In the aftermath of the sadistic murder of American journalist James Foley by a suspected London-born ISIS recruit, increasing attention is being paid to the radicalization of Muslims from the West who are joining the conflict in Iraq and Syria.

U.S. and European security services estimate that more than 1,000 of jihadist militants fighting in Iraq and Syria were drawn to the conflict from Western nations with some estimates putting the number as high as 3,000.

Business Insider compiled the graph below, which illustrates best estimates of where just some of those Western fighters originate.

Compiled by Business Insider, this chart shows best estimates of foreign fighters joining the conflict in Iraq and Syria. Up to 80% of fighters end up joining ISIS or related groups. Business Insider

Business Insider sought to use only official statements and credible reports in compiling the estimates.

The chart shows 700 recruits from France, 400 from the U.K., 320 from Germany, 250 from Belgium, 200 from Australia, 130 from the Netherlands, 100 from Canada, 100 from the U.S., and 51 from Spain.

The figures demonstrate alarming numbers from the U.K. and France in particular. In both countries, the integration of immigrant communities — and Islamic communities in particular— remains a hot-button political issue.

Per capita, Belgium is the biggest source of western ISIS recruits.

Joining ISIS

Given the chaotic nature of the fighting, people who have left their home countries to join the conflict are hard to track. Further, there are multiple militant groups on the ground in Iraq and Syria that could attract Western fighters.

But from the studies Business Insider analyzed, it appears the majority of those who join the conflict end up fighting for ISIS. Some experts, such as professor Peter Neumann of King's College London, estimate the number could be as high as 80%.

ISIS has been targeting Western recruits with social-media campaigns, slickly produced videos, and English-language publications.

The phenomena poses a special challenge to security services because the Western passports used by the fighters are not subject to the restrictions and visa requirements placed on many non-Western citizens.



"That's my boy." The message tweeted along with this image [censored] by Khaled Sharrouf, and Australian foreign fighter who joined ISIS. The image depicts Mr. Sharrouf's son, thought to be seven years old, holding a severed head. Twitter Western Response

Countries such as the U.K. and Australia are dealing with the growing threat posed by their citizens leaving to join ISIS by seeking to integrate divided communities and empower mainstream Muslims. They're also beefing up surveillance and canceling passports of suspected militants.

The Westerners joining the conflict are predominantly young men, though there are increasing reports of women and even children traveling to the region.

Innes Bowen, author of "Inside British Islam," told Business Insider there was no single type of person who becomes a radical in the U.K., and no single pathway to their ideology.

"There must be a range of motivations — a sense of adventure, a misplaced sense of duty or idealism — some of those recruited are well versed in ideology and the politics of their radical cause others are surprisingly ignorant," Bowen said.

The New Republic reports that two young men who joined the conflict from the U.K. this May purchased "Islam for Dummies" and "The Koran for Dummies" before leaving.