BRUSSELS, BELGIUM—A man looks deep into the camera and pleads, in Arabic: “You, there in Europe, watching this video. I’m calling you.”

With urgency in his voice, he refers to children being murdered and women being raped at the hands of the enemy.

“We really need you here. This is your opportunity for paradise.”

“Paradise” via the distinct possibility of death on a Syrian battlefield, he means.

The man is calling for recruits to join the Al Nusra Front, an Al Qaeda affiliate that makes up part of Syria’s fragmented armed opposition fighting the government forces of Syria President Bashar Assad.

As unappealing as that “opportunity” may sound to the average European, the message has resonated with hundreds of youths here who have disappeared from their schools and homes and turned up in Syria.

Most are lifelong Muslims, while others are recent converts, a shocking number of them just teenagers, reportedly as young as 15.

Teenage Western recruits in Syria’s uprising throw yet another complex layer on the country’s two-year-old civil war, which has killed more than 70,000 and displaced millions more. As it is, Western powers are grappling with how best to aid rebel groups that are fighting alongside extremists to replace Assad’s regime.

London think-tank The International Center for the Study of Radicalization estimates as many as 600 Europeans have made this journey for jihad, with one of the largest contingents coming from Belgium. Belgian authorities estimate the number to be possibly as high as 80 individuals.

Among them is Jejoen Bontinck, an 18-year-old from Antwerp. His father, Dimitri Bontinck, is now in Aleppo in a desperate search for him, posting dramatic updates on Facebook. The father has said his son was “brainwashed” by members of the outlawed Islamist organization Sharia4Belgium who befriended him in a city park.

Brian de Mulder, a 19-year-old also from Antwerp, is known to be there too, also drawn in by the shadowy group.

When family learned he was in Syria earlier this year, they held a joint press conference with the openly anti-Muslim Belgian nationalist party, Vlaams Belang, calling on the government to do more against Sharia4Belgium and its ilk.

After Belgian authorities raided four dozen houses and arrested six on suspicion of supporting terrorism last month, de Mulder, now known as Abu Qasem Brazili, sent the family a message saying he never wanted to see them again.

They weren’t the only ones.

Two 16-year-olds from the Brussels suburb of Schaerbeek went missing for a few hours during their school’s Easter break. They then called their parents from Turkey to say they were headed into the Syrian war zone.

The mother of one of the teens flew to Turkey immediately, coming back to Belgium days later heartbroken, with no information about her son.

With little or no contact with their kids, families are left scouring Al Nusra public relations videos, looking for confirmation their children are still alive.

Such YouTube videos were one of the first signs of proof the Europeans were there fighting with the Islamists, says Hicham El-Mzairh, an Antwerp city councillor with Muslim roots who knows several of the young men who’ve gone.

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El-Mzairh points to a video, posted by a group he says is an offshoot of Al Nusra, of a firefight in which two of the young gunmen speak to each other in Dutch with what El-Mzairh describes as an unmistakable Antwerp accent.

Europol, the European police network, has just released its annual threat assessment, showing officials are taking stock of the problem.

The police force has noted “increasing numbers of radicalized (European Union) citizens travelling to regions of conflict to engage in terrorist activities,” Europol Director Rob Wainright wrote in the report.

“There is growing awareness of the threat posed by these people, should they return to the European Union intent on committing acts of terrorism,” he added.

Next door, The Netherlands has already ticked its national security level up a notch specifically because it learned so many Dutch residents had gone to the Syrian battlefields.

El-Mzairh, long active in Antwerp’s large Muslim community, said the alarm is justified. Long before the exodus to Syria raised new concerns, he’d been warning city leaders that Islamic radicals were making use of schools and parks to recruit young Belgians by exploiting a weak sense of community and inadequate guidance from old-fashioned imams in practising tolerant Islam integrated with European norms.

“If we don’t give them answers, they go to the internet,” he says, where they “become hypnotized” by the likes of Al Nusra. “The biggest recruiter is the Internet, it’s YouTube.”

And now, El-Mzairh said, the stringent Islam they’ve embraced to “fill the emptiness,” as he describes it, is “also asking them to kill people that try to stop them. So they’ve got a holy book in one hand and a weapon in the other.”

The Belgian government is at a loss over how they can be stopped. Border controls should be strengthened, most people agree. Another suggestion is to take away identity cards from those deemed vulnerable to extremist influences, so they can’t leave the country.

Schaerbeek Mayor Bernard Clerfayt scoffs at that idea, even after the two teenagers who were schoolmates of his own children ran away to Syria. His town is half Muslim, half Catholic or other religions, and he says there’s no way he’s going to punish the entire Muslim youth population for the acts of relatively few.

What Clerfayt has done, controversially, is to shut down some of the free food distribution services at the local train station. He says he learned there was radical Islamist propaganda being handed out with the meals and believes this connection may have been the link between the young teens and Syria.

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