Syria's northern province of Idlib is home to the last major rebel bastion in the country, and part of it could be the next target of Russian-backed government forces.
An operation looks imminent but may be limited in scope, giving more time for a deal with Turkey, which also has forces deployed in the area.
The Syrian army, having retaken the entire area around Damascus and rebel strongholds in the south earlier this year, has sent reinforcements to the Idlib fronts.
"Tanks are going north and Russian and Syrian officials are banging the drums of war in the media, so it seems likely there will be some form of offensive," said analyst Aron Lund.
On August 15, the pro-government Al-Watan daily described the reinforcements dispatched to Idlib as the biggest since the start of the war in 2011.
The province hosts thousands of rebels who were transferred there after surrendering during previous government operations in other parts of the country.
The fighters there, including the Hayat Tahrir al-Sham jihadist group that dominates the province, have been building defensive structures across the province, training new recruits and organising drills.
The regime holds a small sliver of territory in the southeast of the province.
The government of President Bashar al-Assad has, with Russian backing, rolled back many of the losses suffered at the beginning of the war. It now controls about 60 percent of Syria and 12 out of 14 provinces.
Despite Assad's pledges to assert his authority over the entire territory, it is unclear what the immediate goals of an Idlib offensive would be.
"I think a limited operation is most likely at this stage," said Lund, a fellow with The Century Foundation.
He argued that taking on the entire province "would be a huge undertaking" and said a fully-fledged province-wide assault would "run up against Turkish resistance".
Sam Heller, from the International Crisis Group think tank, also said: "A more limited offensive to capture some peripheral sections of the rebel-held northwest seems very possible, even likely."
Experts say key targets could include the Jisr al-Shughur area in western Idlib and the adjacent farming region of Sahl al-Ghab, in the south of the province.
The region is close to Latakia province, the coastal heartland of Assad's Alawite minority which is also home to the Russian military airport of Hmeimim.
"The Russians are convinced that the drones that have targeted their airbase in Latakia are emanating from the area around Jisr al-Shughur," Heller said.
Other likely targets are areas flanking the key M5 highway that links the country's north and south, running through Idlib.
The recapture of Idlib would be the final nail in the coffin of the rebellion, whose footprint has shrunk to around 8 percent of the country, according to the Syrian Observatory for Human Rights.
But the biggest obstacle in the regime's way could be Ankara, which has forces deployed at observation posts there and supports some of the rebel forces.
Just across the border from Idlib, Turkey already hosts three million Syrian refugees and is keen to avoid a fresh influx.
The scope of the offensive and the fate of some regions could be decided in ongoing talks between Ankara and Damascus's main Russian sponsor.
"Turkey may possibly be willing to accept losses to some peripheral areas, on the condition that accepting them secures more durable Turkish control in Idlib's central and border heartlands," said Charles Lister, of the Middle East Institute.
Turkey is being asked to clamp down on Idlib's jihadists, who are mostly members of Syria's former Al-Qaeda affiliate, a strategy it has attempted to advance by uniting other rebel factions.
"Simply and brutally, the salvation of Idlib is the death of Hayat Tahrir al-Sham," said Nick Heras, of the Center for a New American Security.