A Turkish army helicopter was shot down by Syrian Kurdish YPG fighters near the north Syrian town of Afrin, President Tayyip Erdogan said on Saturday and the Turkish military said two soldiers on board the aircraft died.
YPG sources separately confirmed the downing of the helicopter.
"One of our helicopters was downed just recently," Erdogan said speaking to members of his AK Party (AKP) in Istanbul. "These things will happen, we are in a war... We might lose a helicopter, but they'll pay the price for this."
The Turkish military in a statement did not specify a reason for why the helicopter fell. It said two soldiers on board died and technical crews were investigating the crash.
The downed helicopter was the first officially confirmed loss of a Turkish aircraft over Syria since the start of the country's long-running civil war.
The Turkish military in another statement said three soldiers were killed and five wounded on Saturday in clashes with mainly Kurdish forces near Afrin. It said it had killed 15 militants.
Ankara launched an air and ground offensive last month against Kurdish fighters in Syria's Afrin region on its border, opening a new front in the multi-sided Syrian war.
Separately, the Turkish military in a statement said on Friday that the construction of a fifth military post near Syria's northwestern region of Idlib had begun.
Under the deal reached with Tehran and Moscow to try to reduce fighting between pro-government forces and mainly Islamist insurgents in the northwest Syria, Turkey agreed to set up 12 observation posts in Idlib and neighboring provinces.
But the "de-escalation" in violence they were supposed to monitor has collapsed. In December, the Syrian army alongside Iranian-backed militias and heavy Russian air power launched a major offensive to take territory in Idlib province.
Idlib is one of the last main strongholds of rebels opposed to President Bashar al-Assad, who have been driven from most of their bastions in Syria since Russia joined the war on the side of Assad's government in 2015. Turkey has long been one of the main allies of the anti-Assad rebels.