Turkish President Tayyip Erdogan says he will not allow Kurdish groups to "seize" control of northern Syria.
Erdogan, in a speech in southeast Turkey on October 24, denounced the merging of the Syrian town of Tel Abyad last week into an autonomous political structure created by the Kurds.
"All they want is to seize northern Syria entirely," Erdogan said. "We will under no circumstances allow northern Syria to become a victim of their scheming."
Turkey is alarmed by territorial gains made by the Kurds in Syria, which it fears could stir separatism among its own Kurdish minority.
Tel Abyad, on the border with Turkey, was captured in June from Islamic State militants by the Kurdish People's Protection Units (YPG).
Turkey is wary of the YPG, which is closely linked to the banned Kurdistan Workers Party (PKK).