As Jordan reels from the horrific killing of one of its fighter pilots by Islamic State militants, the death also highlights how inextricably involved the country has become in the conflict in Syria.
Jordan shares an extensive border with Syria, and the proximity has made it one of the main recipients of refugees from the country, as well as a host for covert U.S.-led training of Syrian rebels. While this flow of Syrians into Jordan has raised concerns over security and strain on resources, there's also worry over the significant number of Jordanians who have become foreign fighters in Syria.
Out of the countries adding to the militants in Syria and Iraq, few are in the same league as Jordan. According to the most recent figures by The International Centre for the Study of Radicalisation and Political Violence, Jordan has an estimated 1,500 citizens fighting in Syria and Iraq. Only Saudi Arabia and Tunisia are believed to have contributed higher numbers of militants, with high-end estimates of 2,500 and 3,000, respectively.
Both of these countries have millions more citizens to draw from as well, giving Saudi Arabia a fighters per capita ratio of 107 per million and Tunisia 280 per million, Radio Free Europe reports. Jordan's ratio is reported as 315 per million, putting them as the top contributor of foreign fighters to Iraq and Syria per capita.
One of the prominent cities from which Jordanians emerge as combatants is reportedly Zarqa, birthplace of Abu Musab al-Zarqawi -- who led the Islamic State's precursor, al Qaeda in Iraq. The New York Times reported this past April that one-third of the foreign fighters heading to Syria from Jordan were coming from Zarqa, abruptly leaving town "only to resurface across the border with the Nusra Front, Syria’s Qaeda affiliate, or the Islamic State."
It is hard to estimate the number of Jordanian fighters choosing to join Islamic State militants. A 2014 report by The Soufan Group points out there's also been no official estimate given by Jordan officials on the number of Jordanians fighting in Syria, let alone with the Islamic State group.
The ICSR report, which estimates there are 20,730 total foreign fighters in Syria and Iraq, does not distinguish which group the combatants join. ICSR director Peter Neumann said in an interview with The WorldPost that around 80 percent of Western foreign fighters join the Islamic State group, while those from Arab nations tend to go to a more diverse range of militant groups.
There's been much hand-wringing over the effect that the multitude of foreign fighters will have on their home countries, with some analysts claiming the threat is overblown while others insist on increased security. Jordan is opting for the latter, with a harsh anti-terror law in place that features lengthy prison term for alleged Islamic State supporters, including five to 15 years in jail for posting the group's videos.
As of October 2014, between 60 and 90 people have reportedly been arrested under the law for alleged connections to the Islamic State group, a number that is likely to rise. In the wake of the killing of Jordanian pilot Muath al-Kaseasbeh, Jordan's King Abdullah II vowed to continue the fight against the Islamic State on Wednesday, declaring, "We are waging this war to protect our faith, our values and human principles and our war for their sake will be relentless."