The Syrian Democratic Forces (SDF) warned on Thursday that there was a “major risk” of a possible “open and fierce clashes” with Turkish forces in northwest Syria.

Nasser Haj Mansour, an adviser to the SDF, made his remarks to Reuters in wake of an exchange of fire that took place there on Wednesday.

He added that 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 shooting took place.

Turkey has recently deployed reinforcements into the area, according to Turkey-backed rebel groups.

Mansour said an attack on SDF-controlled areas would “do great harm” to the US-backed Raqqa assault by drawing some SDF fighters away from front lines.

The assault is aimed at driving ISIS out of the Syrian city.

On Thursday, Turkey’s deputy Prime Minister, Numan Kurtulmus, said it would retaliate against any cross-border gunfire from the People’s Protection Units (YPG) and not remain silent in the face of anti-Turkey activities by terrorist groups abroad.

Kurtulmus also reiterated Ankara’s opposition to the US arming of YPG combatants and said that US officials would understand that this was the “wrong path”.

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.