Turkish President Tayyip Erdogan said U.S.-supplied weapons had been used against civilians by a Syrian Kurdish militia group that Ankara blames for a deadly suicide bombing, and said he would talk to President Barack Obama about it later on Friday.
U.S. support for the Syrian Kurdish PYD, which Washington considers a useful ally in the fight against Islamic State, has enraged Turkey and risks driving a wedge between the NATO allies. Turkey sees the group as a terrorist organization linked to Kurdish militants waging an insurgency on its own soil.
Erdogan and the Turkish government have said the PYD's armed wing, the YPG, was responsible for a suicide car bomb attack in the administrative heart of the capital, Ankara, on Wednesday which killed 28 people, most of them soldiers.
Erdogan said he was saddened by the West's refusal to call the PYD and YPG a terrorist group and would explain to Obama by phone how weapons provided by the United States had aided them.
"I will tell him, look at how and where those weapons you provided were fired," he told reporters in Istanbul.
"Months ago in my meeting with him (Obama), I told him the U.S. was supplying weapons. Three plane loads arrived, half of them ended up in the hands of Daesh (Islamic State), and half of them in the hands of the PYD," he said.
"Against whom were these weapons used? They were used against civilians there and caused their deaths."
He appeared to be referring to a U.S. air drop of 28 bundles of military supplies in late 2014 meant for Iraqi Kurdish fighters near the Syrian city of Kobani. Pentagon officials said at the time one had fallen into the hands of Islamic State. The Pentagon later said it had targeted the missing bundle in an air strike and destroyed it.
Turkish Foreign Minister Mevlut Cavusoglu earlier accused the United States of making conflicting statements about the Syrian Kurdish militia.
He said U.S. Secretary of State John Kerry had told him the Kurdish insurgents could not be trusted, in what Cavusoglu said was a departure from Washington's official position.
The United States has said it does not consider the YPG a terrorist group. A spokesman for the State Department said on Thursday Washington was not in a position to confirm or deny Turkey's charge the YPG was behind the Ankara bombing.
The spokesman also called on Turkey to stop its recent shelling of the YPG. The YPG's political arm has denied the group was behind the Ankara attack and said Turkey was using it to justify an escalation in fighting in northern Syria.