The overnight attacks came after a lull in Turkish air strikes following the shooting down of a Russian warplane elsewhere in Syria last weekend.
The air strikes destroyed 19 targets including ammunition depots, shelters and gun positions, the armed forces said in a statement without specifying when the raids were conducted. The raids began at midnight, state-run Anadolu news agency said.
Seven YPG fighter and two civilians were killed in the strikes, according to the Syrian Observatory for Human Rights, a UK-based group that monitors the war in Syria.
Turkey had halted air strikes as Russia worked on its air defense system in the wake of the shooting down by Syrian rebels of a Russian warplane in Idlib province on February 3, Turkey’s Hurriyet newspaper reported.
Ankara launched an air and ground offensive in Afrin on January 20 against the YPG, which it views as a terrorist group and an extension of the Kurdistan Workers Party (PKK) that has waged a three-decade insurgency on Turkish soil.
Turkey’s President Tayyip Erdogan and Russian President Vladimir Putin spoke by telephone on Thursday and agreed to strengthen military and security service coordination in Syria, according to the Kremlin.
The YPG and its allies have set up three autonomous cantons in the north, including Afrin, since the Syrian conflict began in 2011.
Their territory has expanded since they joined forces with the US to fight Daesh militants — although Washington opposes their autonomy plans, as does Syrian President Bashar Assad’s government.
US support for the Kurdish-led forces has infuriated Turkey, which views growing Kurdish power as a security threat along its frontier.