BEIRUT (Reuters) - Syrian President Bashar al-Assad on Monday described U.S.-backed militias in eastern Syria as  traitors , his office said in an online statement.  In a meeting with Russian Deputy Prime Minister Dmitry Rogozin at Syria s Hmeimim base, Assad also welcomed a United Nations role in Syrian elections as long as it was linked with Syria s sovereignty, his office cited him as saying. Assad has repeatedly vowed to take back all of Syria.  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 that now controls nearly a quarter of Syria.  The SDF said Assad s comments were no surprise, accusing his government of sowing strife and sectarianism.  We assert once again that we will go forward without hesitation in chasing terrorism,  it said in a statement.   This regime ... is itself a definition of treachery that, if Syrians do not confront it, will lead to partitioning the country, which our forces will not allow in any form,  the Kurdish-led SDF added. 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. 