ISTANBUL (Reuters) – Turkish warplanes struck Kurdish militant targets in various regions of northern Iraq on Sunday night in response to an increase in militant attacks on Turkish army bases, the Defence Ministry said.

“The Claw-Eagle Operation has started. Our planes are bringing the caves down on the terrorists’ heads,” the Turkish Defence Ministry said on Twitter.

Turkey regularly targets Kurdistan Workers Party (PKK) militants, both in Turkey’s mainly Kurdish southeast and in northern Iraq, where the group is based.

A security source told Reuters the warplanes took off from various air bases in Turkey, notably in the southeastern cities of Diyarbakir and Malatya.

The defence ministry subsequently said the air operation targeted the PKK in the region of its stronghold at Qandil, near the Iranian border, as well as the areas of Sinjar, Zap, Avasin-Basyan and Hakurk.

“The PKK and other terrorist elements are threatening the security of our people and borders with attacks increasing every day on the areas of our outposts and bases,” it said.

The PKK, designated as a terrorist group by Turkey, the United States and European Union, took up arms against the Turkish state in 1984. More than 40,000 people have been killed in the conflict, focused in southeast Turkey.

While Turkish warplanes frequently target PKK targets in northern Iraq, Turkey has also warned in recent years of a potential ground offensive targeting the PKK bases in the Qandil mountains.