The Associated Press recently reported that as many as 20,000 foreign fighters have flocked to the "Islamic State" (IS) group from around the world, with 3,400 of those fighters suspected of having come from Western nations. By contrast, the Nigerian militant group Boko Haram - which predates IS by around a decade - has attracted few if any fighters from abroad in comparison to its Middle Eastern counterpart.

Social Media outreach

Many experts agree that a critical component in IS recruitment success has been its reliance on social media. The militant group has established a continual and pervasive presence across a number of platforms - including YouTube, Twitter and Vine - that has enabled it to reach countless potential recruits.

Boko Haram is another matter. The group's recent evolution of its propaganda prowess notwithstanding, it has largely shied away from online media platforms. Instead, it has trod the more traditional path of unremarkable propaganda videos distributed through media outlets - a drastic departure from IS' public relations juggernaut.

"We should expect [Islamic State] to have unprecedented social media because it's operating today, and social media has improved over time," says Max Abrahms, a Professor of Political Science at Northeastern University. "You'll notice that, when you compare the membership compositions of Boko Haram to Islamic State, you find that Boko Haram has worse social media and, not coincidentally, it also has a smaller percentage of fighters from abroad."

Mia Bloom, a Professor of Security Studies at University of Massachusetts-Lowell, agrees. "The fact remains that IS is built upon attracting foreign fighters and has created an entire social media machine to accomplish this. In essence, Boko Haram is very much a local movement with local concerns (closer in scope to groups like Al Shabaab)."

Geography

As Bloom touched upon, geography is also seen as instrumental in the disparity between the two groups' recruitment of foreign fighters. IS has exerted influence across an entire region, with an established presence in such countries as Syria, Iraq, Yemen, and Libya, among others. Control over such a wide swath of territory can be seen as appealing to impressionable potential jihadis, who are attracted to the influence of a group like IS that spans borders and continents.

"When easily excitable young Muslims consider where they should go they are likely to prefer Syria and Iraq where they can participate in building their dreamed caliphate," said Barak Menelsohn, Assistant Professor of Political Science at Haverford College, via email. "Boko Haram did not offer such an attraction."

Boko Haram's sphere of sphere of geographic and political influence is indeed much more limited. The group is largely confined to northeastern Nigeria, the area of its inception. Though the past several weeks has seen Boko Haram export its violence across the Nigerian border into neighboring countries, its focus remains principally on Nigeria. The localized nature of Nigeria's struggle with Boko Haram may thus serve to influence - i.e. deter - the numbers of foreign recruits that the group is able to attract.

Boko Haram's conflict is largely a localized one centered on the aim of establishing an Islamist state in northern Nigeria although the group has carried out operations in Niger, Chad, Cameroon, and Kenya," says Mary Beth Altier, a visiting clinical Assistant Professor at New York University's Center for Global Affairs, also via email. "IS, on the other hand, is reclaiming the lands of the historical Islamic caliphate so there is a historical aspect there, which can be used to legitimate the struggle and appeal to Muslims abroad."

"In addition, because the conflict is localized most members of Boko Haram speak the local language Hausa, a language not spoken by the majority of Muslims outside of the region. Members of IS, on the other hand, speak English and Arabic - languages understood by and that appeal to the majority of Muslims living in the West."

Overstated concern

The flood of foreign jihadis to such groups as IS remains a paramount concern for policymakers. In recent testimony before the House Homeland Security Committee, National Counterterrorism Center director Nicholas Rasmussen described the current numbers of foreign fighters as "unprecedented." Yet while the debate surrounding militant groups' recruitment of foreign fighters gives legitimate pause to officials, focus on the issue may be blown out of proportion.

"[A] relatively small number of foreigners have been attracted by the Islamic State's claims to be defending Islam against various forms of foreign interference," writes Stephen M. Walt, Professor of International Affairs at Harvard University and a renowned foreign affairs expert, in an email. "This narrative does not in any way justify the brutal acts that IS has undertaken, but it helps us understand why some people decide to join them. These sympathizers are in fact a very small percentage of the world's Muslim population, and there are signs that some recruits are becoming disillusioned once they realize what IS is really doing."