black math: getting more from the foreign fighter numbers

Yeah maybe I’ll learn to understand /Drawing a square with a pencil in hand yeah 

In the  the run-up to the UNSC resolution on foreign fighters, a number of estimates for Sunni foreign fighters in Syria and Iraq circulated. Estimates tend to come from the December 2013 ISCR study, the Soufan Group report or a combination of both. The Economist, the New York Times, the Associated Press and RFE/RL all carried graphs or visualizations of the numbers. The numbers in these publications all looked only at overall totals and in some cases did not reflect current government estimates or give numbers for dead and returned fighters.

In an effort to understand more about the numbers, the data below was compiled from press reporting (about 200 articles), government estimates, the ISCR reports, the Soufan group, and articles by Aaron Zelin in the CTC and blogs like jihadology. These numbers are an estimate and for a 65 country sample. This sample is missing at least 17 countries based on statements quoting CIA estimates of 15 000 foreign fighters from 80 countries and the fact that there are 17 000 fighters in the estimates suggests some over-estimations by some countries or sources.

The goal of the estimate below was to look at not just overall numbers but to disaggregate the data and examine the number of dead foreign fighters and returnees. It is probable that the numbers underestimate foreign fighter deaths and the returnee numbers are better for some regions than others. The overall figures should be subject to caution as the reporting from some regions is uneven. Estimates for Western Europe are possibly more reliable as they are derived for the most part from government estimates which contain relatively good levels of detail. Analysts that are specialists in a region will likely notice where the estimates are missing data or over-estimating numbers.

The 65 country survey of reporting on foreign fighters returned an estimate of 17 663 foreign fighters with 1623 deceased and 1986 returnees. Based on this sample, the Middle East (35%) and North Africa (32%) account for 67% of the foreign fighters. Western Europe accounts for 16% of foreign fighters and the Former-USSR a further 9%. The other regions account for the remaining 9% of fighters; Africa, Asia-Pacific, Western Balkans, and South Asia.

Foreign Fighters by Region

FF region

Region Foreign Fighters
Africa 170
Asia-Pacific 468
Former USSR 1585
Middle East 6141
North Africa 5660
North America 42
South Asia 385
Western Balkans 442
Western Europe 2770

The data are presented as raw estimates, and as population per million estimates. Jordan, Lebanon and Tunisia are the three countries of origin which figure in both measures of foreign fighter participation in Syria and Iraq. Population adjusted figures see the Middle East and North Africa occupy five places with Balkan states taking three places.

Top 10 Countries of Origin

FF raw

Foreign Fighters Per Million Inhabitants

ff pop

Foreign Fighters from Western Europe


French estimate excludes persons still in France wanting to travel and individuals in transit. 

Foreign Fighters from Western Europe – Casualties, Returnees etc

dead return

United Kingdom estimate does not take into account the 100 or so foreign fighters rumoured to be in Turkey and seeking to leave the region. 

Approximately 1 in 4 fighters has returned from Syria and Iraq to Western Europe and the Western Balkans. About 1 in 10 fighters from Western Europe have been killed and 1.5 from the Western Balkans. The European states have an average returnee rate of 27% and a casualty rate of 10%. There is variation between states with some having returnee rates as high as 50% (Sweden and the United Kingdom) and as low as 4% (Switzerland). The Balkans have a 23% returnee rate and a 15% casualty rate, again there is variation between states and an absence of data for some of them.

Foreign Fighters from the Western Balkans


Russia, Ukraine, Georgia, Azerbaijan and the ‘Stans


Plots, Attack, Plot Tempo

Based on the data collected by Andrew Zammit there has been one attack in the EU and 6 plots between October 2013 and October 2014 or the equivalent of an event every two months, and 1 in 7 of these events has been successful. Belgium (1 attack and 1 plot), France (1), United Kingdom (2), Netherlands (1), Norway (1). For an estimated 755 returnees to Western Europe this represents domestic attack activity for about 1 in 100 returnees.One scenario would suggest that based on current trends there are potentially another 20+ plots (for circa 3000 foreign fighters) which could take up to 4 years to materialise if the tempo of a 1 plot every 2 months is maintained. Based on the current plot to attack ratio at least 4 could be successful. This is a long way from the oft-cited 1 in 9 ratio. However, political violence is not necessarily a linear process and the frequency and tempo of plots at this time could either drop or increase depending on evolutions in Syria and Iraq as well as state responses in countries of origin. In reality, the numbers suggest a need for a focus on resilience and mitigation and less one which suggests that arresting foreign fighters and imprisoning them will stop attacks and limit a amorphous, ill-defined threat.

Obviously, the numbers only tell a part of the story and do not reflect the varying motivations of fighters, the different networks that operate or the clusters of fighters that have traveled. The data are not detailed enough at this level to indicate changes in the flows of fighters or when fighters began moving from Jabhat al-Nusra to ISIS or when more females and children started to travel. Nonetheless, the numbers do suggest that fighters are returning home, that most of them have done so without engaging in violence in their state of origin but they don’t tell us why fighters returned or without what purpose. The numbers tell only part of the story.

Comments or corrections for the dataset are welcome. The data is available for research purposes.