ISTANBUL/BEIRUT (Reuters) – Turkey is luring militants away from the jihadist alliance that controls Syria’s northwestern Idlib province as a step toward implementing a deal to reduce violence there, Foreign Minister Mevlut Cavusoglu said on Tuesday.

Idlib is one of four “de-escalation” zones which foreign powers agreed to establish in opposition territory in western Syria after years of civil war. But the former al Qaeda branch which controls the province has pledged to keep fighting Syrian government forces and their allies.

The ex-Nusra Front’s stance has raised doubt about how Turkey, one of three parties to the agreement, can proceed with plans to deploy observers inside Idlib. Russia and Iran, the other two countries involved, are due to police its edges.

Cavusoglu said the first stage, already under way, was to separate “moderate rebels” from “terror organizations” – a reference to Nusra, which cut ties with al Qaeda last year, rebranded itself and now spearheads the Tahrir al-Sham jihadist alliance that dominates Idlib.

His comments endorsed remarks by a rebel source who said that efforts by foreign states were under way to encourage defections from the alliance, to break it up, isolate it and reduce its capacity to oppose any Turkish military deployment.

“With regards to Nusra, they are working to weaken it through intelligence operations,” the source told Reuters. Those could include assassinations and campaigns to undercut the group’s popular support, the source said.

The aim was to encourage jihadist fighters who are not members of al Qaeda to “melt into society”.At least two million people live in Idlib, the largest populated Syrian area held by rebels – including some nationalist Free Syrian Army factions who sometimes fought alongside jihadists.

The province’s population has ballooned as thousands of civilians and combatants have left areas seized by the Syrian army in other parts of the country, with the help of Russian jets and Iran-backed militias.

ISOLATING JIHADISTS

Turkey already controls a swathe of northern Syria east of Idlib following a military incursion in 2016. The rebel source said up to 2,000 fighters being trained by Turkish forces could deploy to Idlib, where many people have close ties to Turkey and could welcome a Turkish presence.

Turkey has called for the overthrow of President Bashar al-Assad and supported several rebel factions, but has recently worked with Iran and Russia, both strong supporters of Assad, to stem the violence in Syria’s six-year conflict.

Comparing the array of factions fighting Assad to a divided family, Cavusoglu said it was vital to avoid indiscriminate bloodshed and criticized the continued Russian and Syrian air strikes in Idlib which he said were killing civilians.

”Think of a family with four sons,“ he said in a televised interview. ”Two of them are members of the Free Syrian Army, which everybody supports, one is not related to anything and the last one is a member of a terror organization.

“What do we do? Will we bomb this family and kill them all; the mother, father and small children? We have to determine the one and separate him from the others”.

Cavusoglu said work to separate the jihadists from other factions had been “going on rapidly”, but needed meticulous application and would require broad international support.

Tahrir al-Sham, which was formed in January, has been hit in recent months by the breakaway of two of its significant fighting factions, Nour el-Din al-Zinki and Jaish al-Ahrar.

In a change of leadership announced on Sunday, Abu Mohammad al-Jolani, the head of Nusra Front, assumed command of Tahrir al-Sham after Abu Jaber al-Sheikh quit that post. Tahrir al-Sham gave no reason for the resignation, adding in a statement that al-Sheikh had been appointed head of its Shura Council.

Insurgent sources in northwest Syria say ideological divisions between the groups that form Tahrir al-Sham have been a big factor leading to the departure of some members.