Tehran - Iran's Islamic Revolutionary Guards Corps (IRGC) threatened Saturday to target US sites in the Middle East if its tankers come under fire.
"Any attack on Iranian tankers... will result in a heavy attack on one of the American centres in the region," the Guards said, after US strikes disabled two Iranian-flagged tankers in the Gulf of Oman.
President Donald Trump said Friday he expected Tehran's answer to Washington's latest peace proposal "supposedly tonight."
But Iran's Foreign Minister Abbas Araghchi questioned US seriousness on diplomacy, calling recent American actions in the Persian Gulf a violation of the ceasefire.
The incident follows weeks of tension in the Strait of Hormuz, where Iran seeks to control the key oil route. Washington has sent a proposal via Pakistani mediators to extend the truce and negotiate a final settlement.
Meanwhile, satellite images show an oil slick spreading off Iran's Kharg Island, a critical export terminal. The cause remains unclear.
A parallel ceasefire with Hezbollah on the Lebanon front is also under strain, with nine killed in Israeli strikes Saturday and Hezbollah responding with drone attacks on northern Israel. Direct Lebanon-Israel negotiations are scheduled for Washington next week.