US military officials have arrived in Ankara for meetings aimed at preventing Turkey from carrying out an offensive against Washington’s Kurdish allies in northern Syria.

The high-level meetings have been characterised by US officials as a last ditch effort to dissuade Turkey from launching a unilateral attack, which the Trump administration has warned will harm the fight against Isis.

Turkey is pushing to establish a “safe zone” inside Syria that would be empty of fighters belonging to the Kurdish-led Syrian Democratic Forces (SDF), which it considers a terror group.

On Sunday, Turkish president Recep Tayyip Erdogan repeated a threat to cross into Syria without the approval of the US if Turkey’s conditions for a safe zone are not implemented.

"We entered Afrin, Jarablus, and Al-Bab. Now we will enter the east of the Euphrates," Mr Erdogan said on Sunday, referring to previous incursions into Syria. “We can only be patient for so long.”

Timeline of the Isis caliphate Show all 19 1 /19 Timeline of the Isis caliphate Timeline of the Isis caliphate ISIS began as a group by the merging of extremist organisations ISI and al-Nusra in 2013. Following clashes, Syrian rebels captured the ISIS headquarters in Aleppo in January 2014 (pictured) AFP/Getty Timeline of the Isis caliphate Abu Bakr Al-Baghdadi declared the creation of a caliphate in Mosul on 27 June 2014 Timeline of the Isis caliphate Isis conquered the Kurdish towns of Sinjar and Zumar in August 2014, forcing thousands of civilians to flee their homes. Pictured are a group of Yazidi Kurds who have fled Rex Timeline of the Isis caliphate On September 2 2014 Isis released a video depicting the beheading of US journalist Steven Sotloff. On September 13 they released another video showing the execution of British aid worker David Haines Timeline of the Isis caliphate The US launched its first airstrikes against Isis in Syria on 23 September 2014. Here Lt Gen William C Mayville Jnr speaks about the bombing campaign in the wake of the first strikes Getty Timeline of the Isis caliphate Isis militants sit atop a hill planted with their flag in the Syrian town of Kobani on 6 October 2014. They had been advancing on Kobani since mid-September and by now was in control of the city’s entrance and exit points AFP/Getty Timeline of the Isis caliphate Residents of the border village of Alizar keep guard day and night as they wait in fear of mortar fire from Isis who have occupied the nearby city of Kobani Getty Timeline of the Isis caliphate Smoke rises following a US airstrike on Kobani, 28 October 2014 AFP/Getty Timeline of the Isis caliphate YPG fighters raise a flag as they reclaim Kobani on 26 January 2015 VOA Timeline of the Isis caliphate Isis seized the ancient Syrian city of Palmyra on 20 May 2015. This image show the city from above days after its capture by Isis Getty Timeline of the Isis caliphate Kurdish forces are stationed on a hill above the town of Sinjar as smoke rises following US airstrikes on 12 November 2015 AFP/Getty Timeline of the Isis caliphate Kurdish forces enter Sinjar after seizing it from Isis control on 13 November 2015 AFP/Getty Timeline of the Isis caliphate Iraqi government forces make the victory sign as they retake the city of Fallujah from ISIS on 26 June 2016 Getty Timeline of the Isis caliphate Iraqi forces battle with Isis for the city of Mosul on 30 June 2017 AFP/Getty Timeline of the Isis caliphate Members of the Iraqi federal police raise flags in Mosul on 8 July 2017. On the following day, Iraqi prime minister Haider Al Abadi declares victory over Isis in Mosul Getty Timeline of the Isis caliphate Members of Syrian Democratic Forces celebrate in Al-Naim square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign Getty Timeline of the Isis caliphate Female fighters of the Syrian Democratic Forces celebrate in Al-Naim Square after taking back the city of Raqqa from Isis. US-backed Syrian forces declare victory over Isis in Raqqa on 20 October 2017 after a four-month long campaign AFP/Getty Timeline of the Isis caliphate Trucks full of women and children arrive from the last Isis-held areas in Deir ez-Zor, Syria in January 2019 They were among the last civilians to be living in the ISIS caliphate, by this time reduced to just two small villages in Syria’s Deir ez-Zor Richard Hall/The Independent Timeline of the Isis caliphate Zikia Ibrahim, 28, with her two-year-old son and 8-month-old daughter, after fleeing the Isis caliphate, on Saturday 26 January 2019 Richard Hall/The Independent

The US and Turkey have been at odds for months over the conditions for the safe zone. Tensions between the two Nato allies centre on a fundamental disagreement over the SDF, which controls the area on the Syrian side, from the Euphrates River to the Iraqi border.

The SDF, backed by US airpower and technical support, recaptured swathes of Syria’s northeast from Isis. The militia’s largest contingent is a Kurdish militia called the People’s Protection Units (YPG). While the US considers the YPG an ally, Turkey views it as a terror organisation and a branch of the outlawed Kurdistan Workers’ Party, which has fought the Turkish state for decades.

US Syria envoy, James Jeffrey, said last week that Washington is “committed to those who have fought with us not being attacked and not being harmed by anyone. The president made that clear publicly.”

Turkey wants its troops to control a 19-25 mile-deep zone inside Syria, while the US is arguing for a much smaller zone. But the SDF argues a unilateral incursion by Turkey would be seen as an occupation, and would be met with force.

“If the Turkish state does not choose the dialogue for a solution, we will be prepared for war,” SDF commander Newroz Ahmed said on Monday.

“If an attack is launched on any region, this attack will not be limited to this region. Rather, the long border with the Turkish state will become a region of war,” she added.

The Kurdish-led administration that controls the area said a Turkish attack would risk a resurgence of Isis, just months after the caliphate was defeated.

"These threats pose a danger on the area and on a peaceful solution in Syria, and any Turkish aggression on the area will open the way for the return of Daesh [Isis], and that aggression will also contribute to the widening of the circle of Turkish occupation in Syria," it said in a statement.

The US has tried to act as a mediator between its two allies, but Ankara has grown frustrated with the Trump administration for stalling the plans for a safe zone. After initially refusing any Turkish role in the proposed safe zone, analysts say the SDF may be forced to accept a joint US-Turkey operation.

"The US team, after several months of stalling Turkey, now believes that the only thing that will keep the Turkish army from invading is to allow Turkish military units to patrol northern and eastern Syria with the Coalition," Nicholas Heras, a fellow at the Centre for a New American Security think thank, told The Indepdendent.

"The feeling on the US side is that if they give Erdogan the 'win' of forcing a Turkish military presence in some areas that are east of the Euphrates, in chaperoned patrols with the US and perhaps French forces, then the threat of further Turkish military action can be averted. The US is not asking the SDF if it accepts a Turkish military presence, it is telling the SDF this is a fait accompli. In effect, the Americans are telling the SDF that a limited Turkish military presence in some areas of the Euphrates, is the only thing that will ward off Turkey from destroying them," he said.

Turkey’s defence ministry said later on Monday that "today's part of negotiations with the US military officials on the planned establishment of the Safe Zone in the north of Syria has been completed.