(Bloomberg) -- Turkey’s President Recep Tayyip Erdogan warned Syria to end its siege of two Turkish military outposts, and issued an oblique threat of retaliation against its Russian backers.

Relations between Ankara and Moscow have been strained since Syrian troops killed seven Turkish soldiers and a civilian on Monday in northwestern Idlib province, where Syria’s government, with Russian air support, is trying to vanquish onetime al-Qaeda affiliates and Turkey-backed rebels.

On Wednesday, Erdogan told Syria it has to end its siege this month or risk a harsh reprisal for attacks “from the air or the ground” -- a reference to strikes by Russian warplanes and ground attacks by Syrian soldiers and allied forces.

“We are hoping for the withdrawal of the regime from our observation points in February,” he said. “If they don’t, Turkey will be forced to do so itself.”

Earlier this week, Erdogan urged Russia to stay out of the fray when the Turkish military retaliated for the deadly attack against its forces. The fighting in Idlib is testing the marriage of convenience betwen Turkey and Russia in Syria, where the two powers have carved up spheres of influence.

Erdogan also trained his ire at agreements with the U.S. and Russia to keep Syrian Kurdish forces away from the Turkish border, saying these pacts aren’t “really implemented” and that his country has the right to conduct cross-border operations against “terrorists” in Syria under a 1998 security agreement with Damascus. Erdogan considers the Kurdish separatists a threat to its territorial integrity because of their link to Kurdish separatists in Turkey.

“The developments in Syria has forced us to amend our security strategy both in Idlib and along our border line,” Erdogan said.

(Updates with Erdogan comments from third paragraph.)

To contact the reporters on this story: Selcan Hacaoglu in Ankara at shacaoglu@bloomberg.net;Firat Kozok in Ankara at fkozok@bloomberg.net

To contact the editors responsible for this story: Onur Ant at oant@bloomberg.net, Amy Teibel

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