The U.S.-backed Syrian Democratic Forces (SDF) see a "big possibility of open, fierce confrontation" with the Turkish army in northwestern Syria that would undermine the assault on Islamic State (IS) militants at Raqqa, a senior SDF official said on Thursday.
Naser Haj Mansour, an adviser to the SDF, told Reuters the SDF had taken a decision to confront Turkish forces "if they try to go beyond the known lines" in the areas near Aleppo where the sides exchanged fire on Wednesday.
Turkey has recently deployed reinforcements into the area, according to Turkey-backed rebel groups, prompting SDF concern that Ankara is planning to attack nearby areas under SDF control including the predominantly Kurdish Afrin area.
The SDF is an alliance of Kurdish and Arab groups spearheaded by the YPG militia which Turkey views as an extension of the Kurdistan Workers Party (PKK), which has waged a three-decade insurgency in Turkey.
Mansour said an attack on SDF-controlled areas would "do great harm" to the U.S.-backed Raqqa assault by drawing some SDF fighters away from front lines.
The Turkish military said on Wednesday it had fired artillery at YPG positions south of the town of Azaz in what it said was a response to the YPG's targeting of Turkey-backed rebels. Mansour said the SDF had responded to Turkish shelling.
Asked about the chances of greater confrontation between the SDF and Turkish forces in the area north of Aleppo, Mansour said: "Certainly there is a big possibility of open and fierce confrontations in this area, particularly given that the SDF is equipped and prepared."
He added that the SDF had decided to confront Turkish forces "if they try to go beyond the known lines".
On Thursday, Turkey's deputy prime minister, Numan Kurtulmus, said it would retaliate against any cross-border gunfire from the YPG and not remain silent in the face of anti-Turkey activities by terrorist groups abroad.
Kurtulmus also reiterated Ankara's opposition to the U.S. arming of YPG combatants and said that U.S. officials would understand that this was the "wrong path".