Four Turkish soldiers were wounded in artillery and rocket attacks by Kurdish militants on bases in northern Syria, prompting a counter attack, Ankara said on Sunday.
Turkey's defense ministry said the attacks were carried out by the Syrian Kurdish YPG militia, which spearheads the US-allied Syrian Democratic Forces (SDF), and also the Kurdistan Workers' Party (PKK), which Turkey and Western nations deem a terrorist group.
Turkey has carried out several cross-border military incursions into northern Syria in recent years and has dozens of bases there.
The four soldiers were sent to hospital, the ministry said. "Ample response is given to the terrorists with strong attacks on targets," it added.
Earlier on Sunday Turkish President Tayyip Erdogan said "We could never be safe while there is an armed terrorist organization" in the north of Syria and Iraq.
"Hopefully in the upcoming term we will increasingly continue our efforts in this direction," he added in a speech in the southeastern city of Sanliurfa, referring to elections set for May 14.