The airstrikes have added to rebels' doubts if any ceasefire could hold. (Representative image) Photograph: (Getty)
The agreement, by the powers that back opposing sides in the five-year-old Syria war, promises a nationwide truce from sundown on Monday
Razak, of the Nour al-Din al Zinki Brigades, part of the Free Syrian Army (FSA) which is backed by the West, said they were studying the peace deal but feared it merely gave the Syrian army a chance to gather forces and pour more Iranian-backed militias into Aleppo.
'Halting all attacks'
US Secretary of State John Kerry called on all sides to respect the deal, which was finally reached after several failed attempts over recent weeks.
"This requires halting all attacks, including aerial bombardments, and any attempts to gain additional territory at the expense of the parties to the cessation. It requires unimpeded and sustained humanitarian access to all of the besieged and hard-to-reach areas including Aleppo," he said.
Russian foreign minister Sergei Lavrov said that despite continuing mistrust, the two sides had developed five documents that would enable coordination of the fight against terrorism and a revival of Syria's failed truce.
Both sides agreed not to release the documents publicly.
"This all creates the necessary conditions for resumption of the political process, which has been stalling for a long time," Lavrov said.
The Nusra question
Previous peace efforts have crumbled within weeks, with the United States accusing Assad's forces of attacking opposition groups and civilians.
Kerry said the "bedrock" of the new deal was an agreement that the Syrian government would not fly combat missions in an agreed area on the pretext of hunting fighters from the Nusra Front, an al-Qaeda affiliate in Syria which has recently changed its name to Jabhat Fateh al-Sham.
Under the new deal, both sides - Russian-backed government forces and rebel groups supported by the U.S. and Gulf states, - are to halt fighting as a confidence building measure.
If the truce holds from Monday, Russia and the United States will begin seven days of preparatory work to set up a "joint implementation centre", where they will share information to distinguish territory controlled by Nusra from that held by other rebel groups.
For many FSA rebels, the idea of a clear separation from Nusra is problematic because on several fronts they fight together against the army and allied Iranian-backed militias.
Fateh al-Sham has also played a major role in trying to end the siege of eastern Aleppo which many rebels say has boosted its popularity, and discussions are ongoing to possibly unify ranks under a broader opposition army.
"Fateh al-Sham is a faction present on the ground and it takes part in most of the military operations, and the matter of separating it is not possible, particularly given that there are attempts to merge, within some factions, with Fateh al-Sham," Fares al-Bayoush, head of an FSA group called the Northern Division, told Reuters.