Erdogan to visit Russia on Tuesday

Earlier on Friday, Erdogan discussed the latest developments in Syria over the phone with his Russian counterpart Vladimir Putin.

In a phone call, Erdogan stressed that Assad regime's violations and attacks in Idlib, northwestern Syria, is causing a "major humanitarian crisis".

Erdogan also said on Friday he would discuss developments in northwestern Syria in a phone call with US President Donald Trump in the coming days.

Turkey and Russia agreed last September to turn Idlib into a de-escalation zone where acts of aggression are expressly prohibited.

The Assad regime and its allies, however, have consistently broken the terms of the cease-fire, launching frequent attacks inside the zone. 

The de-escalation zone is currently home to some 4 million civilians, including hundreds of thousands displaced in recent years by Assad regime.