ISTANBUL, TURKEY — Judging by Yilmaz’s Tumblr account, the armed struggle against the Syrian regime is heartwarming and glamorous.

The Dutch national of Turkish descent, who has been fighting with extremists in Syria since last year, posted one photo of himself tenderly holding a pink-clad Syrian toddler. In another he poses solemnly in a black jacket and camouflage, one leg propped up, rifle by his side.

After the photo-sharing site Instagram closed his account, he moved to Tumblr, a blogging platform popular with fighters eager to show off their exploits on the battlefield. Today he uses the question-and-answer platform Ask.fm to field questions about his journey. Yilmaz quickly achieved fame among a niche audience of Syria watchers. The New York Times blogged about him. Other jihadis emulated him, posting photos of themselves on Facebook, Twitter, and other platforms looking happy and relaxed, pointing fingers in the air and casually slinging guns or other weapons.

In an interview with the Dutch TV show Nieuwsuur earlier this year, Yilmaz is depicted leading new recruits in target practice in a desolate Syrian field. “I think 90 percent of [the recruits] have never even fired a bullet in their lives, let alone [fought] on an actual battlefield,” he said. Only a decade ago, recruitment of jihadis happened via a fairly predictable, person-to-person pipeline. Young potential recruits were identified by radical operatives at their local mosques, then gradually indoctrinated in one-on-one conversations about the glorified efforts of their militant “brothers,” waging holy war in the name of Islam.

But these traditional recruitment tactics are increasingly giving way to sweeping efforts like Yilmaz’s. Twitter feeds, Facebook groups, and Instagram feeds are updated around the clock, reaching thousands of restless young Muslims in Europe and the US, luring them to the fight against the “infidel” regime of Syrian President Bashar al-Assad.

“Quite a few jihadi leaders now have their own Twitter accounts and use these to broadcast propaganda, but also interact with sympathizers and others,” says Aron Lund, an expert on the Syrian jihad. “That adds a new dimension, a fast-paced jihadi public debate that hadn’t really existed earlier.”

Jihad Online

The early days of Al Qaeda chat forums were far easier to monitor and control than today’s seemingly infinite number of sources, says Shiraz Maher, senior research fellow and head of outreach at the International Center for the Study of Radicalization (ICSR) at Kings College London.

“You could vet the members, where you knew who was there,” he says. Now, “It’s not just one person putting out a message and the message trickles down. You now have hundreds of fighters on the ground giving you a stream of information about what they’re doing.”

“Some forums still serve a role as guarantors of authenticity,” Mr. Lund notes, “but nowadays, whatever is posted by moderators pops up on YouTube, Twitter, Facebook, JustPaste and in other non-jihadist spaces within minutes. Some jihadist groups have even begun to release statements and upload links directly to Twitter and similar sites.”

Mr. Maher estimates that there are 2,000 European jihadis fighting in Syria, about 400 from France alone. US intelligence officials estimate there are about 100 Americans there. The uptick in Western recruits flocking to Syria has become a major security concern for their governments. Last week a Floridian named Moner Mohammad Abusalha became the first known American to carry out a suicide bomb attack in Syria. A photo of a happy, smiling Mr. Abusalha, holding a cat, quickly made the rounds on social media.

A Different Kind of Radicalization

Today, people are becoming radicalized largely on their own through Internet sites, forums, and videos, and their ranks have expanded beyond the shy, angry, marginalized young men once targeted by recruiters. “The entire radicalization and deployment process has become decentralized, individualized, and very rapid,” says a senior French counterterrorism official.

Dounia Bouzar, a Paris-based anthropologist who studies how young people in France are being targeted by radical Islamists, says that about 80 percent of foreign recruits to Syria’s war were radicalized before they reached the age of 21, nearly all of them through materials found online.

“Unlike earlier generations, these people aren’t being assigned or adopting an emir during the radicalization process, but only once they’ve become extremists on their own and arrive in the war zone,” Ms. Bouzar says.

From the outset of the Syrian conflict, the French official says he warned that graphic images of regime abuses would embolden would-be jihadis from Europe. Today, he looks back at that prediction with a sense of unhappy vindication.

“The longer the fighting [has] continued, the more terrible Assad’s violence has become. The worse that got, the more horrid the videos arising from it became. The more horrid the videos, the more impact they had on Islamists watching them online,” he says.

“That greater impact enhances the response of those who see them, which both speeds and strengthens the indoctrination and radicalization process. This eventually leads to more fighters flocking to jihadi militias, greater intensity in their battles with the regime, and worse footage of massacred combatants and civilians. It just keeps going on.”

“To most of us, such videos are repulsive, too horrible to watch,” Bouzar notes. “But when they’re seen by people watching them as virtual reality within the wider process of self-indoctrination, they become both intoxicating and motivating.”

‘Five-star Jihad’

With so much out there, there is a message to appeal to every kind of personality.

“We can identify different categories: the rewards for fighters and martyrs are bundled together as the virtues of jihad,” Maher says. “Then you can get another track talking about the obligations – don’t you know it’s a sin for you not to be in Syria? You have an obligation to defend your brothers and sisters.”

In March, a British fighter with the Islamic State of Iraq and the Levant (ISIS) donned a black North Face jacket and a face mask to film a recruitment video released on YouTube, extolling his “brothers and sisters” in Britain to join him on the battlefield. “By the grace of god, we have managed to bring in three or four beloved brothers of Islam,” he says. “You can see for yourself.”

There are other types of videos beyond the direct appeal. “Another category shows dead babies or homeless families [and is] designed to pull the heartstrings and draw you into Syria on those grounds,” says Mr. Maher. “The final category are the things that say, Look how cool this is! I’m on a tank, I have a gun, come out here and have the time of your life. It makes it look like jihadi summer camp. And they call it five-star jihad.”

This post originally appeared in Christian Science Monitor