The two perpetrators of Sunday’s Ankara bombing entered Turkey through Syria, Turkish Foreign Minister Hakan Fidan said today.

On Sunday, two attackers detonated a bomb near government buildings in Ankara, killing themselves and injuring two police officers.

The Kurdistan Workers’ Party (PKK), which is outlawed in Turkey, claimed responsibility for the attack. Following the attacks, Turkey carried out airstrikes against Kurdish targets in northern Iraq.

Fidan stressed today that as part of Turkey’s response to Sunday’s attack, any infrastructure and energy facilities in Iraq and Syria controlled by the PKK and the People’s Protection Units (YPG) are legitimate military targets.

“We advise third parties to stay away from facilities controlled by the PKK and the YPG. The response of our armed forces to the attack will be particularly precise,” said the head of Turkish diplomacy.

Ankara describes the YPG, which it says is the Syrian arm of the Kurdish PKK rebels, as a “terrorist” organization.