US President Donald Trump said on Monday that the war against Iran may be short-lived, despite the country’s selection of a new hard-line supreme leader to oversee the fight for the Islamic theocracy’s survival.But moments later, Mr Trump hinted during a news conference that the worst fighting could still be ahead as he threatened intensified action if Iran made any “attempt to stop the globe’s oil supply”.The back-and-forth sent oil prices and stock markets see-sawing.