Iranian forces seized an oil tanker sailing in the Gulf of Oman, diverting the vessel toward the country’s territorial waters on Friday after it passed the Strait of Hormuz, a US defense official said.

A Marshall Islands-flagged oil tanker sailing from the United Arab Emirates to Singapore made a sudden course change and was heading toward Iranian territorial waters, British maritime security firm Ambrey said on Friday.

Revolutionary Guards were reported by maritime security to have intercepted the oil products tanker, Talara, taking it into Iranian waters.

A tanker transiting through the narrow Strait of Hormuz suddenly changed course into Iranian territorial waters Friday, with the British military warning a possible “state activity” affected it. The warning from the British military’s United Kingdom Maritime Trade Operations center comes as a private security firm said small vessels had intercepted the ship earlier.