Russian Foreign Minister Sergey Lavrov has accused the US of "flirting with terrorists" in Syria. He said the US does not want to separate the moderate opposition from the al-Qaida affiliate al-Nusra.

He said, "We hope that the instinct of self-preservation will prevail. Because flirting with terrorists and trying to use them for your own goals has never led to anything good. And, as a result, these terrorists turned their guns against those who tried to handle them. Americans, as everybody else, know that."

However, a State Department spokesman fought back that the regime of Bashar Assad, with the backing of Russia, is laying siege on Aleppo, directly targeting civilians and civilian infrastructure.

The comments came after Russia and the Syrian government halted airstrikes on the eastern rebel-held part of Aleppo since last week, to allow for the evacuation of the wounded and civilians. But no evacuation took place and efforts to allow medical and food supplies into the besieged area also faltered. Meanwhile, pro-government troops kept up a ground offensive against rebel-held areas.