Russia has virtually accused Turkey and its allies of nursing the Islamic State terrorists with continued supplies using the Syrian border town of Azaz, in Aleppo, even as Ankara vowed it will not let Aleppo fall into the hands of Kurdish forces who are battling the IS.
Turkey on Monday warned the YPG Kurdish militia that it would face the "harshest reaction" if it tried to capture Azaz, near the Turkish border.
Ankara also accused Russia, which provides air support to Syrian government forces, of an "obvious war crime" after missile attacks in northern Syria killed scores of people.
Russia's foreign ministry said on Tuesday that Ankara wants the Kurdish forces out of Azaz as it lies on a supply route used by it to support Islamic State. In fact, Moscow said it has been warned by some of its partners (meaning Washington and its allies) in the war on IS to keep off the border areas of Turkey and Syria.
"Some of our partners have literally implored us 'not to touch' a corridor which is a bit shorter than 100 kilometres on the Syrian-Turkish border around Azaz," Russian foreign ministry spokeswoman Maria Zakharova said in official comments.
"Obviously, this is aimed at ensuring continued daily supplies to Islamic State, Jabhat al-Nusra and other terrorist groups with weapons, ammunition and food from Turkey via this area, and also to allow it to serve as a passageway for terrorists," she said.
The Syrian offensive, supported by Iranian-backed Shi'ite militias as well as Russian air strikes, has brought the fighting within 25 km of Turkey's border.
On the other hand, Kurdish fighters are filling the space after the collapse of IS and Syrian rebel positions to seize ground and extend their presence along the border.
Turkey has now asked its Nato allies, including the United States, to take part in a joint ground operation in Syria, as advancing Moscow-backed government forces neared its borders, raising the possibility of direct confrontation between the Nato member and Russia.
Turkey's defence minister said its artillery had returned fire into Syria for a fourth straight day on Tuesday, targeting the Kurdish YPG militia which Ankara says is being backed by Moscow.
Washington, however, has ruled out a major offensive and a large-scale joint ground operation is unlikely as Washington is averse to sending ground forces to fight the Islamic militants.