Syrian Arab militiamen leading the Turkish attack on Afrin in northern Syria are threatening to massacre its Kurdish population unless they convert to the variant of Islam espoused by Isis and al-Qaeda. In the past such demands have preceded the mass killings of sectarian and ethnic minorities in both Syria and Iraq.

In one video a militia fighter flanked by others describes the Kurds as “infidels” and issues a stark warning, saying "by Allah, if you repent and come back to Allah, then know that you are our brothers. But if you refuse, then we see that your heads are ripe, and that it's time for us to pluck them." Though the Kurds in Afrin are Sunni Muslims, Isis and al-Qaeda traditionally punish those who fail to subscribe to their beliefs as heretics deserving death.

“The video is 100 per cent authentic,” said Rami Abdulrahman, who heads the Syrian Observatory for Human Rights which released it, in an interview with The Independent. He adds that he is very concerned about the fate of some Yazidi villages in Afrin captured by the advancing Turkish forces, saying he has seen videos taken by the militiamen themselves in one of which “an elderly Yazidi man is questioned by them, asking him how many times he prays a day.”

Such interrogations of Yazidis by Isis to prove that they were not Muslims often preceded the killings, rapes and the taking of Yazidi women as sex slaves when Isis seized Yazidi areas in northern Iraq in 2014. Mr Abdulrahman, who is the leading human rights monitor in Syria with a network of informants throughout the country, says he is worried that international attention is entirely focused on the Syrian army assault on Eastern Ghouta and “nobody is talking about” the potential slaughter of the Kurds and other minorities in Afrin.

He says that the two situations are similar since “President Bashar al-Assad’s forces have taken 60 per cent of Ghouta and [President Recep Tayyip] Erdogan’s forces have taken 60 per cent of Afrin.” He says that as many as one million Kurds may be threatened and adds that it is becoming extremely difficult for them to escape from Afrin because Syrian government checkpoints on the only road leading south to Aleppo “are demanding bribes of up to $4,000 per family to let people through.”

Mr Abdulrahman points to growing evidence drawn from videos taken by themselves of militiamen claiming to be members of the Free Syrian Army (FSA) that the units advancing ahead of regular Turkish troops are extreme jihadis. This has previously been asserted by a former Isis member in an interview published by The Independent last month who said that many of his former comrades had been recruited and retrained by the Turkish military. He said that Isis recruits had been instructed by Turkish trainers not to use their traditional tactics, such as the of extensive use of car bombs, because this would identify them as terrorists. He suspected that Isis fighters would be used as cannon fodder in Turkey’s war against the Kurdish People’s Protection Units (YPG) and then discarded.

As the Turkish army closes in on Afrin and the Syrian army penetrates deeply into the opposition stronghold of Eastern Ghouta, people in both areas fear that they will be the victims of enforced demographic change. One Kurdish observer in Iraq said that he thought Mr Erdogan, who has claimed that the majority in Afrin is not Kurdish, will “bring in Turkmen and others to replace the Kurdish population."

Isis is particularly hostile to the US-backed YPG, as its most effective enemy which drove it out of a quarter of Syrian territory and captured the de facto Isis capital of Raqqa last October after a four-month siege.

As Mr Abdulrahman says, the sieges of Afrin and Eastern Ghouta have much in common, though the number of those trapped in Afrin may be larger. Motives for refusing to leave are also much the same. “I will never leave Ghouta,” said Haytham Bakkar, an anti-government journalist living there, speaking just as the present Syrian Army assault was getting underway. “We have lived here for hundreds and thousands of years. Here our grandparents lived. Here are our houses and tombs. We were born here and we will die here. Our souls and roots are here.”

Bakkar says that most people in Eastern Ghouta are convinced that their departure is part of a broader government plan to make drastic demographic changes whereby their property would be given to others. He says that even if people survived the dangerous journey out of the area, they did not want “to watch TV news and see strangers living in our homes.”

Kurds make a similar calculation, but it is also becoming extremely dangerous for them to try to flee. Precedents have already been set for ethnic and sectarian cleansing all over Syria since 2011 as those in control oust members of other communities.

Turkish attack on Afrin, northern Syria – in pictures Show all 9 1 /9 Turkish attack on Afrin, northern Syria – in pictures Turkish attack on Afrin, northern Syria – in pictures Smoke billows following a Turkish airstrike on a village in the Afrin district, on 28 January, 2018. Turkey launched operation "Olive Branch" on January 20 against the Kurdish People's Protection Units (YPG) militia in Afrin, supporting Syrian opposition fighters with ground troops and air strikes AFP Turkish attack on Afrin, northern Syria – in pictures Smoke billows from surrounding villages during the Turkish military operation against the Kurdish enclave on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures Twenty-year old Kifah al-Moussa, a Syrian Arab woman living among the Kurds of Afrin province, was working on a chicken farm in the village of Maryameen when a Turkish aircraft bombed the building at midday on 21 January, wounding her in the chest. When she recovered consciousness, she found eight people from one family lying dead around her Yara Ismail Turkish attack on Afrin, northern Syria – in pictures Mohamed Hussein, a 58-year-old Kurdish farmer, lies in the Afrin hospital, wounded in the head and eye after his home was bombed by Turkish aircraft on the second night of the attack Yara Ismail Turkish attack on Afrin, northern Syria – in pictures Syrian Kurds sit on benches overlooking a street in Afrin, on 28 January, 2018. Above is a memorial to ‘martyrs’ who died in the fight against Isis AFP/Getty Turkish attack on Afrin, northern Syria – in pictures Smoke is seen rising on the Syrian side of the border, at Hassa, near Hatay, southern Turkey as Turkish jet fighters hit People's Protection Unit (YPG) positions, on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures A Turkish made T-155 Firtina (Storm) howitzer is dispatched to the border at Hassa near Hatay, southern Turkey, on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures A Turkish soldier waves a flag on Mount Barsaya, northeast of Afrin, on 28 January, 2018 Reuters Turkish attack on Afrin, northern Syria – in pictures Turkey-backed Free Syrian Army fighters are seen in Barsaya mountain, northeast of Afrin, on 28 January, 2018 Reuters

The YPG is a formidable force and the YPG spokesman Nouri Mahmoud says that the group has 10,000 fighters in the enclave who would fight to the end. He says that Kurds are already being displaced and “in one village alone 600 people were told to go.” He said that the Kurds feared a genocide was in the making and complained that “the international media focus on Eastern Ghouta has given the Turks the opportunity to step up their attack on Afrin without the rest of the world paying much attention”. The Kurdish authorities are trying to publicise the sufferings of civilians in Afrin, but are so far not having much success.

In the long term – and possibly in the short term – Afrin may prove to be indefensible. It is surrounded by Turkish forces and their FSA allies who are vastly superior in numbers and heavy weapons and are able to use air power and artillery without opposition.

None of the foreign players in the Syrian crisis show any sign of intervening against Turkey. The Turks were able to invade Afrin on 20 January because Russia decided it would no longer defend its airspace as it had been doing previously. Kurdish leaders say they believe that Russia, Iran and Turkey have agreed that Turkey will get Afrin, possibly in exchange for the Turks agreeing to drop their support for the one big remaining anti-Assad enclave in Idlib.