Russia and Turkey agreed during a summit meeting in the Black Sea resort city of Sochi on September 17 to set up a buffer zone in Idlib aimed at preventing a regime assault.
Syrian opposition said on Thursday they have growing confidence that their militant rivals will comply with a requirement to leave a demilitarised buffer zone set up by Turkey and Russia to avert a Russian-backed Syrian regime offensive.
Last week Turkey and Russia agreed to enforce a new demilitarised zone in Idlib province from which "radical" rebels will be required to withdraw by the middle of next month.
The position of the biggest militant group, Hayat Tahrir al Sham, spearheaded by Al Qaeda's former Syrian offshoot, will be crucial to the deal's success, but it has so far said nothing.
Several opposition sources said neither militant nor mainstream rebels had started to pull back yet.
However, a senior Syrian opposition official said Hayat Tahrir al Sham had sent secret feelers to the Turkish army though third parties in recent days signalling it would comply.
"Matters are moving well and Hayat Tahrir al Sham has pledged it is going to implement but without announcing its agreement," said the opposition official, who was briefed by Turkish officials and requested anonymity due to the sensitivity of the matter.
The demilitarised zone will be 15 to 20 kilometres deep, run along the contact line between opposition and regime fighters, and will be patrolled by Turkish and Russian forces. The agreement could unravel quickly if they cannot impose their plan on the militants.
Another senior opposition figure said he expected Hayat Tahrir al Sham to implement the deal and dismissed risks of a showdown because the agreement did not seek to force militants to hand over their weapons.
"I foresee it will be implemented within the time set," said Ahmed Toma, a prominent opposition figure who headed the Syrian rebel delegation in Russian-sponsored talks in the Kazakh capital.
TRT World's Sara Firth reports on the mood among opposition fighters in the wake of the deal.
Dodging an offensive for peace
Turkey sought to avert the Syrian regime's Idlib offensive, fearing a new exodus of refugees as the UN warned of a humanitarian catastrophe. Ankara pledged to Moscow it would handle the militant threat.
A regional intelligence source said the militants were softening their stance to avoid internecine fighting with mainstream rebels that could wreck the deal and allow the stalled offensive to resume.
"I don't expect any hurdles in implementation from all the revolutionary forces at all," said Abdul Salam Abdul Razzak, a leading figure in the National Front for Liberation, the alliance of Turkey-allied Free Syrian Army (FSA) opposition groups.
Turkish President Tayyip Erdogan said in an interview with Reuters late on Tuesday that the withdrawal of "radical groups" had already started.
Another senior rebel source said months of covert Turkish intelligence efforts were focusing on separating a minority of foreign militants within Hayat Tahrir al Sham from a majority of its Syrian followers, who could eventually be rehabilitated.
Precision strikes would help to handle foreign militants, whose presence has often been cited by the Syrian regime forces and Russia as the reason for an assault on Idlib as a "terrorist nest", the source said.
The National Front for Liberation, which had declared its "complete cooperation" with the Turkish effort, said it foresaw a smooth operation once logistical preparations with Turkey were concluded.
"Pulling heavy arms from the frontline is not a difficult matter as most of these weapons are deployed away from the frontline," Abdul Razzak said, adding the group's only concern was whether the Syrian regime and its allies would abide by the deal.