A senior Iranian military official on Monday threatened to “set on fire” any ships travelling through the Strait of Hormuz, the narrow waterway off Iran’s southern coast through which a fifth of the world’s oil travels.The threat, made by Ebrahim Jabari, an adviser to the commander of the Islamic Revolutionary Guard Corps, comes as most shipping companies have already stopped sending tankers through the strait, after the US and Israel began their strikes on Iran on Saturday. A few tankers have already come under attack during the conflict, including one on Monday that was flying the US maritime flag and was docked in Bahrain. It was not clear who attacked the vessel.“Not a single drop of oil will leave the region,” Jabari said on Iranian TV. Iran had on Saturday also said it was closing the strait, though some ships did travel through the waterway in the immediate aftermath of the American and Israeli attacks. The sharp reduction in tanker traffic through the strait is raising fears that significantly less oil and gas will make it onto world markets, pushing up the cost of both commodities. A prolonged increase in oil prices could lead to higher gas prices for consumers.