"Turkey will soon be moving forward with its long-planned operation into northern Syria. The US Armed Forces will not support or be involved in the operation," said White House Press Secretary Stephanie Grisham in a statement released on Sunday night.
"US forces, having defeated the IS territorial 'Caliphate', will no longer be in the immediate area," the press secretary added, without further elaboration.
Anonymous officials inside the US administration have indicated that the 100 to 150 American military personnel deployed to that area would be pulled back in advance of any Turkish operation but that they would not be completely withdrawn from Syria, Xinhua news agency quoted the New York Times as saying on Sunday night.
Grisham's statement also noted that Turkey will be "responsible" for all the Islamic State (IS) fighters in the area captured over the past two years, while blaming France, Germany, and other European nations, where some fighters originated, for refusing to take them back.
The statement followed President Donald Trump's phone call with his Turkish counterpart Recep Tayyip Erdogan earlier on Sunday.
According to a readout provided by the Turkish presidency, the two leaders exchanged views on the proposed safe zone to be established in Syria, with Erdogan complaining to Trump about US military and security "bureaucracy".
Turkey is determined to continue to fight the IS in Syria and take all necessary measures to prevent such a problem in the region from happening again, Erdogan added.
The phone call came a day after the Turkish President unleashed his strongest warning yet, threatening to launch a military operation against the US-backed Kurdish militia groups in northeastern Syria, a rhetoric that has put the latter on high alert.
On August 7, Turkish and US officials agreed to set up the safe zone and develop a "peace corridor" in northern Syria which would address Ankara's security concerns about the Kurdish faction that controls the territory.
However, Ankara has been dissatisfied for delays in withdrawing the People's Protection Units (YPG), which it sees as the Syrian branch of the outlawed Kurdistan Workers' Party (PKK), while the US continues arms support to the Kurdish fighters.
Turkey also wants to set up military bases in the planned safe zone.
( With inputs from IANS )