Parts of Syria saw continued fighting Saturday, on the second day of a nationwide ceasefire intended to pave the way for peace talks between the government and the opposition in the new year.
Activists reported pro-government forces were pressing on several fronts against two strategically-located opposition pockets around the capital, Damascus, while Russia's military deployment to Syria reported twelve ceasefire violations it blamed on rebels Friday. Russia is a key ally of the Syrian government.
Nevertheless, the Russian and Turkish brokered truce held for the most part on a day marked by rain and overcast skies, preserving the possibility for peace talks in the Kazakhstan capital of Astana in the second half of January.
The UN Security Council is scheduled to meet at 11am EST (4pm GMT) to vote on a resolution to endorse the ceasefire and roadmap to peace beginning with a transitional government for the country.
The resolution also calls for the "rapid, safe and unhindered" access to deliver humanitarian aid throughout the country.
The developments signal the possibility of a diplomatic breakthrough after nearly six years of conflict that has drawn in world powers, displaced half the Syrian population, and killed more than 400,000 people. The parties have defied previous peace initiatives.
It follows months of talks between Ankara and Moscow that culminated in a ceasefire agreement that went into effect Thursday at midnight.
Moscow along with Iran provides crucial military support to Syrian President Bashar Assad, while Turkey has long served as a rear base and source of supplies for the opposition.
The three powers, Russia, Iran, and Turkey, have agreed to sponsor talks between the government and the opposition in Astana if the truce holds holds.
Syrian rebel groups warned they would consider the ceasefire "null and void" if the Assad government's forces and their allies continued to violate it.
"Continued violations by the regime and bombardment and attempts to attack areas under the control of the revolutionary factions will make the agreement null and void," a statement signed by a number of rebel groups said.
The statement said government forces and their allies, including Lebanese terror organization Hezbollah, had been trying to press advances, particularly in an area northwest of Damascus in the rebel-held Barada Valley.
Rebels say the army is seeking to recapture the area, where a major spring provides most of Damascus's water supplies.
The Britain-based Syrian Observatory for Human Rights monitoring group said at least two civilians and five militants have been killed in battles over opposition-held Eastern Ghouta and Barada Valley regions around Damascus, since the truce came into effect Thursday at midnight.
The Barada Valley Media Center said Russian and Syrian government aircraft struck villages in the water-rich region for the 10th consecutive day Saturday. The raids have coincided with a severe water shortage in Damascus since Dec. 22.
Blasts from government shellfire were also heard in the southern provinces of Quneitra and Deraa, the Observatory said.
Each side blames the other for continued unrest. Russia's defense ministry said on Friday rebels had violated the truce 12 times in 24 hours.
In their statement, the rebels said it appeared the government and the opposition had signed two different versions of the ceasefire deal, one of which was missing "a number of key and essential points that are non-negotiable", but did not say what those were.
Meanwhile, Turkey's state-run Anadolu news agency reported the death of an Islamic State commander in a Turkish airstrike near the north Syrian town of al-Bab on Friday. The truce does not cover operations against the Islamic State or al-Qaida's Syria affiliate, the Fatah al-Sham front.
Anadolu identified the commander as Abu Ansari. The report could not be independently verified.