A U.S. delegation began negotiations with Turkish officials on Manbij, northern Syria on Friday, Turkey's Foreign Ministry spokesman said.
The northern city of Manbij is held by the People's Protection Units (YPG) Kurdish militant, a group which is the offshoot of militant Kurdistan Workers' Party (PKK.)
The PKK, which has waged a decades-long armed conflict in Turkey, is proscribed as a terror organisation by Ankara and its Western allies.
The US has a military presence in Manbij and has provided military support to the YPG, causing anger among Turkish officials.
After Turkey launched a cross-border operation against the YPG in the western enclave of Afrin in January, President Recep Tayyip Erdoğan threatened to take the offensive to Manbij.
Turkey and the U.S. have established a mechanism to address separate issues in working groups, including stabilization of Manbij and to prevent any undesirable clashes, following the visit of former U.S. Secretary of State Rex Tillerson to capital Ankara in February.
“The second part of this meeting is being held today. We are hosting the U.S. delegation,” Hami Aksoy told reporters in Ankara during a news conference.
The first meeting of the working group on Syria was held on March 8-9 in Washington.
U.S. BILL ON F-35 PROGRAM
Aksoy said a bill passed by the U.S. Senate Committee on Thursday, which includes a measure to bar Turkey from purchasing F-35 jets, was aimed at making Ankara give up on S-400 procurement and releasing American Pastor Andrew Brunson -- who is facing terror charges in Turkey.
"We have fulfilled our responsibilities in the F-35 program. Everyone’s responsibility has been ascertained in the framework of the signed deal and we expect them to be accomplished,” Aksoy said.
“We will have to respond to these kinds of moves,” he warned.
Last December, Turkey announced it had concluded an agreement with Russia for the purchase of two S-400 systems by early 2020.
Mitchell, the U.S. state department official, had claimed that Turkey could face U.S. sanctions if it went ahead with plans to buy the Russian missile systems and the purchase may "adversely impact Turkey’s participation in the F-35 program".
The first delivery of U.S.-made F-35 warplanes to Turkey is slated for June 21, after Ankara placed an order for two aircraft of the projected fleet of 100 in 2014.
