Istanbul - Turkey’s president announced that a Turkish military helicopter was “downed” in northern Syria Saturday during Ankara’s offensive on Syrian Kurdish militia there.

Speaking in Istanbul on Saturday, President Recep Tayyip Erdogan didn’t mention by name the Syrian Kurdish People’s Protection Units, or YPG, but said that those responsible will pay for it.

The Turkish military said in a statement that two soldiers were killed when its attack helicopter crashed and was destroyed at around 1pm local time (10am GMT).

A spokesman for the Kurdish militia, Mustafa Bali, said his fighters downed the chopper in Raju, northwest Afrin.

In a video posted online by the YPG-dominated Syrian Democratic Forces, a helicopter is seen flying over a tree-lined hill and another helicopter is captured during its crash. A helicopter is seen firing two rockets in the area as plumes of smoke from the crash rise over the trees.

After Erdogan declared “one of our helicopters was also downed,” the Turkish prime minister said that the cause of the helicopter’s crash was not yet clear and investigations were ongoing.

“We don’t have exact evidence or document to determine that it went down with any outside interference,” Binali Yildirim told reporters in the western province of Mugla.

Turkey launched a military offensive on January 20 to oust the YPG from Afrin, citing national security. Turkey considers the group a terrorist organisation and an extension of an insurgency within its own borders that has fought for Kurdish autonomy for more than three decades.

Twenty one Turkish soldiers have died since the beginning of the operation.

“We are in a war. We will have losses but we will also cause losses,” Erdogan said in Istanbul.