A French Islamist who fought as part of a jihadi rebel faction in Syria has said that foreign fighters with a "9/11 ideology" could return to the West, where they would pose a definitive security threat.
In an interview with the BBC the anonymous former rebel fighter told of how he had fought for an unnamed Islamist brigade, before leaving after it pledged its allegiance to Al Qaeda's Islamic State of Iraq and al-Shams (ISIS), saying that he opposed the brutal methods of the group - but not necessarily its vision for Syria.
The interview offers an intriguing insight into the mindset, ideology and motivations of the increasingly dominant Islamist rebel movement in Syria, which has eclipsed the more secular Free Syrian Army. It also once again highlights the growing security concerns shared by most Western countries over the increasingly large number of Western-born Islamists fighting in Syria - and the prospect of there return to their countries of birth at some point in the future.
Western states have recently opened diplomatic channels with the largest such faction - the Syrian Islamic Front (SIF) - in a bid to gain their support for upcoming peace talks in Geneva. The move has also been seen as an attempt to drive a wedge between the non-Al Qaeda-aligned factions fighting under the banner of SIF, and Al Qaeda franchises such as Al Nusra Front and ISIS, with whom they sometimes coordinate operations, particularly in the north of the country.
But such efforts are fraught with risks.
As the unnamed fighter, who chose to hide his identity, presumably out of concerns for his safety after publicly declaring his desertion, explained to his interviewer, whilst he and other Islamists in Syria did not support the killing of "blasphemers" or even the September 11 attacks on the World Trade Center, "the final goal is an Islamic state".
"We are all Al Qaeda in the sense of ideology and mindset," he declared.
Illustrating his point, he explained how his unit did not view members of the Shia Islamic sect as Muslims, and viewed the conflict through the prism of a religious sectarian war.
Echoing sentiments made by Al Qaeda leaders, he said that the Syrian civil war is "Definitely a fight against the Shia. Shia is not a sect of Islam. The difference between Sunni and Shia are so huge that they are not related to our religion in any way."
Syrian dictator Bashar al-Assad is a member of the Alawite sect - an offshoot of Shia Islam whose adherents make up around 10% of the Syrian population. His forces are backed by pro-government Shia and Alawite militias raised from within Syria itself, as well as foreign Shia jihadis from Iraq and Lebanon - most notably Hezbollah.
Shia Iran has provided crucial support to the Assad regime, including sending members of its own armed forces to train and fight alongside regime troops.
Relating how his brigade would treat members of Syria's tiny Shia minority in the areas they controlled, the former rebel said they found it so "irritating" to hear Shia referring to themselves as "Muslims", that "in areas we controlled we would force them to stop calling themselves Muslims."
Neither the interviewer nor the former jihadi revealed which precise brigade he had been fighting with, but given his description and the fact that it is said to have "pledged allegiance" to ISIS it was likely to have been the Nusra Front, which did precisely that back in August of this year. Many within the Nusra Front were unhappy about the decision to effectively merge the two groups at the time, and resisted it - causing some tension between different factions within the group ever since.
He also revealed how many Islamists are motivated to join the conflict and were encouraged on the battlefield itself by a saying - or "Hadith" - attributed to Mohammed, the founder of Islam, in which he declared that "if Islam in the Greater Syria region is corrupted, there will not be any correct Islam anywhere in the world."
The fact that such fundamentalist religious sentiments are shared by Al Qaeda-linked and independent Islamist rebel groups alike illustrates just how easy the ideological journey into the fold of Al Qaeda would be for many foreign fighters - a trend he claimed is on the increase.
And crucially - despite saying that he himself did not share such beliefs - he warned that "the same people with the same 9/11 ideology" existed among the large contingent of European Muslim extremists currently fighting in Syria. Alarmingly, he claimed that "Europeans" were the third-largest group of foreign jihadis in Syria, after "the Saudis and Chechens".
"Yes, I think they would be a danger to the West," he said, "I wouldn't want them to go back."