Five of the casualties were among Kurdish fighters in northern Iraq, known as Peshmerga.
Others were reported by the YPG, a Kurdish group in northern Syria.
Both groups have proven to be some of the most effective fighting forces on the ground against ISIS. Yet Tuesday’s airstrikes exposed the complicated tangle of Kurdish militant groups in the region, and the tough choices that the United States faces in its regional alliances in the battle against ISIS.
The five Peshmerga fighters were killed apparently in error when Turkish warplanes carried out airstrikes on nearby positions of another group that Turkey considers to be terrorists, the Kurdish Workers Party, or PKK, which is usually based in Turkey.
The strikes hit at dawn on Mount Sinjar, west of Mosul, Iraq, according to a spokesman for the Peshmerga ministry.
Nine others were injured and transferred to a nearby hospital. The Peshmerga later released a statement blaming the strikes on the presence of the PKK group, which it said it has long asked to leave the Mount Sinjar area.
“One of our Peshmerga military posts is located very close to the airstrikes and was hit by mistake,” Halgord Hikmat, spokesman for the Peshmerga ministry, told CNN.
YPG calls attack ‘cowardly’
YPG militia members were also killed in Turkish airstrikes Tuesday.
In a statement, the YPG said Turkish planes launched a “large-scale attack” on its headquarters in Mount Karachok near Syria’s border with Turkey, killing “a number of our comrades.”
A YPG spokesman said in a later statement that 20 fighters were killed and 18 others wounded. But it’s not clear if all the dead and injured were members of YPG, or People’s Defense Units.
“We as the People’s Defense Units say that this cowardly attack will not discourage our determination and our free will to fight and confront terrorism,” the YPG said.
The YPG is a key component of the Syrian Democratic Forces — backed by the United States in the fight against ISIS in Syria. Those forces have been closing in on the ISIS stronghold in Raqqa
But Turkey opposes the YPG because it fears Kurdish separatism.
Turkey says PKK was the target
Turkey’s operations Tuesday were targeting the PKK, which Ankara, the United States and the European Union consider to be a terror group.
For decades, Turkey has been facing a violent insurgency from the PKK — a banned group that first took up arms in 1984 seeking an independent state for the Kurdish minority concentrated in the country’s southeast.
Turkey has often suggested that the PKK and YPG operate closely, although the YPG denies such ties.
Tuesday’s airstrikes were not the first time that Turkish warplanes have targeted PKK positions in Iraq and Syria.
In a statement issued via Turkey’s state-run news agency, Anadolu, the Turkish General Staff said the airstrikes hit PKK targets in both countries.
It described the strikes as a “counterterrorism” operation “within the scope of the international law” to prevent the PKK from sending “terrorists, arms, ammunition, and explosives” to Turkey.