The Strait of Hormuz’s southern route remained open to shipping on Sunday despite Iran declaring the waterway closed as tit-for-tat attacks between the US and Tehran escalated, a maritime advisory group said.

The path along the Omani coastline is still available for transit, the Joint Maritime Information Center said in a note. Describing the threat-level in the strait as still “severe,” it told mariners to expect radio communications with naval forces and be aware of a danger from mines.

Iran’s Islamic Revolutionary Guard Corps announced earlier Sunday it wouldn’t allow any vessels to pass the strait until foreign interference ends, accusing the US of seeking to create disruptions.

American forces struck Iran for a third time in a week overnight, after a Cyprus-flagged container ship was hit nine nautical miles off the Omani coast, causing a fire and forcing the crew to abandon the vessel.

Read More: US, Iran Trade Wave of Attacks as Tehran Says Hormuz Closed