"The Russians are playing a very, very malign role in Syria, despite the recent pronouncement by the Kremlin…of a political solution," DOD strategic communications advisor to the National Coalition of Syrian Revolution and Opposition Forces, Oubai Shahbandar said Friday.
Meanwhile, former US Ambassador to Syria, Robert Ford, said it is a "big question" whether or not the Russian initiative "will produce enough of a change in Damascus that the people fighting the regime in Damascus would accept to stand down".
Ford also said that, in his opinion, Russia does not "fully understand that there has to be a political angle, as well as a security angle" is resolving the situation in Syria.
Russian Deputy Foreign Minister stated on Wednesday that if Syrian officials wanted to meet in Moscow, he would discuss the issue with the United States. Meanwhile, the White House maintains its position that there must be a political transition in Damascus as part of the "endgame" for stability in the region.
IS is a radical Sunni group that has been fighting the Syrian government since 2012, having also spread its activities to Iraq.
The United States is currently leading an international anti-IS coalition, which has been conducting airstrikes in Syria and Iraq since September. US anti-IS efforts also include training and equipping Syrian rebels.