Reuters - Oil prices erased some of their previous gains on Thursday, despite escalating attacks in the Gulf as investor focus shifted to supply flows through the ​key chokepoints in the region. On Wednesday, the U.S. and Saudi Arabia attacked Iran-backed paramilitary forces in Iraq, the first ​time that Saudi had publicly joined U.S. air strikes, in retaliation for drone attacks on Saudi oil targets launched ​from Iraq. The U.S. also carried out two hours of attacks on Iran on Wednesday, the U.S. Central Command said. Iran closed ​the waterway, through which around ​a fifth of global ⁠oil and gas flows previously passed, after the U.S.-Israeli war began on February 28. Rystad Energy estimates about 13 million barrels per day of oil from the Gulf is ​still reaching markets.