The move blocks the main highway – and perhaps only route – to Kobani, where US troops are based.
CNN witnessed Turkish military armored personnel carriers on the M4 highway between Tal Tamr and Ain Issa, parked by the side of the road. Further reinforcements made their way through the dust towards the dozen armored vehicles, parked 10 meters (about 30ft) from the road.
Meanwhile, a US official familiar with the situation on the ground said American forces in Syria had yet to receive a formal order to withdraw, but were preparing to do so.
The official added that the situation on the ground is deteriorating rapidly in northeast Syria, and confirmed that Turkish proxies, which the official describes as including “extremists,” have advanced along the M4 highway setting up multiple checkpoints.
He said these proxy forces were wearing SDF uniforms and killing civilians on the highway. US Forces and SDF no longer control ground lines of communication or Turkish aircraft flying overhead.
“US forces are at risk of being isolated and there is increased risk of confrontation between Turkish proxies and US forces unless Turkey halts their advance immediately,” the official said.
CNN did not observe the checkpoints, but witnessed the departure from Ain Issa of an American patrol.
The four armored vehicles left minutes before a Turkish jet flew very low over the town, “buzzing” Syrian Kurdish fighters and the American convoy.
Two US Apache helicopters then flew over the town for 15 minutes, looping what is a key base for the SDF.
While Kurdish civilians fear the Syrian rebels, some are also furious at US and Coalition forces, with whom they fought ISIS, for abandoning them. “God curse America,” said one man. “What have you done for us?”
785 people affiliated with ISIS escape
Meanwhile, Syrian Democratic Forces (SDF) spokesperson Mustafa Bali tweeted that almost all suspected ISIS militants had fled Ain Issa camp.
Kurdish authorities claim Turkey’s offensive has led to the escape of “785 people affiliated with foreign ISIS fighters” from the Ain Issa camp. The camp mainly houses internally displaced people and some ISIS family members.
According to a statement posted on the Autonomous Administration of North and East Syria Facebook page, “ISIS elements attacked the camp guards, opened the gates and escaped.”
CNN is unable to verify these claims. Kurdish officials were not immediately available to provide further details or to clarify in what capacity these ISIS militants were being held in Ain Issa camp.
An American official, expressing anger over the recent developments, told CNN that in his opinion US policy had “failed,” and that the nation and its allies “are now facing new threats at home and abroad.”
“ISIS has a second life and our geo-political allies are the ones who have the advantage,” said the official, speaking candidly in a personal capacity about the withdrawal of US troops from Syria. “Russia and (the Syrian) regime will take back all of the territory and Iran has freedom of movement across the region.”
Ankara ambitions much wider than anticipated
The arrival of Turkish forces on the M4 highway, also known as the international road, suggests the ambitions of Ankara are much wider than initially stated.
The Turkish patrol was about 30 miles into Syrian Kurdish-held territory, and the Syrian rebel checkpoints, in areas where the Turkish were not thought to have ambitions.
On Sunday during a press conference, Turkish President Recep Tayyip Erdogan said the Turkish offensive would go 30-34 kilometers (18-21 miles) into Syrian territory.
“We are not allowing the establishment of a terror state in northern Syria, and we will not in the future,” Erdogan said. “We have no interest in other countries land, however those that set eyes on our lands, we cannot close our eyes, we don’t have the luxury of showing mercy.”
On the road west along the M4 there was evidence of pro-Turkish forces.
Airstrikes had hit some checkpoints, and the SUV in which the murdered Kurdish political leader Hevrin Khalaf allegedly drove, was shot up by the side of the road – its armored glass torn out of the windows.
The fall of the main highway presents a strategic crisis for the Syrian Kurds as it cuts off the remaining main access route between their key towns to the west. It also isolates the population center of Kobani, where the US has previously used an airfield and has an observation outpost.
It also shows that the initial Turkish incursion intends to pressure – at the least – Kurdish territory over 10 miles further than the 18-mile-deep corridor suggested they would occupy.