A statement from the military wing of the Kurdistan Workers' Party, PKK, said Wednesday's attack on the premises of the aerospace and defense company TUSAS was carried out by two members of its so-called "Immortal Battalion" in response to Turkish "massacres" and other actions in Kurdish regions.
A man and a woman stormed TUSAS' premises on the outskirts of Ankara, setting off explosives and opening fire. Four TUSAS employees were killed there. The assailants arrived on the scene in a taxi that they had commandeered by killing its driver.
The assailants were also killed in a subsequent battle with security teams and more than 20 people were injured in the attack.
Turkey blamed the attack on the PKK and immediately launched a series of aerial strikes on locations and facilities suspected to be used by the militant group in northern Iraq or by its affiliates in northern Syria.
The attack on TUSAS came at a time of growing signs of a possible new attempt at dialogue to end the more than four-decade-old conflict between the PKK and Turkey's military.
Earlier this week, the leader of Turkey's far-right nationalist party that's allied with President Recep Tayyip Erdogan raised the possibility that Abdullah Ocalan, the PKK's imprisoned leader, could be granted parole if he renounces violence and disbands his organization.
Ocalan, who is serving a life sentence on a prison island off Istanbul, said in a message conveyed by his nephew on Thursday that he was ready to work for peace.
The PKK's military wing, the People's Defense Center, said, however, that the attack was not related to the latest "political agenda," insisting it was planned long before.
It said TUSAS was chosen as a target because weapons produced there "killed thousands of civilians, including children and women, in Kurdistan."
TUSAS designs, manufactures and assembles civilian and military aircraft, unmanned aerial vehicles and other defense industry and space systems. Its defense systems have been credited as key to Turkey gaining an upper hand in its fight against Kurdish militants.
On Friday, an Iraqi security official said Turkish warplanes intensified their airstrikes on sites belonging to the PKK and other loyal forces in northern Iraq's Sinjar district. The intensive bombing targeted tunnels, headquarters and military points of the Workers' Party and the Sinjar Protection Units inside the Sinjar Mountain area.
A local official and a security official said the bombings killed five Yazidis. The officials spoke on condition of anonymity in line with regulations.
The Kurdish-led Syrian Democratic Forces said Thursday that the Turkish warplanes and drones struck bakeries, a power station, oil facilities and local police checkpoints. At least 12 civilians were killed and 25 others were wounded.
The People's Defense Center statement said there were no casualties among PKK fighters in the airstrikes.
Meanwhile, police in Istanbul detained at least 35 people suspected of links to the PKK, the state-run Anadolu Agency reported.
The PKK has been fighting for autonomy in southeastern Turkey in a conflict that has killed tens of thousands of people since the 1980s. It is considered a terrorist group by Turkey and its Western allies.