At least two Turkish police officers have been killed and five others injured in a car bomb attack blamed on militants of the Kurdistan Workers’ Party (PKK) in the country’s southeast, security sources say.

Turkish security officials said the PKK militants blew up a car bomb near a police checkpoint in the Sirnak Province early on Sunday.

Following the attack, the Turkish air force targeted PKK’s positions in a mountainous area in Sirnak, killing two militants.

The new developments came a day after the North Atlantic Treaty Organization (NATO) voiced support for Ankara’s military campaign against the Kurdish militants.

“We believe that we all have the right to defend ourselves specifically against terrorism and terrorist groups,” said NATO’s Supreme Allied Commander Europe Gen. Philip M. Breedlove in Istanbul, adding, “So we stand with our Turkish brothers in this respect.”

The PKK has been fighting for an autonomous Kurdish region inside Turkey since the 1980s. The conflict has left tens of thousands of people dead.​

There has been renewed conflict between the PKK and Turkish security forces since July when Turkey began launching airstrikes against purported Daesh targets in Syria as well as PKK positions in Iraq after a Daesh bomb attack left 32 people dead in the southeastern Turkish town of Suruc on July 20.

A shaky ceasefire between Anakara and the PKK that had stood since 2013 was declared as null following the Turkish military campaign.