U.N. special envoy Staffan de Mistura’s recent statement blaming the Syrian regime (I can't find any such statement) for obstructing negotiations was not as strong as it should have been, considering the murder and displacement of hundreds of thousands of civilians.
Russia and Iran are trying to establish a state whose ethnic components suit the capabilities of Assad, who belongs to a sect that only constitutes 10 percent of the population.Abdulrahman al-Rashed
The Syrian opposition was asked to accept maintaining the regime in order to avoid state collapse and not repeat the American mistake in Iraq. The opposition said it was willing to participate in a unity government but without Assad. Then it was told to communicate and negotiate with the Russians to end the crisis. The opposition went to Moscow but heard only threats. One of the participants commented: “What is left in Syria for us to fear?”