Russian and Syrian forces have been holding joint training exercises in Syria's Latakia province for the past fortnight to prepare for fighting in neighbouring rebel-held Idlib, a security source said Wednesday.
"The joint Russian-Syrian training began two weeks ago in the north of Latakia province," a regime stronghold on the country's coast, the source told AFP.
The exercises were being conducted in an area of Latakia with similar terrain to Idlib province, which is held by a coalition of rebels known as the Army of Conquest.
"In the next stage, Idlib will become the major destination and most important target of joint Russian-Syrian military operations," the source said.
The source said Idlib was now home to the largest number of rebel movements, excluding the Islamic State group, anywhere in the country.
The Army of Conquest, which includes Al-Qaeda affiliate Al-Nusra Front, wrested control of the entire province in northwestern Syria earlier this year, dealing a serious strategic and psychological blow to the regime.
Staunch government ally Moscow began an aerial bombing campaign in support of regime forces on September 30, saying it was targeting ISIS and other extremist groups.
But rebels from other groups accuse Russia of focusing its firepower more on moderate and Islamist opposition fighters than ISIS.