Pakistan, Aug. 15 -- Oil prices were stable on Thursday as investors weighed the potential impact of the upcoming U.S.-Russia summit on Ukraine on Russian crude flows, after U.S. President Donald Trump warned of "severe consequences" for Moscow if it does not agree to peace. Brent crude futures were up 49 cents, or 0.75%, at $66.12 a barrel by 1303 GMT, while U.S. West Texas Intermediate crude futures rose 51 cents, or 0.81%, to $63.16. Both contracts hit their lowest levels in two months on Wednesday after bearish supply guidance from the U.S. government and the International Energy (IEA). Trump on Wednesday threatened "severe consequences" if Russian President Vladimir Putin does not agree to peace in Ukraine. The U.S. president did not...