Iran’s Revolutionary Guards said on Tuesday they would not let any oil be shipped from the Middle East ​if U.S. and Israeli attacks continue, prompting President Donald Trump to say the U.S. would hit Iran much harder if it blocked exports.

The rhetoric did little to quell a fall ‌in crude prices and a rally in global shares that followed Trump expressing confidence in a swift end to hostilities, even after Iran showed defiance by naming Mojtaba Khamenei as its new supreme leader.