US Secretary of State Rex Tillerson and Turkish President Recep Tayyip Erdogan have had a meeting as relations between the two NATO partners have ruptured in the wake of Ankara’s ongoing cross-border offensive in Syria’s northwestern region of Afrin against the Kurdish People’s Protection Units (YPG).

A Turkish presidential source, speaking on condition of anonymity, said the top US diplomat and the Turkish leader sought ways to improve strained ties during their Thursday meeting in Ankara, which lasted for more than three hours behind closed doors.

The source noted that Erdogan conveyed his priorities and expectations on Syria, and also discussed Iraq, regional developments and the fight against terror with the US secretary of state.

Moreover, a US State Department spokesman travelling with Tillerson said the top US diplomat and Turkey had a “productive and open” talk.

“The two engaged in a productive and open conversation about a mutually beneficial way forward in the US-Turkey relationship,” he said.

Ahead of the meeting, Turkish Defense Minister Nurettin Canikli told reporters at a news briefing in the Belgian Capital city of Brussels that Ankara expects Washington to expel the YPG from the US-backed alliance of Arab and Kurdish militants, known as the so-called Syrian Democratic Forces (SDF).

This is while US officials regard the YPG as the most effective fighting force against the Daesh Takfiri terrorist group in northern Syria, and have substantially increased their weaponry and technology support to the terrorist group.

The controversy over a possible Syria border force first started on January 14 when a report emerged on Reuters saying that the military coalition led by the United States in Syria was planning to set up a large border force of up to 30,000 personnel with the aid of its militia allies.

The Syrian government has already condemned the “brutal Turkish aggression” against Afrin, rejecting Ankara’s claim about having informed Damascus of the operation.