Citing anonymous U.S. officials, the report said Washington sees "mounting evidence" that a Turkish operation is imminent.
"It's a perfect storm, it's really ugly. There may just be no choice but to leave," one official was cited as saying.
For a long time, Turkish officials have been expressing that Ankara will not allow the presence of the PKK-affiliated People's Protection Units (YPG) alongside its borders. Large deployments have been made to the region by the Turkish army in recent months, signaling that an offensive is on the horizon.
Another source said officials have grown alarmed that Turkey's move might come suddenly and can catch U.S. forces off guard as any warning could come less than 48 hours before Ankara takes any action.
"It seems more and more likely based on the actions they are taking in southern Turkey."
On Aug. 7, Turkish and U.S. military officials agreed to set up a safe zone and develop a peace corridor running from the Euphrates River to the Iraqi border to facilitate the return of displaced Syrians currently living in Turkey to their home country and provide security for Turkish border settlements and military outposts.
The agreement also envisaged setting up necessary security measures to address Turkey's security concerns, including clearing the zone of the YPG, a group the U.S. has sometimes allied with, despite Turkey's objections.
President Recep Tayyip Erdoğan and Turkish officials have repeatedly warned the U.S. in the past few weeks that the joint work on the proposed safe zone was not "yielding results," and that any further attempts to stall the progress would result in Ankara taking action on its own.
Last December, Turkey decided to postpone its operation into YPG-held areas in Syria after U.S. President Donald Trump decided that Washington would withdraw its troops from Syria. The withdrawal decision was quickly interpreted as an intention by the U.S. to halt support for the YPG.
The YPG and its umbrella group the Syrian Democratic Forces (SDF) have been a thorny issue between Turkey and the U.S. in the past years as Washington continues to treat them as allies in their fight against Daesh and supplies heavy weaponry to them, despite calls and protests from Turkey.
