BEIRUT- Syrian President Bashar al-Assad on Monday described U.S.-backed militias in eastern Syria as "traitors", his office said in an online statement.Assad said he also welcomed a United Nations role in Syrian elections as long as it was linked with Syria's sovereignty, it cited him as saying in a meeting with Russian Deputy Prime Minister Dmitry Rogozin in Syria's Hmeimim base.A U.S.-led international coalition against Islamic State has given military support to the Syrian Democratic Forces (SDF), an alliance of Kurdish and Arab militias which now controls nearly a quarter of Syria.Assad has previously vowed to take back all of Syria.Rogozin was quoted by Russia's RIA news agency as saying after the meeting with Assad that Russia would be the only country to take part in rebuilding Syrian energy facilities. (Reporting by Sarah Dadouch; editing by Richard Balmforth) ((Sarah.Dadouch@thomsonreuters.com;))