While the Middle East remains the most dominant source of ISIS fighters, about a fifth of all foreign fighters in Iraq and Syria now come from Western Europe, according to the International Centre for the Study of Radicalisation and Political Violence (ICSR). Of those, Europe's largest countries have technically produced the most fighters. The ICSR estimates that France, for example, has sent 1,200 people to Sunni militant organizations in Iraq and Syria; and that both the United Kingdom and Germany have each contributed somewhere between 500 and 600 people. Larger populations, larger numbers of fighters ... that stands to reason. The countries that produce the most ISIS fighters per capita, however, are a bit more surprising.
Belgium, for example, now has more citizens fighting in Iraq and Syria per capita than any other European country (40 for every million people). In fact, the total number of fighters the ICSR estimates Belgium has sent overseas (440) is not far behind the numbers of much larger countries like the U.K. and Germany. The next two European countries with the most foreign fighters are equally surprising: Denmark (with 27 fighters for every million people) and Sweden (with 19). Are these figures indicative of larger problems? Are they clues to thwarting the next horrific attack? The ICSR's full list, as of January 2015, is below.