The long arm of the brutal Islamic State organization is reaching into the European continent and further afield, drawing growing numbers of young disaffected citizens to its more-radical-than-al-Qaida ranks. Many of these foreigners, say European researchers, are young converts to Islam who are likely to fall prey to particularly extremist interpretations of the religion.

At present, some European governments are tightening security measures to prevent possible terror attacks by the foreign-trained, French- and English-speaking jihadis, while local human rights groups warn against the possibly illegal arrest of minors.

The presence of Western-educated fighters in what was formerly called the Islamic State in Syria and Iraq, gained particular attention after release of a video showing the recent beheading of U.S. journalist James Foley by a masked executioner with a London accent. But European nations have been worrying for quite a while about their citizens joining the radical group which declared the birth of an Islamic State in June.

British Prime Minister David Cameron, for one, has recently authorized police and security forces to confiscate passports of suspected terrorists at the borders and to impose restrictions on where they live. French police have arrested a number of young men and women, some as young as 15, who were suspected of planning to join the Islamic State. Meanwhile, human rights groups in France have protested the arrests of minors, arguing that this violates the UN International Convention of the Rights of the Child.

“The presence of European fighters in Syria, and lately also in Iraq, has been unprecedented in both its scope and speed," Jeanine de Roy van Zuijdewijn, a researcher at the Hague's International Centre for Counter-Terrorism, tells Haaretz.

"While the phenomenon of Western Muslims joining a fight somewhere else is certainly not new – think of Afghanistan, Bosnia, Iraq, Chechnya, and Somalia – we have not seen it on this scale before. It has been estimated by the [London-based] International Centre for the Study of Radicalisation and Political Violence that around 2,000 Europeans have gone to Syria and the numbers of Americans and Australians are increasing as well,” she adds.

The actual strength of the Islamic State is highly disputed: The RAND Corporation, a nonprofit global policy think tank, estimates its ranks to number between 10,000 and 20,000 men. Since many of the organization's fighters, especially those born abroad and new to Islam, don’t speak Arabic, the Islamic State has broken its forces down into smaller units whose operations and training are conducted in foreign languages.

Meanings of 'convert'

The countries that apparently export the most Islamic State fighters are France (700 men, according to President Francois Hollande); the United Kingdom (at least 500, according to the Soufan Group, an international strategic consultancy firm); Germany (about 320, according to local news reports); and Belgium (approximately 350, according to The New York Times).

Analysts have also noted among the Islamic State' European-born forces a high proportion of converts without any family ties to Islam, despite the fact that converts represent only a small proportion of the continent's Muslim population.

Prof. Mathieu Guidère, a French scholar of cognitive sciences as they are applied to Islam, explains to Haaretz that converts represent around 60 percent of the French jihadis who are currently fighting with the Islamic State, or who are thinking of joining its ranks (He bases his estimate of the latter on research conducted in the social media and in other forms of correspondence.)

"The vast majority" of the converts, Guidère confirms, are people of Western descent who turn to Islam, although in jihadi circles the term “convert” may also apply to secular and moderate Muslims who embrace an extremist ideology.

“In countries such as Belgium and Germany they [converts] constitute 20 to 25 percent of the 'jihadi scene,'” says Lorenzo Vidino, a senior researcher at Zurich’s Center for Security Studies, in an interview. Vidino points out that one of the most famous radical Muslims in Germany is a convert: Gerhard Cuspert, a former rapper once known as “Deso Dog,” who is currently fighting in Syria with the Islamic State, according to the Al-Monitor media site .

Converts represent as much as 80 percent of the estimated 50 Italian citizens currently fighting with the Islamic State, Interior Minister Angelino Alfano said in a recent interview with the Corriere della Sera daily.

Asked why European converts are disproportionately represented among the radical Islamic State forces, analysts have different explanations. For her part, de Roy van Zuijdewijn speculates that “since they are new to the field of Islam, and their knowledge is often still limited, it is easier to target them with more extremist interpretations [of the religion].”

Others argue that there is a rising number of converts because jihadi groups are less attached to national identities and are instead focusing on pan-Islamic aims.

“Until, let’s say, 10 or 15 years ago ethnicity used to play a role in jihadism: [extremist Muslim] Pakistanis used to work mostly with other such Pakistanis, Moroccans with Moroccans, and so forth. Now, however, these barriers have fallen and consequently converts are more accepted,” says Vidino, the Zurich-based researcher.

Less nationalist approach

The more veteran extremist organizations such as the Talibans or Algeria’s Armed Islamic Group had stronger ethnic and national affiliations, but the Islamic State rejects the very idea of such identification, and has instead declared establishment of an Islamic caliphate.

Guidère, the French scholar, believes that European jihadis who lack a strong Islamic background are likely to be more drawn to groups such as the Islamic State because of their “revolutionary appeal” than by their religious ideology.

“There are people fighting with the Islamic State who don’t even know how to correctly recite the Shahada,” he says, referring to the Islamic declaration of faith. “They just want to fight the system, and to them jihadi groups have the same kind of appeal that radical left-wing terrorism used to have in the 1970s.”

Some people, however, believe that the emphasis on converts among the Islamic State ranks is misleading and potentially “dangerous.”

“This anti-convert attitudes are making things even more difficult for us,” says Layla Silvia Olivetti, an Italian writer who herself converted to Islam a decade ago and has authored a book about her experience. “We are already facing difficulties with our families of origin and within the mosques, which are often managed by Arab nationals ... And now we are being falsely depicted as potential terrorists.”

Indeed, Olivetti was recently labelled “a friend of the terrorists” by a conservative Italian newspaper, despite the fact that she has criticized both the Islamic State and other Muslims on her Facebook page. She also blames European authorities for failing to distinguish between locally born Muslims who went off to fight with the Islamic State, and those who joined more moderate, anti-Assad factions.

“They’re putting everybody in the same pot, as if there is no difference between freedom fighters and other thugs,” she says.