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Should I Stay or Should I Go? Explaining Variation in Western Jihadists' Choice between Domestic and Foreign Fighting


Authors: Hegghammer, Thomas 

Date of Publication: February 2013

Publication: American Political Science Review, p.1-15 doi:10.1017/S0003055412000615


Purpose of the study

Key questions were addressed

To understand different motivations of those militants who choose to conduct attacks ‘at home’ compared to those joining insurgencies abroad - why they make these different choices.

This article addresses both a social science puzzle and a policy problem. The puzzle is the unexplained variation in choice of attack location. If jihadists have similar aims, why the different travel patterns? The policy problem is that of assessing the domestic terrorist threat posed by those who leave. 


Design of the study


Empirical, based on a range of open source materials.

A new dataset was built, comprising Islamist attack plots and plotters in the West between 1990 and 2010 (the “Jihadi Plots in the West (JPW) Dataset). To construct the JPW Dataset, the author collated incident data from existing overviews by other scholars..

Number of participants



Empirically, the inquiry focuses on jihadists in North America, Western Europe, and Australia between 1990 and 2010.

Type of ‘participant’ 

Jihadists who have chosen to commit home-grown attacks or travelled abroad (mobilised to violence).

A “domestic fighter” is a person who perpetrates or tries to perpetrate violence in the West, whereas a “foreign fighter” is someone who leaves or tries to leave the West to fight somewhere else. “Domestic” here means “anywhere in the West,” so a French jihadist attacking in Germany counts as a domestic fighter. “Foreign fighting” includes any military activity (training or fighting), using any tactic (terrorist or guerrilla tactics), against any enemy (Western or non-Western)—so long as it occurs outside the West. Co-ethnic war volunteers (e.g., American-Iraqis going to Iraq) are counted as foreign fighters.

‘Plotters’ included only people who were directly involved in operational matters.


  • The author examined data to generate tentative estimates of the number of domestic and foreign fighters, the proportion of foreign fighters who return, and their impact on attack effectiveness. I also offer an explanation for the overall relative distribution.
  • Biographical information and evidence on declared intentions was sought, i.e. for the declared purpose of the initial trip abroad, coding three types of motivations: to fight abroad, to train abroad for a domestic attack, or unknown. Second, for other domestic fighters, the author looked for evidence indicating whether they had expressed a desire to travel abroad as foreign fighters before engaging in the domestic attack.

The article’s main contribution is to offer baseline estimates of Western jihadists’ theater choices and some evidence on the motivations underlying them. The findings contribute to a growing body of scholarship on Western jihadism, specifically to a line of research that disaggregates the behaviors and motivations of militant Islamists. The article also adds to the literature on foreign fighters by empirically exploring the conceptual distinction between foreign fighting and terrorism.

Key Findings 

Tentative data indicates that militants usually do not leave intending to return for a domestic attack, but a small minority acquire that motivation along the way and become more effective operatives on their return. This has implications for counterterrorism, especially for the handling of foreign fighters. 

Considered are three explanations for why foreign fighting has proved the more frequent choice of Western jihadists: (1) because it is easier, 2) because they need training, and (3) because they prefer it.

Opportunity, training and norms are discussed to explain differences.

Western jihadists may not all be equally motivated to attack in the West. In fact, the tentative data presented here indicate that most prefer to fight outside the West and that most foreign fighters do not “come home to roost.” However, the data also point to a veteran effect that makes returnees significantly more effective operatives.

Key recommendations 

The author does not suggest that Western jihadists are divided into two distinct camps, that no foreign fighters leave for training, or that foreign fighters are harmless. Motivations can be fickle at the individual level, some militants do go abroad intending to return, and those who do are dangerous indeed. In addition, norms are malleable, so supply rates and ratios may change in the future. 

Because findings pertain to past choices of jihadists as a group, they may be used to calibrate broad policy strategies, not to predict individual behaviour.

Findings are only valid for jihadists in the West. There is some evidence of a preference for foreign fighting among Islamists in Muslim countries, but more research is needed to confirm this.

Several policy implications are identified: 

First, to accurately measure domestic terrorist activity, analysts should distinguish more systematically between violence at home and abroad and consider abandoning the fuzzy term “homegrown terrorism.” 

Second, policy makers should distinguish between outgoing and returning foreign fighters and treat the latter as more of a threat. Prosecuting all aspiring foreign fighters as prospective domestic terrorists has limited preventive benefits, because so few of them, statistically speaking, will go on to attack the homeland. By the same logic, the use of agents provocateurs to draw aspiring foreign fighters into fake domestic plots may have limited preventive value. By contrast, returning foreign fighters and their contacts should be monitored very carefully.

Third, governments should adapt their communication strategies to the reality that most Islamists consider confined insurgency more legitimate than international terrorism.

Talk of insurgents and foreign fighters as “terrorists” will likely fall on deaf ears and may irritate rather than dissuade the fence-sitters. It is probably

Better to acknowledge the difference between domestic and foreign fighting and to discourage each activity with different sets of arguments.

Reveiwer Notes

The article covers:

The analysis focuses strictly on variation in theatre choice by radicalized Islamists. Excluded is the question of pre-choice radicalization (why they radicalized) or post-choice tactics (how they fight). 

More important, it does not attempt to explain individual differential choice because there is a lack biographical data on the foreign fighters. As such it examines the overall relative distribution, a task similar to that of the analyst who tries to understand an election outcome without having demographic data on all the voters. 

However, at the end the author tentatively probes the question of who stays and who goes.

Includes brief literature review on the topic.

Justification for dataset was noted as: “I started in 1990 because jihadi attacks in the West were rare before that time. I could not use established terrorism datasets (ITERATE, RAND/MIPT, and GTD) to estimate recruit supply, because they exclude foiled attacks and lack information on plot participants. More detailed incident overviews exist, but none covers the entire West for both the 1990s and 2000s."

Note that the landscape may have changed since this period so it is worth considering how findings may or may not be applicable to the problem of terrorism today. Might findings be different if a sample post-2010 was analysed? (The author recognises this in their conclusions.)

Findings may differ for other countries/ cultures/ areas of the world.

The author notes the complexity of estimating the supply of foreign fighters and proposes a way to generate rough estimates for comparative purposes.

Potential gaps in knowledge:

The article identified several questions for further research. Why do some militants proceed straight to domestic fighting without the “treatment” of foreign travel or veteran contact? Why do supply rates and ratios vary between countries and over time? Why do some destinations turn more foreign fighters into domestic fighters than others? Why do only some foreign fighters move on to domestic fighting? Do different types of foreign fighters (e.g., co-ethnic vs. non-co-ethnic ones) display different propensities to become domestic fighters?


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