Dwindling global refinery capacity is threatening to turn what started as a Middle East oil-supply crisis into a more complex global oil headache impacting gasoline, diesel and other fuels. Drone and missile attacks launched by the Iran-backed Houthis on refineries and oil infrastructure in Saudi Arabia have aggravated long-brewing problems with the supply of Middle Eastern oil products. Further refinery constraints in Russia and China have added to the bottleneck of refined products.