Number of foreign fighters worldwide soared by 71 % from 1990 to now . Syria and Iraq were most popular regions - mainly for IS and fighters - were targeted . United Nations report said fighters came from over half people 's countries . It estimated if IS was defeated foreign fighters could scatter across the globe .
Number of foreign fighters worldwide soared by 71 % from mid-2014 to now . Syria and Iraq were most popular regions - mainly for IS and Al-Nusra Front . United Nations report said fighters came from over half world 's countries . It warned if IS was defeated foreign fighters could scatter across the globe .