Meanwhile, a Liberian-registered tanker was hit in the southern gulf by missile fire from an unidentified speedboat, oil industry sources said. The tanker Western City was attacked after loading crude oil at an Abu Dhabi installation. No casualties were reported, and damage to the ship was termed minor.