Six Turkish soldiers were killed and another wounded in an attack on a Turkish military base in northern Iraq, Turkey’s defense ministry said on Saturday, AFP reported.

A Turkish military base near Hakurk in northern Iraq was attacked on Friday night by members of the PKK (Kurdistan Workers’ Party), which Ankara and its Western allies classify as a terrorist group, the ministry said.

In response to this, a military operation is underway in the region, the authorities said.

The Turkish military regularly conducts ground and air operations against PKK militants and their positions in northern Iraq, autonomous Kurdistan and the mountainous region of Sinjar.

Over the past 25 years, Turkey has established dozens of military bases in Iraqi Kurdistan to fight the group, which also has bases in the region.

The PKK, which has been waging an armed struggle against Turkish authorities since 1984, claimed responsibility for an attack on the headquarters of Turkey’s interior ministry in Ankara last October, in which two police officers were wounded.