The Generational Waves of Jihadist Foreign Fighters

The number of transnational insurgents fighting in wars has increased dramatically recently. How are those fighting in Syria different from the foreign fighters who fought in previous jihadist wars?  

The international anti-fascist struggle of the International Brigade in the Spanish Civil War (1936-1939), famously depicted by a disillusioned George Orwell, still remains in the collective memory of successive generations in the West. Yet, the emergence of foreign fighters, defined as “non-citizens of conflict states who join insurgencies during civil conflicts,” as a significant threat to international security occurred primarily after the Soviet invasion of Afghanistan. The large numbers of individuals who flocked to Afghanistan to defend Muslim lands from an “infidel invasion,” colloquially known as “Afghan Arabs,” became the genesis of violent movements including al-Qaeda. Most notably, the jihadist foreign fighters (JFFs) fought against Serbian forces in Bosnia, Russian army in Chechnya, the US army and local government forces in Afghanistan and Iraq in the last several decades.

More recently, the rise of the self-styled Islamic State (IS) has resulted in an unprecedented spike in the number of foreign fighters. According to an estimate, some 40,000 individuals from many different parts of the world, from Trinidad and Tobago to China, joined the ranks of the IS and other jihadist organizations following the outbreak of war in Syria in 2011. This current wave of JFFs represents not just a quantitative increase but also an important qualitative change in the characteristics of individuals who travel abroad to fight for an Islamist cause. JFFs that were mobilized with the Syrian war represent a more diverse demographic group than the previous generations. We argue that this evolution of JFFs:

(1) makes it futile to search for distinctive traits that set them apart from the rest of the population;
(2) highlights the crucial role played by ideological framing in motivating jihadist mobilization;
(3) makes it important to prioritise policies that make it less feasible for individuals to join jihadist groups over policies based on profiling.

The Genesis and Ideology of the JFF Mobilization  

Mujahideen crossing in from Pakistan border to fight in Afghanistan in 1985. Image credit: Erwin Franzen/Wikimedia Commons.

The term jihad has a long and convoluted history with multiple connotations in Islamic thought and practice. But the Salafi-jihadist ideology, which espouses violence to restore a puritanical understanding of Islam, is a modern phenomenon that emerged during the Soviet occupation of Afghanistan.  Thousands of fighters from many different Muslim countries joined the Afghan resistance during this period. Salafi-jihadism gained a new focal point with the US invasion of Iraq in 2003 and had received new life with the deterioration of popular Arab uprisings into vicious civil wars or authoritarian backlashes by 2013.

The Salafi-jihadist ideology rests on two pillars. First, it offers a comprehensive identity for Sunni Muslims, transcending national, ethnic, and racial borders. This identity is perceived to face an existential threat by neo-imperialist powers and their local collaborators in Muslim lands.

Secondly, it urges the faithful to defend their fellow Muslims suffering under oppressive regimes and invading forces. From this perspective, crossing borders to fight on behalf of these Muslims has two distinctive characteristics. It is a defensive act as well as a religious obligation. In this sense, the notion of altruistic punishment, acting to harm members of an out-group at a personal cost, is central to the motivational frame of Salafi-jihadism. Muslims are expected to eschew their personal well-being for the collective goal of defending the members of their global community (umma) against aggressive forces. This motivational frame is also consistent with prospect theory’s basic cognitive insight that individuals are more likely to take risky actions when they perceive themselves as operating in the domain of losses (known as loss aversion). The images of Muslim suffering are disseminated widely in jihadist propaganda that aims to portray the status quo as unbearable for members of the community.

The Changing Nature of Jihadist Mobilization

The outbreak of the Syrian war and the rise of the IS have significantly expanded the appeal of Salaji-jihadist ideology for several reasons. First, the Syrian conflict, characterized by high levels of civilian suffering and deaths, has appeared to vindicate the Salafi-jihadist diagnosis of the Muslim world being under siege. The images of atrocities, devastated urban landscapes, decimated bodies, and desperate refugees are widely circulated via mass and social media outlets in Muslim countries.

Secondly, travelling to battlefields in Syria remained feasible and fairly easy for several years. Tens of thousands of individuals crossed the Turkish-Syrian border to join jihadist groups without much difficulty.

Finally, the IS differed from previous Salafi-jihadist groups through its ability to establish a state-like governing body in a vast territory. Consequently, its recruitment appeals went beyond a “brothers-in-arms” type of struggle and involved participation in a brand new Muslim society. It aimed to mobilize not only fighting-age males but also men and women with a variety of skills, and even children.

Case Study: Turkey’s Foreign Fighters

In our own work on JFFs from Turkey, we explore how the latest wave of jihadist mobilization has changed as a result of these developments. Using a sample of 477 JFFs from Turkey spanning three decades, we address two interrelated questions.  First, we look at how Turkish JFFs operating in Syria differ from their compatriots who operated in previous Islamist conflicts.  Using a machine learning approach, we find that JFFs who fought in Syria are more likely to be single, have no history of Islamist political activism, and no previous battlefield experience than previous generations of JFFs.  Secondly, we study how JFFs who joined the IS as opposed to other Islamist groups that have been in Syria since the outbreak of the Syrian war (e.g., al-Nusra Front). Individuals with no previous Islamist experience and no battlefield experience are more likely to be classified as being a member of the IS. Younger and middle-aged individuals are more likely to be classified as belonging to the IS as well.

The main takeaway is that the modern JFF battlefield, as manifest in Syria, seems to have brought significant changes in the demographics of fighters. JFFs traveling to Syria had less theological/ideological and political engagement than their counterparts who fought in previous jihadist conflicts. This divide is even more pronounced when comparing JFFs joining the IS with those joining other groups in Syria. The IS espouses the most uncompromising and reductionist version of Salafi-jihadism and declares fellow Muslims who do not subscribe to its ideology as infidels (takfir), a practice that receives condemnation even from other jihadist organizations. At the same time, its ideology appeals to a large number of individuals who are not well versed in Islam and lack a history of Islamist activism. The IS did not just want JFFs who were warriors; it has aimed to build a society of soldiers, scientists, clerics, doctors, and homemakers.


The post-Syria JFFs have diverse characteristics defying facile categorizations and making it futile to look for unique jihadist traits. They are not necessarily pious or political activists. The IS’s ability to attract followers with different skills and life experiences could be explained by its ideological claims of Muslim restoration. It promoted a nation-building project, restoring the unity of ummah under the Caliphate, with notable success in recruitment.  The IS can no longer capitalize on its project after a series of defeats and territorial loses it suffered in Iraq and Syria since 2015. However, if moral outrage caused by Muslim suffering persists, effectively countering the appeal of its violent ideology will remain a difficult, long-term challenge. It could be also very difficult to dismantle dense networks among battle-hardened surviving IS fighters that could facilitate their regrouping under more auspicious circumstances. Policies targeting such networks would be more effective than policies of profiling casting a wide net over and potentially criminalizing large demographic groups.

Güneş Murat Tezcür (Ph.D., University of Michigan) is the Jalal Talabani Chair of Kurdish Political Studies at the University of Central Florida. His work has appeared in many journals such as American Political Science ReviewComparative PoliticsJournal of Peace ResearchLaw and Society Review and Political Research Quarterly. He is also the author of Muslim Reformers in Iran and Turkey.

Clayton Besaw is a political psychologist and computational social scientist who is a PhD candidate at the University of Central Florida. He currently serves as a political events forecaster within One Earth Foundation Research’s forecasting track. His work has been published in Journal of Conflict Resolution and Conflict Management and Peace Science.