Ain Issa, Syria (CNN) Pro-Turkish forces cut off the main road between the east and west of Syrian Kurdish territory Sunday, effectively cutting off the main city of Kobani.

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.

Photos: The conflict in northern Syria A car burns following a car bomb explosion in Tal Abyad, a city in northern Syria near the Turkey border, on Saturday, November 23. Hide Caption 1 of 41 Photos: The conflict in northern Syria Kurdish demonstrators hurl rocks at a Turkish military vehicle on Friday, November 8, during a joint Turkish-Russian patrol near the town of Al-Muabbadah in the northeastern part of Hassakah on the Syrian border with Turkey. Hide Caption 2 of 41 Photos: The conflict in northern Syria A man stands next to a burning motorcycle at the site of a deadly car bomb explosion in Tal Abyad, Syria, on Saturday, November 2. Turkey's defense ministry blamed the Kurdish People's Protection Units and the Kurdistan Workers Party, while a group aligned with the Kurds blamed Turkey. Hide Caption 3 of 41 Photos: The conflict in northern Syria A man inspects the site of the car bomb explosion in Tal Abyad. Hide Caption 4 of 41 Photos: The conflict in northern Syria A Turkish and Russian patrol is seen near the town of Darbasiyah, Syria, on Friday, November 1. Turkey and Russia launched patrols in northeastern Syria under a deal that halted the Turkish offensive against Syrian Kurdish fighters. Hide Caption 5 of 41 Photos: The conflict in northern Syria Turkish soldiers east of Ras al-Ain watch as a tank fires on positions held by the Syrian Democratic Forces on Monday, October 28. Hide Caption 6 of 41 Photos: The conflict in northern Syria Syrian Kurds wave flags in Qamishli as they take part in a demonstration in support of the Syrian Democratic Forces on October 28. Hide Caption 7 of 41 Photos: The conflict in northern Syria Kurdish forces withdraw from an area near the Turkish border with Syria on Sunday, October 27. Hide Caption 8 of 41 Photos: The conflict in northern Syria Displaced Syrian children sit on classroom tables at a school turned into a shelter on Thursday, October 24. Hide Caption 9 of 41 Photos: The conflict in northern Syria Russian military police began patrols on part of the Syrian border on Wednesday, October 23. Hide Caption 10 of 41 Photos: The conflict in northern Syria People angry over the US withdrawal hurl potatoes at American military vehicles as they pass through Qamishli on Monday, October 21. The image was taken from video provided by the Kurdish Hawar News Agency. Hide Caption 11 of 41 Photos: The conflict in northern Syria US military vehicles drive after pulling out of their base in the northern Syrian town of Tal Tamr on Sunday, October 20. Hide Caption 12 of 41 Photos: The conflict in northern Syria A US service member looks out of an armored vehicle as troops pull out of their base in Tal Tamr. Hide Caption 13 of 41 Photos: The conflict in northern Syria Smoke billows from a fire in Ras al-Ain, Syria, on Friday, October 18. US Vice President Mike Pence announced a day earlier that he and Turkish President Recep Tayyip Erdogan had agreed to a ceasefire halting Turkey's incursion into northern Syria. The Turkish government insisted that the agreement was not a ceasefire, but only a "pause" on operations in the region. Hide Caption 14 of 41 Photos: The conflict in northern Syria A woman reacts as a man's dead body arrives at a hospital in Ras al-Ain on October 18. Hide Caption 15 of 41 Photos: The conflict in northern Syria Displaced Syrians carry their belongings at a refugee camp north of Mosul, Iraq, on Thursday, October 17. Hide Caption 16 of 41 Photos: The conflict in northern Syria Local residents cheer as Turkish army tanks are transported on the outskirts of Akcakale, Turkey, on October 17. Hide Caption 17 of 41 Photos: The conflict in northern Syria A local resident of Ras al-Ain kisses the forehead of a member of the Turkish-backed Free Syrian Army on October 17. Hide Caption 18 of 41 Photos: The conflict in northern Syria Displaced people ride a motorcycle on the outskirts of Tal Tamr, Syria, on Wednesday, October 16. Hide Caption 19 of 41 Photos: The conflict in northern Syria People in Qamishli, Syria, attend a funeral Monday, October 14, for five fighters of the Syrian Democratic Forces. Hide Caption 20 of 41 Photos: The conflict in northern Syria A person inspects damage to a building in Akcakale, Turkey, on Sunday, October 13. The building was damaged by a mortar fired from inside Syria. Hide Caption 21 of 41 Photos: The conflict in northern Syria Some fighters of the Syrian Democratic Forces are buried in Qamishli on Saturday, October 12. Hide Caption 22 of 41 Photos: The conflict in northern Syria Smoke billows from Tal Abyad, Syria, on Friday, October 11. Hide Caption 23 of 41 Photos: The conflict in northern Syria Pro-Turkish Syrian fighters drive an armored personnel carrier across the border into Syria on October 11. Hide Caption 24 of 41 Photos: The conflict in northern Syria People drive past shops in Akcakale, Turkey, that were closed by owners who feared incoming shelling from Syria. Hide Caption 25 of 41 Photos: The conflict in northern Syria Turkish-backed fighters of the Free Syrian Army head toward Tal Abyad, Syria, on Thursday, October 10. Hide Caption 26 of 41 Photos: The conflict in northern Syria Refugees arrive in Tal Tamr, Syria, after fleeing the fighting on October 10. Hide Caption 27 of 41 Photos: The conflict in northern Syria A woman holds a baby after arriving in Tal Tamr. Hide Caption 28 of 41 Photos: The conflict in northern Syria Smoke rises from Tal Abyad, Syria, on October 10. Hide Caption 29 of 41 Photos: The conflict in northern Syria People in Akcakale, Turkey, watch smoke billow from inside Syria. Hide Caption 30 of 41 Photos: The conflict in northern Syria Turkish soldiers move into Tal Abyad. Hide Caption 31 of 41 Photos: The conflict in northern Syria Smoke rises from the Syrian city of Ras al-Ain on Wednesday, October 9. Hide Caption 32 of 41 Photos: The conflict in northern Syria Civilians flee during the bombardment on October 9. Roads were gridlocked with hundreds of fleeing families. Hide Caption 33 of 41 Photos: The conflict in northern Syria Turkish troops prepare for the operation on October 9. Hide Caption 34 of 41 Photos: The conflict in northern Syria Refugees leave their homes near the Turkey-Syria border. Hide Caption 35 of 41 Photos: The conflict in northern Syria Turkish military vehicles drive through Akcakale, Turkey, near the border. Hide Caption 36 of 41 Photos: The conflict in northern Syria Turkey launched airstrikes and artillery fire across the border on October 9. Hide Caption 37 of 41 Photos: The conflict in northern Syria Residents of Akcakale cheer as a convoy of Turkish military vehicles is driven to the Syrian border just after the offensive began. Hide Caption 38 of 41 Photos: The conflict in northern Syria "Our aim is to destroy the terror corridor which is trying to be established on our southern border and to bring peace and peace to the region," Turkish President Recep Tayyip Erdogan tweeted as he announced the start of the operation. Hide Caption 39 of 41 Photos: The conflict in northern Syria Smoke is seen in Tal Abyad, Syria, on October 9. Hide Caption 40 of 41 Photos: The conflict in northern Syria Kurdish people in Ras al-Ain, Syria, wave their group's flags as they protest against a military operation on Monday, October 7. Hide Caption 41 of 41

