It was not immediately clear who was responsible for the strikes on a U.S.-owned floating storage facility and a Greek-owned tanker. The flare-up on multiple fronts, after several days of relative calm, raised the risk of a return to all-out war. A strike by Iran or its allies, if confirmed, would mark a significant widening of the conflict. Asked during an Oval Office event if Iran was responsible for the strikes on the natural gas vessels, Trump responded, “It’s a little more of the same.” Before the latest eruption, mediators had expressed optimism about bringing the U.S. and Iran back to the negotiating table.