The United States military on Monday evacuated two observation posts in the Syrian cities of Ras al-Ain and Tell Abiad, Sputnik news agency reported.
This came hours after Turkish President Recep Tayyip Erdogan said that Ankara would kick off a military air and ground operation in Syria in the coming days.
The White House had previously announced that the US will not support "or be involved in" the military operation by Turkey in northeast Syria.
"Turkey will soon be moving forward with its long-planned operation into Northern Syria. The United States Armed Forces will not support or be involved in the operation, and United States forces, having defeated the ISIS territorial 'Caliphate,' will no longer be in the immediate area," White House Press Secretary Stephe Grisham said in a statement cited by The Hill.
More than 1,000 US troops are currently deployed in northeastern Syria, where they work closely with the Kurdish YPG, which leads the Syrian Democratic Forces in the region. The Kurds have proven to be among Washington's most effective allies in the fight against the Islamic State (ISIS) that has its stronghold in northern Syria.
Erdogan has repeatedly expressed frustration with Washington's close alliance with the Kurds along his country's border with Syria, linking them to the Kurdistan Workers' Party (PKK), which is designated a terrorist orgsation in Turkey. Washington also labels the PKK a terrorist group, but not the YPG.
The US, in an effort to reduce tensions in the region, has been working on establishing a safe zone along the border. However, the plans have faltered, and the Turkish President in recent days has warned that Ankara will soon be launching a military operation across the border, as soon as within the next couple of days.
Grisham, in her statement, added that the US will not be holding any more ISIS fighters, and that "Turkey will now be responsible for all ISIS fighters in the area captured over the past two years in the wake of the defeat of the territorial 'Caliphate' by the United States."
( With inputs from ANI )