For the first time in the current ceasefire, Russian forces reportedly intervened today to prevent fighting between two parties of the deal, the Syrian military and a group of rebels backed by the Turkish military. The incident took place just southwest of the Aleppo Province town of al-Bab.
The rebels are blaming the Syrian military for the fighting, saying that they fired first and that they simply retaliated, with Russian forces quickly getting in the middle of the situation and calming everyone down. The rebels claimed to have captured a military vehicle.
Turkey has been trying to get al-Bab under control for awhile, with a lot of rebels helping them. The Syrian military had been driving al-Qaeda forces out of the area around Aleppo city, putting them into close proximity as well, fueling fears that close proximity could bring them into direct conflict.
With Russia working closely with both the Syrian and Turkish militaries, they were in a good position to step in in this case and split them apart when the fighting erupted. Keeping the two sides apart may be a long-term problem, with al-Bab still a goal of both sides.