Foreign fightersCerwyn Moore & Paul Tumelty (2008) Foreign Fighters and the Case of Chechnya: A Critical Assessment, Studies in Conflict & Terrorism, 31:5, 412-433. have fought on both sides of the Iraqi civil war and the broader Iraqi conflict.

Reasons

Jihadism Many of the foreign fighters in Syria and Iraq were drawn to the jihadist ideology, although experts note that religion is not the only motivation:

From ignorant novices who view the trips as a rite of passage, die-hard militants looking for combat and martyrdom, and individuals who go for humanitarian reasons but get drawn into conflict, individuals become foreign fighters for a range of reasons: boredom; intergenerational tensions; the search for greater meaning in life; perceived adventure; attempts to impress the local community or the opposite sex; a desire for increased credibility; to belong or gain peer acceptance; revenge; or misguided conflict experience expectations.

Mercenaries and private contractors In addition to volunteer foreign fighters, there are several private military companies operating in Iraq and Syria, such as the Wagner Group and the Slavonic Corps.

Islamic State foreign fighters According to figures collected by the Soufan Group in 2016, between 27,000 and 31,000 people including women and children who would not normally engage in conflict had traveled to Syria and Iraq to join the Islamic State and other extremist groups fighting in the region. One reason suggested for the influx of foreigners in the fight is that the Syrian government took no steps to curtail the inflow of foreigners moving into Iraq during the Iraqi insurgency. Their numbers continued to increase, however, and by 2013 may have numbered more than 11,000. The Turkish border was how most jihadis entered Syria.

An October 2016 World Bank study found that "ISIL's foreign fighters are surprisingly well-educated." Using the fighters' self-reported educational levels, the study concluded that "69% of recruits reported at least a secondary-level education" of which "a large fraction have gone on to study at university" and also that "only 15% of recruits left school before high school; less than 2% are illiterate." The study also found that foreign fighters are often more educated than their countrymen where those "from Europe and in Central Asia have similar levels of education to their countrymen" while those "from the Middle East, North Africa, and South and East Asia are significantly more educated than what is typical in their home nations." The report notes that its conclusions that terrorism is not driven by poverty and low levels of education does not conform with previous research. However, the report did find a strong correlation "between a country's male unemployment rate and the propensity of the country to supply foreign fighters" leading the report to recommend that governments pursue a policy of lowering the unemployment rate among the educated as a counter-terrorism strategy.

Origins of foreign fighters

Fighters include those from the Gulf Arab States, the Levant, the Maghreb, Turkey, Egypt, Sudan, the Muslim regions of Eastern Africa, the Muslim regions of the Balkans (especially Bosnia and Herzegovina, Kosovo and Albania), the Muslim regions of Russia (especially the North Caucasus), the Muslim regions of Southeast Asia, and many Western countries.Mark Youngman and Cerwyn Moore (2017) ‘Russian-Speaking’ Fighters in Syria, Iraq and at Home: Consequences and Context'

A 7 December 2015 report by the Soufan Group gave estimates for the number of foreign fighters in Syria and Iraq by their country and region of origin based on information dated between 2014 and 2015. The study, which only included foreign fighters with the Islamic State, the al-Nusra Front and other Sunni jihadist factions, listed the countries with the largest number of foreign fighters were Tunisia (6000), Saudi Arabia (2500), Russia (2400), Turkey (2100), Jordan (2000+) while the number of fighters by region was reported to be: the Middle East (8240), the Maghreb (8000), Western Europe (5000), former Soviet Republics (4700), Southeast Asia (900), the Balkans (875), and North America (289).

Of Western Europe's estimated 5000 total fighters, almost 4000 fighters were produced by just five Western European countries: France (1700), Germany (760), the United Kingdom (760), Belgium (470) and Sweden (300). Between 2014 and 2015, the report estimated a nearly 300% increase in the number of fighters originating from Russia and Central Asia whereas the total number of fighters traveling to Syria and Iraq had become "relatively flat." The report mentioned that the flow of foreign fighters "is neither uniform by region nor by country," with some countries having distinguishable "Hotbeds of recruitment" with some hotbeds, such as the Lisleby district of Norway's Fredrikstad which is populated by only 6000 people, being small and relatively new while other cities and regions, such as Tunisia's Bizerte and Ben Gardane, Libya's Derna, Georgia's Pankisi Gorge, and Brussel's Molenbeek, "are well-established incubators and radiators of extremist behavior."

The Soufan Group reported on 15 October 2016 that there has been "a significant increase in the number of foreign fighters travelling to Syria" since 2014. The U.S. State Department reported on 2 June 2016 that their "intelligence community" estimates that possibly "in excess of 40,000 total foreign fighters have gone to the conflict [in Syria] and from over 100 countries".

The phenomenon causes concerns in the home countries of the foreign fighters. The phenomenon is not new, but the size and variety of origins in this case were unusual.

Arab world In 2012, it was reported that most recruits to Syria are Arabs (Lebanese, Iraqis, Jordanians, Palestinians, Kuwaitis, Tunisians, Libyans, Algerians, Egyptians, Saudis, Sudanese and Yemenis). The largest contingents of about 500-900 fighters came from Syria's neighbors: Lebanese, Iraqis, Palestinians and Jordanians, many of whom fought U.S. forces in Iraq. The second-largest contingent was from Arab countries in North Africa: around 75-300 fighters from Libya, Tunisia, and Algeria. Al Qaeda leader Ayman al-Zawahiri called for a jihad in Syria with the main target of message said to be Lebanon, Jordan, Turkey and Iraq.

