As the Syrian ceasefire took effect today, Turkey reiterated its “serious concerns” about the plan, after insisting in the last few days that they believed the ceasefire benefited the Russians, and that they don’t intend to be bound by the ceasefire themselves.
The big objection by Turkey though, as with everything even tangentially related to Syria, is the inclusion fo the Kurdish YPG in the ceasefire, saying that if the US and Russia want to exclude ISIS and al-Qaeda, they must also include the Kurds.
The ceasefire went into effect at midnight Syrian time, and has so far held. Though the ceasefire explicitly excludes both ISIS and the Nusra Front, there have not been reports of any major happenings in their territory since then either, nor has Turkey attacked the Kurds in Syria so far since then.
The YPG, like most of the groups that endorsed the ceasefire, says it reserves the right to respond if attacked. In their case, the most likely row would be with Turkey, as ISIS is not a party to the ceasefire, and is their primary other opponent.