One would think that the main value of Western jihadists to terrorist organizations would be their passports and thus their ability to take the struggle directly to Western countries. Thomas Heghammer looks at the data in a new article in the American Political Science Review (open access, thanks Cambridge University Press). Most Western jihadists fight abroad and do not take the battle home but those who do return are more effective than jihadists that never went abroad. Here is the abstract:
This article studies variation in conflict theater choice by Western jihadists in an effort to understand their motivations. Some militants attack at home, whereas others join insurgencies abroad, but few scholars have asked why they make these different choices. Using open-source data, I estimate recruit supply for each theater, foreign fighter return rates, and returnee impact on domestic terrorist activity. The tentative data indicate that jihadists prefer foreign fighting, but a minority attacks at home after being radicalized, most often through foreign fighting or contact with a veteran. Most foreign fighters do not return for domestic operations, but those who do return are more effective operatives than nonveterans. The findings have implications for our understanding of the motivations of jihadists, for assessments of the terrorist threat posed by foreign fighters, and for counterterrorism policy.
This is all based on understandably limited data, which is available (in Excel format) from the author’s web-site. I do not know the ins and outs of this well enough to comment on how credible this is. Here is Heghammer’s earlier article on the rise of Muslim foreign fighters.