The Syrian government said on Thursday that an agreement between Turkey and the United States over northeastern Syria represented a "blatant attack" on Syria's sovereignty and territorial unity and a "dangerous escalation".
The agreement setting up a joint operation center to manage a strip of territory at the Turkish border showed "American-Turkish partnership in the aggression against Syria", state news agency SANA cited a foreign ministry source as saying.
The U.S.-Turkish "aggression" represented "a dangerous escalation and a threat to peace and stability in the area".
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After three days of talks in Ankara, the two countries reached an agreement on Wednesday. They said the safe zone on Syria's northeast border with Turkey should be a "peace corridor," and that every effort would be made so that Syrians displaced by war can return to their country.
Turkey and the United States, allies in NATO, have been deadlocked for months over the scope and command of the zone, given the presence of Kurdish YPG militia that fought alongside U.S. forces against Islamic State militants, but which Ankara sees as terrorists who pose a grave security threat.