The Turkish Armed Forces (TSK) hit targets of the PKK's Syrian offshoot, the Democratic Union Party (PYD) and its armed wing, the People's Protection Units (YPG), in northern Syria's Afrin region late Tuesday.
According to the military, the PYD/YPG terrorists shelled Turkish territory and opened heavy machine gun fire at 9:00 p.m. The attack prompted immediate retaliation by the military.
"The detected targets were neutralized," the military said in a statement, adding that it fired back within the boundaries of international law.
Turkish forces said would strike back for as long as cross-border shelling from the terrorists-held territory continued.
President Recep Tayyip Erdoğan said earlier in June that Turkey could launch a new cross-border operation if the PKK terrorist organization's offshoots in northern Syria attacked the country.
The PKK has targeted security forces and civilians in the region for decades. The terrorist organization has killed thousands of people since it was established in the early 1980s.
Ankara considers the YPG to be a terror group and the Syrian offshoot of the PKK, which is listed as a terrorist organization by the U.S., Turkey and the EU.
Turkey argues that there is no difference between the YPG and the PKK, as they share the same leadership, ideology and organizational links.