Yet the SDF face serious problems on other fronts, especially the besieged town of Ras Al Ain. They continued fighting Saturday, hours after Turkish officials claimed to have taken the town.

An SDF fighter at dawn in the town of Tal Tamr told CNN that there were about 400 SDF fighters inside the town, besieged by the Turkish-backed Syrian rebels. He drew a map with a ballpoint pen on a tablecloth, to show the encirclement of these forces, apart from one small corridor to the south.

130,000 people displaced

More than 130,000 people have been displaced from rural areas around Tal Abyad and Ras al-Ain, following Turkey's military offensive in the area, according to a report from the UN Office for the Coordination of Humanitarian Affairs (OCHA).

It comes after the Turkish Defense Ministry announced on Saturday that it had taken control of Ras al-Ain. Major Yousef Hamoud of the Turkish-backed Syrian National Army also told CNN Sunday that forces had "managed to fully liberate Tal Abyad and managed to drive out the terrorist gangs of PYD/PKK."

Displaced Syrians, who fled their homes in the border town of Ras al-Ain, receive humanitarian aid on October 12.

Public and private hospitals in Tal Abyad and Ras al-Ain closed down on October 11, the OCHA reported, and 33 shelters have been set up in Raqqa, Hasakeh, and Al-Tamr.

The OCHA also reported that more than 5,000 people in a shelter in Mabrouka were relocated to Areesha after Mabrouka was hit by the offensive.

The UN estimates that as many as 400,000 people may need assistance and protection in the coming period.

An earlier version incorrectly described the escapees from the Ain Issa camp. This has been corrected.