US observation posts 'in place' on Syria-Turkey border
"At the direction of Secretary (James) Mattis, the US established observation posts in the northeast Syria border region to address the security concerns of our NATO ally Turkey," Department of Defence spokesman Rob Manning said.
Mattis said in November that the US military was in the process of installing the observation posts on the border with Turkey.
The measure was aimed at curbing tensions between the People's Protection Units (YPG) and Turkey, who consider the Kurdish militia force as a terrorist force.
The YPG make up a major component of the Syrian Democratic Forces (SDF) who have spearheaded the international fight against the Islamic State (IS) group.
"We take Turkish security concerns seriously and we are committed to coordinating our efforts with Turkey to bring stability to northeastern Syria," Manning added.
The Turkish army has launched military operations against IS in Syria and Kurdish militias since 2016.
More recently, Ankara has shelled SDF positions close to the border, leading to the suspension of their operations against IS for several days, to the embarrassment of Washington.
Turkey however has asked Washington to scrap the posts and called for an end to cooperation with the YPG.
Syria's long-oppressed Kurdish minority has established a semi-autonomous region in the north of the war-torn country.