The US military will enforce a blockade in the Gulf of Oman and Arabian Sea east of the Strait of Hormuz and it will apply to all vessel traffic regardless of flag, the US Central Command said in a note to seafarers seen by Reuters on Monday. The note said the blockade would come into effect at 1400 GMT on Monday.

"Any vessel entering or departing the blockaded area without authorization is subject to interception, diversion and capture," the note said.

"The blockade will not impede neutral transit passage through the Strait of Hormuz to or from non-Iranian destinations."

The blockade "encompasses the entirety of the Iranian coastline to ⁠include but ⁠not limited to ports and oil terminals," the note said, adding that humanitarian shipments including food, medical supplies and other essential goods would be ⁠permitted, subject to inspection.

Tehran has threatened to retaliate against ports of its Gulf neighbours, after weekend ⁠talks failed to reach a deal to end the war, leaving a ceasefire in jeopardy.