The war in Syria has been raging for nearly four years and it's been challenging for diplomats to get warring sides to agree on even temporary truces.
The U.N. envoy is pressing ahead on that front, while Russia tries to play peacemaker. Russia is inviting the parties to Moscow this month, but some opposition groups won't go to a country that has been backing Syrian President Bashar al-Assad.
Syrian opposition figures have good reason to be skeptical of Moscow's diplomatic moves, says Reza Afshar, a former British diplomat who now advises the Syrian opposition coalition.
"A process that is initiated by the Russians, who are a party to the conflict — they provide weapons and advice to the Assad regime and they have taken an approach of cherry-picking who they talk to and who the regime talks to — is obviously a process that is going to be concerning to some people, of course," Afshar says.