Iraq has rejected ExxonMobil’s effort to sell its stake in the West Qurna 1 oil field to two Chinese companies, raising a cloud of uncertainty and potential conflict over a project responsible for about one-tenth of the country’s oil output. In a letter to Exxon dated May 13, which two Iraqi oil officials confirmed as authentic, the state-run Basra Oil Company (BOC) said, “We’d like to let you know that we don’t agree with the terms you’ve agreed to with the two companies listed above,” which the letter identifies as the China National Petroleum Corp. (CNPC) and the China National Offshore Oil Company (CNOOC).