Russian oil has stopped flowing through a pipeline that feeds countries in Central and Eastern Europe, dealing another blow to a region contending with the loss of vital energy supplies from Russia. Transneft PJSC, the government-owned oil-pipeline operator, said Tuesday that crude exports through Ukrainian territory had halted on Aug. 4. It blamed payment difficulties caused by Western sanctions on Moscow and said Ukraine’s pipeline operator had declined to carry crude after it didn’t receive funds. A spokeswoman for Naftogaz NJSC, Ukraine’s state energy firm and the parent company of pipeline operator Ukrtransnafta, said it would issue a statement later...