WASHINGTON/DUBAI/JERUSALEM- US President Donald Trump threatened to strike the oil infrastructure of Iran's Kharg Island hub unless Tehran stopped attacking vessels in the Strait of Hormuz, a warning that could further roil markets coping with a historic supply disruption.

Trump paired his Friday ultimatum with a social media post saying the U.S. had "totally obliterated" military targets on the island, the export terminal for 90% of Iran's oil shipments, which lies about 300 miles (500 km) northwest of the strait.

US strikes did not target Kharg's oil infrastructure, but "should Iran, or anyone else, do anything to interfere with the Free and Safe Passage of Ships through the Strait of Hormuz, I will immediately reconsider this decision," Trump wrote.

As the war entered its third week, Iran, however, struck a defiant note, playing down the extent of the damage on Kharg while threatening to step up its use of more powerful weapons and warning parts of the United Arab Emirates were a legitimate target.

"We declare to the leaders of the UAE that Iran considers it a legitimate right to defend its national sovereignty and territory by targeting the origin of American enemy missile launches in the shipping ports, docks, and military shelters of the U.S. hidden in some cities of the UAE," a spokesperson for Iran's Revolutionary Guards said.

In a statement, the IRGC urged residents in the UAE to evacuate ports, docks, and U.S. military shelters to avoid civilian casualties.

Nine ballistic missiles and 33 drones were launched from Iran towards the UAE on Saturday, the Ministry of Defence said, making a total of 294 ballistic missiles, 15 cruise missiles and 1,600 drones launched from Iran since the war started.

Behind the scenes, resentment had already been mounting in Gulf Arab capitals at being drawn into a war they neither initiated nor endorsed but are now paying for economically and militarily, regional sources have told Reuters.

Iran also vowed to increase its usage of upgraded weapons, particularly ballistic missiles and other missiles with greater destructive power, a defence ministry spokesperson was quoted as saying in state media.

Oil exports from Kharg Island were continuing normally despite the U.S. attack, a senior provincial governor was quoted by the IRNA news agency as saying. – Reuters