Turkish President Recep Tayyip Erdogan said on Wednesday a military operation by his forces to push back a Syrian government offensive against rebels in northwest Syria was now "a matter of time" after talks with Russia failed to halt the assault.
Turkish troops have already massed inside the Idlib region and more were heading to the border area, bringing NATO member Turkey and Russian-backed Syria close to the brink of direct confrontation.
The Kremlin, which has supported Syrian President Bashar Assad's push with airstrikes, said a clash between Turkish and Syrian forces would be a "worst-case scenario" and Russia would work to prevent the situation from worsening.