The US military says one of the oil tankers attacked in the Gulf of Oman last week was damaged by a mine resembling those used by the Iranian security forces.
The attack was the second such incident in the strategic shipping lane in a month.
Tehran has denied any involvement.
The BBC was one of a small number of media outlets taken out by US Navy off coast of the United Arab Emirates to see the stricken ship.
Gulf crisis: Close up to stricken oil tanker with the US Navy