Syrian rebel and opposition groups have rejected Russia's proposed peace talks next month, accusing Moscow of what they called "war crimes" in Syria and failing to put pressure on the Syrian government to end the six-year civil war.
In a series of statements on December 26, 40 rebel groups, including some of Syria's most prominent, as well as political opposition groups, said the talks planned next month are an attempt to "circumvent" the UN-led peace process, which has made virtually no progress since it began in 2014.
The rebel groups said Moscow has asked them to give up their demand that Syrian President Bashar al-Assad, whose troops Russia has backed with a devastating air campaign since 2015, step down as part of a political settlement.
"We reject this, and we affirm that Russia is an aggressor that has committed war crimes against Syrians," the statement, signed by 40 rebel groups, said.
"Russia has not contributed with a single move to alleviate the suffering of the Syrian people, and it has not pressured the regime it claims it guarantees to move an inch toward any real path toward a resolution."
The rebel groups, including Ahrar al-Sham, Army of Islam, and a number of Western-backed outfits, said they are committed to the UN-led process.
More than 330,000 people have been killed in Syria and millions have been driven from their homes since the conflict began in March 2011 with a crackdown on antigovernment protests.
The Kremlin has announced it will host a "Syrian national dialogue congress" in Sochi on January 29-30 and has cast the event as a broadening of "technical" talks aimed at working out cease-fire deals that Russia has co-sponsored with Iran and Turkey in the Kazakh capital, Astana, this year.
Syria's government has said it will attend the forum. Assad told reporters recently that the Sochi talks have an agenda of discussing new elections and possibly amending the constitution.
Russia's proposal was also endorsed by Iran, a key Syrian ally that has provided military advisers and militia fighters backing Assad during the war, and Turkey, which backs many of the Sunni rebel groups.
But the wholesale rejection of the Sochi forum by most rebel and political opposition groups, as well as by governing bodies in rebel-held areas of Syria, appears to threaten the viability of the Russian plan.
Russia has touted the planned Sochi talks as an effort to revive United Nations-sponsored negotiations that have repeatedly failed to reach a settlement in Syria. But its plans are also threatened by disagreement over whether to include Syrian Kurdish groups.
Turkey has ruled out inviting the powerful PYD Kurdish group, which governs around 25 percent of Syria's territory and wants autonomous rule there. Ankara views the PYD as an extension of militant Kurdish separatist groups in Turkey that it has been battling for decades.
Russia said last week that Kurdish representatives would attend the talks, but in a bow to Turkey, Moscow said it would not invite the PYD.
But the PYD-led self-administration authority in northeastern Syria, where the PYD is dominant, said that the authority, not individual parties, should be represented at the Sochi talks.
The PYD is the main political arm of the U.S.-allied Kurdish militia that recently played a major role in defeating the Islamic State extremist group in the region.