Mustafa and Ines were helping their parents load the van once again to flee advancing Syrian troops, when bombardment hit the area and sewed panic on the street.

A military offensive on an opposition-controlled region of northwestern Syria has created one of the worst catastrophes for civilians in the country's long-running war, sending hundreds of thousands of people fleeing, many of them sleeping in open fields and under trees in freezing temperatures.

The military campaign in Idlib province and the nearby Aleppo countryside has also killed hundreds of civilians, and a bitter winter has compounded the pain.

Russian President Vladimir Putin and Turkish leader Recep Tayyip Erdogan have discussed de-escalation of the Syrian crisis, the Kremlin said Wednesday, adding that Russian-Turkish agreements should be implemented in full.

Throughout Syria's civil war, Maad al-Khalaf helped other Syrians find shelter in the opposition enclave in the northwest as they fled government military advances around the country. Now he's the one in need of refuge as a swift offensive overwhelmed his home village.

He joined hundreds of thousands in Idlib province scrambling to escape the widening, multi-front assault by President Bashar Assad's forces, squeezing into whatever structures they can find in a shrinking territory.

Turkey threatened on Saturday to respond if any of its military outposts in Syria's last opposition bastion of Idlib came under attack, a day after officials said three of them had been encircled by forces loyal to Damascus. 

Israeli air strikes killed 23 Syrian and foreign fighters in Syria Thursday, a monitor said, the latest in a spate of raids Israel has said targeted an Iranian presence on its doorstep.

Syrian regime forces Wednesday pressed on with their offensive in the northwest that has displaced half a million people, despite heightened tensions with Turkey.

Turkish President Recep Tayyip Erdogan urged Syria on Wednesday to withdraw its troops from its military observation posts in northwestern Idlib province where clashes have intensified in recent days. 

A Russian-backed Syrian government offensive against the country's last rebel enclave has displaced more than half a million people in two months, the United Nations said Tuesday.

Turkey warned Russia not to get involved as it retaliated against Syrian government forces for killing four of its soldiers in northwest Syria on Monday.