Armed men wearing masks reportedly boarded the vessel close to the Omani port of Sohar. The armed men then ordered the ship’s crew to sail to an Iranian port. Iranian state media, quoting the Navy, reported that the ship was seized in retaliation for the ship and the oil it had aboard being confiscated by the US last year.

The St. Nikolas was in transit between the Iraqi port of Basra and its intended destination in Turkey.

On Thursday, the UK Maritime Trade Operations said it had received a report that four to five armed men dressed in black masks and military fatigues. They had reportedly boarded the ship at 03:30 UTC. They then added that communications were lost with the vessel. They stated that authorities were investigating the incident.

Iranian state media quoted the military stating that the vessel was American when in reality it is Greek-owned.

The company managing the ship stated that the vessel was carrying 145,000 tons of crude oil. It also had carried 18 Filipinos and 1 Greek as crew.

The St Nikolas was seized in April by the United States Navy when it was operating under a different name, the Suez Rajan. It was seized as part of sanctions enforcement against Iran. Suez Rajan Limited, the company that formerly chartered the ship, later pleaded guilty to conspiring to violate sanctions by covertly selling and transporting oil on behalf of Iran.

The US called for the immediate release of the vessel as well as its crew and described the situation as the latest attempt by Iran to disrupt global commerce.

“We believe this kind of action will simply add uncertainty for commercial shipping and for regional and global economies,” said US spokesman Vedant Patel.

This incident was in a different sea from where the Houthis have been attacking Iraeli-linked shipping in the Red Sea. The US and the UK have already launched strikes on Houthi installations and bases in Yemen.