The U.S. has warned Assad and Russian Federation against launching an assault and threatened to retaliate if regime forces use chemical weapons.
The United Nations and non-governmental organizations have repeatedly warned that such an offensive would unleash a "bloodbath" and "humanitarian catastrophe" in Idlib, which is home to three million people.
Turkey's strategy in the opposition areas has been complicated by the presence of radical fighters. "But together with Russian Federation, we will put our efforts into clearing those territories of radical elements".
He said the nature of the demilitarized zone and how it would be implemented are not yet clear.
"Russia and Turkey will both have coordinated patrol activities on both sides of the border at the demilitarized zone", Erdogan said. Heavy weapons, tanks, guns, and more will be banned from the area.
Putin also said Russia's main worry is attacks on its military bases in Syria, which are sporadically hit by Turkey-backed rebels.
For Russia, foreign fighters in Idlib are a big concern.
Putin and Erdogan sat down for talks Monday afternoon.
This approach, Putin said, is supported by Syrian President Bashar al-Assad. But he needs Russian air support and pro-Iranian militias to back him.
But since then, government troops have made a fierce comeback and recaptured almost two-thirds of the country, bolstered by Syrian and Russian warplanes. Despite coming under nearly non-stop bombardment for several years, the area is still home to some 3 million Syrians, around 60,000 of whom are believed to be rebel fighters.
Activists had said that the Nusra Front, otherwise known as Hayat Tahrir al-Sham, Arabic for the Levant Liberation Committee (LLC), rounded up and killed tens of the reconciliation advocates in Idlib.
He added the formula that was agreed upon by the leaders of Turkey and Russian Federation would only postpone the confrontation between the Syrian army and the rebels and would give the Turkish side time to deal with the issue of the ultra-radical rebels in Idlib.
Together with adjoining territory north of Aleppo, Idlib forms the last opposition foothold in Syria.
The Turkish president added: "Our solidarity on regional issues will give hope to the region".
Two days after the attack on the hospital in Hama, a strike hit and damaged an underground hospital on the outskirts of Hass in Idlib, according to the Observatory.