Turkey's military has launched airstrikes against Kurdistan Workers' Party (PKK) targets in northern Iraq, the state-run Anadolu news agency reported Wednesday.
The airstrikes on Tuesday night, also confirmed by Kurdish sources, came in the aftermath of a suicide bombing in Istanbul that killed 10 German tourists.
Turkish authorities are blaming the Istanbul attack on Islamic State, but the extremist group has not claimed responsibility for the bombing.
Islamic State also did not claim suicide bombings last year that left more than 140 people dead and bore the group's fingerprints.
Turkey has been accused repeatedly of taking a tougher stand against the PKK than against Islamic State, which controls large swathes of territory in Syria and Iraq and aims to seize territory around the world and impose strict Islamic law.
The PKK is battling the state for greater autonomy for the Kurdish minority, an ethnic group that has long complained of discrimination and is currently facing tough military crackdowns.
In recent weeks, however, Turkish security forces have thwarted a number of alleged bomb plots by Islamic State and hundreds linked to the Sunni militant group have been arrested this month.
"These latest incidents point to the continued presence of the ISIS network in Turkey," says Aaron Stein, a Turkey researcher with the Atlantic Council think tank, using an acronym for the extremists.
Turkey find itself in a difficult position given the simultaneous conflicts with Islamic State and its arch-nemesis the PKK - the Kurds have been the most effective fighting force on the ground pushing back the Sunni extremists, earning them aid from the United States.
"Both organizations are a serious threat to us," a senior Turkish official said recently.
He conceded that at least part of the reason that Turkey equates the PKK and Islamic State - a controversial position - is to convince a nationalist and often Islamic-leaning public of its policy.
"Otherwise I can't persuade my citizens that the fight against Daesh is legitimate fight," he said, using an acronym for Islamic State.
Ankara has been a hesitant partner in the war against Islamic State, only formally carrying out airstrikes as part of the US-led coalition fighting the group in the second half of last year.
The United States has continued to urge Turkey to do more to shut its porous border to Syria.
The Turkish military has been bombing the PKK in Iraq and Turkey since July, when a two-year ceasefire broke down.
Hundreds have died in Turkey in renewed violence over the past six months with intense military operations ongoing in the south-east.