© ReutersAn Isis fighter pictured in Raqqa, where Aristidou admitted to having been based.
Stefan Aristidou, from Enfield in north London, his British wife and Kary Paul Kleman, from Florida, last week surrendered to Turkish border police after more than two years in areas controlled by Isis, sources have confirmed to the Guardian.
Dozens more foreigners have fled in recent weeks, most caught as they tried to cross the frontier, as Isis's capacity to hold ground in Syria and Iraq collapses. Some - it is not known how many - are thought to have evaded capture and made it across the border into Turkey.
Aristidou, who is believed to be in his mid-20s, surrendered at the Kilis crossing in southern Turkey along with his wife - said to be a British woman of Bangladeshi heritage - and Kleman, 46. The American had arrived at the border with a Syrian wife and two Egyptian women, whose spouses had been killed inSyria or Iraq, Turkish officials said.
Aristidou said he had travelled to Syria to settle rather than fight. The officials said he had admitted to having been based in Raqqa and al-Bab, both of which had been Isis strongholds until al-Bab was recaptured by Turkish-backed Syrian opposition forces earlier this year. He went missing in April 2015 after flying to Larnaca in Cyprus. Neighbours told the Guardian that he had adopted Islamic dress shortly before he disappeared.
A spokeswoman for the UK Foreign and Commonwealth Office said: "We are in contact with the Turkish authorities following the detention of a British man on the Turkey/Syria border."
It is understood Turkish authorities released the British woman from custody, although she could still face charges. Prosecutors in the country are
© The Sun
The Briton could also face charges if he is extradited back to the UK. Any UK citizen arrested for fighting for Isis may face charges under the Terrorism Act, which carries a maximum penalty of life imprisonment. Those returning from Syria or Iraq will automatically have their cases reviewed by police to assess how much of a threat they may pose and what crimes they may have committed.
Kleman converted to Islam after his divorce from his first wife, according to his mother, and moved to Egypt in 2011 where he married an Egyptian woman. After that marriage collapsed he moved to Dubai and married his current wife, who is Syrian. They had three children and Kleman worked in IT for a school.
Kleman's family said on Wednesday that he travelled to Syria with his family in the summer of 2015 to help with humanitarian efforts. After arriving in Syria, however, Kleman said he realised that the information that had led him there "was all a scam," according to his mother, and his situation became confusing to his family. They said he had recently been in contact with US officials in Turkey, and had planned to reach the American embassy there and return to the US.
Relatives said they alerted the FBI that he may be in danger about 18 months ago. An agent told them the bureau needed to check that Kleman had not become involved with wrongdoing, according to Kleman's sister, Brenda Cummings, who said she "completely agreed" with their caution.
Sources within Isis have confirmed that the group's ranks in its last redoubt in Syria have rapidly shrunk as a ground offensive has edged towards Raqqa and Tabqa in the country's north-east, where foreign fighters had been extensively deployed over the past four years.
Officials in Turkey and Europe say an increasing number of Isis operatives who have joined the group since 2013 have contacted their embassies looking to return. Other, more ideologically committed members are thought to be intent on using the exodus to infiltrate Turkey and then travel onwards to Europe to seek vengeance for the crumbling caliphate, raising renewed fears of strikes on the continent.
Among them, western intelligence agencies believe, are prominent members of the group's external operations arm, who joined Isis from numerous European countries including Britain, France and Belgium, as well as Australia. At least 250 ideologically driven foreigners are thought to have been smuggled to Europe from late 2014 until mid-2016, with nearly all travelling through Turkey after crossing a now rigidly enforced border.
Turkish police claim to have made a series of arrests earlier this year that they say disrupted well-established smuggling routes, some through Greece and others through Bulgaria. However, intelligence officials in the region believe that some of those routes remain viable despite efforts to shut them down.
"Europe has to keep its guard up," said Shiraz Maher, deputy director of the International Centre for the Study of Radicalisation at King's College. "The threat will likely become more acute in the coming months and years as the pressures on Islamic State intensify."
Masrour Barzani, chancellor of security for the Kurdistan Regional Government in northern Iraq, said: "The nature of the fight against Isis will
© Huseyin Aldemir / AFPTurkish police
"However, the threat foreign fighters can still pose upon returning to their countries should not be underestimated."
Late last year an Australian senior Isis member, Neil Prakash, was arrested just inside the Turkish border after using a smuggler to cross from Syria. In a prosecution statement obtained by the Guardian, Prakash admitted to having joined Isis and fought with the group in a Syrian Kurdish town, Kobani, where he said he was wounded. He denied playing a broader role within the group and claimed he had been given permission by Isis leaders in Raqqa to leave the organisation for Idlib province.
The Australian government believes Prakash to be one of the country's most significant Isis members and that he may have been linked to its drone programme and have travelled to Turkey intending to make his way to Europe.
As attacks against Isis have intensified around its two main urban strongholds, Raqqa in Syria and Mosul in Iraq, the group has increasingly used drones as surveillance tools and to drop airborne bombs on advancing troops. Armed drones have been a regular feature of the Isis defence of Tabqa, to the west of Raqqa, a battle it appears to be close to losing to US-backed Kurdish troops.
In Mosul, meanwhile, the Iraqi-led fight for the west of the city has stalled, with Isis recapturing some districts it had lost in recent weeks. It remains entrenched in the north-west of the city and in lands between Mosul and Raqqa, from where the Isis leadership is believed to have largely withdrawn for the nearby city of Deir Azzour and the town of Mayadeen.
Up to 30,000 foreign fighters are thought to have crossed into Syria to fight with Isis. The US government estimates that as many as 25,000 of them have since been killed. Around 850 British fighters have joined Isis or other jihadi groups such al-Nusra Front and in some cases the war against the regime of the Syrian leader, Bashar al-Assad. It is believed around half of these fighters have returned to the UK and around 200 have died.
Maher said a military defeat of Isis would cripple the group's recruitment ability. "Islamic State has projected a narrative of momentum and success," he said. "Their slogan has been 'remaining and expanding', and a lot of young people bought into that. As the caliphate begins to crumble, that same appeal simply isn't there any more. It's potency and relevance has been diminished."
"What you will now see is the most hardened and committed members of the group retreat to the desert as Islamic State prepares for its next phase, as an aggressive insurgency in Syria and Iraq. However, a significant proportion of its recruits from Europe and the west will lose confidence in the group and defect or surrender."
Comment: Further reading: The Origins and Ultimate Purpose of ISIS: A Brief History of the US-Middle East Proxy War