Gulf states Bahraini Shia youth traveled to receive Iranian training in camps and battlefronts in Iran, Lebanon, Iraq, and Syria.

Libya Towards the end of 2014, the city of Derna reportedly swore allegiance to the Islamic State, the first outside Syria or Iraq.

Iran In 2018, Tehran said that 2,100 Iranian soldiers have been killed in Syria and Iraq over the past seven years.

Georgia According to Georgia's State Security Service, around 50 Georgian citizens, principally from the Kist (Chechen)-populated Pankisi Gorge, had joined the Islamist groups in Syria and Iraq as of June 2016. By June 2017, at least 25 citizens of Georgia have died in these conflicts.

China Jihadist foreign fighters

Uyghurs appeared in an Islamic State film. Uyghur children appeared in an Islamic State video. The Islamic State Uyghur members attacked the "moderate Syrian rebel" members who were allied to the Turkistan Islamic Party. The Turkistan Islamic Party, linked to Al-Qaeda, was criticized by the Islamic State video. Children with weapons appeared in the video. Iraq was the location of the footage. The Islamic State's number of Uyghur fighters is much smaller than that of the Turkistan Islamic Party's.

Central Asia A few Kazakhs have joined the Islamic State in Syria and Iraq. the Islamic State released a video called "Race Toward Good" showing Kazakh children being trained as fighters. The families of Kazakh fighters have accompanied them to Syria including children and women. Many Kazakhs who lived under the Islamic State were women and children who were forcibly brought to Syria. The United Nations presented in 2019 Kazakhstan's repatriation initiative for other countries to model.

Uzbek Jihadist groups reportedly operated four training camps located Iraq and Syria in 2015.

The Uzbek group Katibat al Imam al Bukhari, also called Imam Bukhari Jamaat, has separate groups in Syria and Adghanistan. It pledged allegiance to the Taliban in 2015. Uzbek foreign fighters have flocked to Katibat Imam al-Bukhari. Salahuddin al-Uzbeki is the leader of Imam Bukhari Jamaat and his son Umar, a 16 year old teenager, died while fighting in Aleppo against the Syrian military. A member of Imam Bukhari Jamaat defended the utilization of child soldiers. On the VK social networking website, an illustration of a militant aiming an RPG at Santa Claus' flying sleigh was posted by Imam Bukhari Jamaat in 2015. Child soldiers were being drilled by Imam Bukhari Jamaat in 2016. They battled in Aleppo and Latakia's Jabal al Akrad region. The group participated in the Siege of al-Fu'ah and Kafriya.

The Islamic State has also recruited hundreds of Tajiks from Tajikistan to fight in Iraq as well. Once the Central Asians died in battle, their wives were given to other fighters.

Former Yugoslavia In September 2014, a total of 48 ethnic Albanians from several countries were killed fighting in Syria and Iraq. According to the Kosovar Centre for Security Studies, around 60 Kosovar fighters have been killed in combat as of March 2016. As of March 2016, the Albanian Government estimates that over 100 Albanian citizens have joined militant groups in Syria and Iraq, 18 of whom have been killed and 12 wounded.

In total, approximately 240 to 320 Bosnians and their family members traveled to Iraq and Syria between 2012 and 2016 to join extremist groups such as ISIS, and several figures like Husein ‘Bilal’ Bosnić and Bajro Ikanović were involved in recruiting or leading fighters.

Approximately 320 Bosnians, including adults and children, traveled to Iraq and Syria to join extremist groups; of these, around 88–130 Bosnians were killed, about 46–50 returned to Bosnia, and over 90 remained in the conflict zones or disappeared.

Russia Besides Jaish al-Muhajireen wal-Ansar, numerous other small factions and groups involving Russian-speaking foreign fighters, including some with links to the North Caucasus, are active in parts of Syria and Iraq.Cerwyn Moore (2015) Foreign Bodies: Transnational Activism, the Insurgency in the North Caucasus and "Beyond", Terrorism and Political Violence, vol.27, no.3, 395-415. As of September 2015, according to Russian Civic Chamber's commission on public diplomacy and compatriots abroad, approximately 2,500 Russian nationals and 7,000 citizens of other post-Soviet republics were fighting alongside the Islamic State."Security Service At Moscow Airport Detains Siberian Man Suspected To Join ISIS In Syria". IBTimes. 24 September 2015.

Southeast Asia Indonesia and Malaysia are the main source of foreign fighters from Southeast Asia with an estimated 500 Indonesians and 200 Malaysians have travelling to Syria to fight for the Islamic State. It is also suspected that more than 200 Filipinos, mostly the members of Abu Sayyaf (ASG) and Bangsamoro Islamic Freedom Fighters (BIFF) are training and fighting in Iraq and Syria under Islamic State.

In March 2019, the Malaysian Government has announced that it would allow Malaysian foreign fighters to return provided that they comply with checks and enforcement and complete a one-month government-run rehabilitation programme. This rehabilitation program involves returnees being examined by psychologists and clerics. Ayob Khan Mydin Pitchay, the counter-terrorism head of the Malaysian Special Branch, has confirmed that 11 Malaysians have returned including eight men, a woman, and two young children. The men were charged in court and convicted while the woman attended a rehabilitation programme.

Western countries Belgium