The Jihad in Jordan: Drivers of Radicalization into Violent Extremism in Jordan
"It is estimated that since the start of the Syrian conflict in 2011, over 30,000 foreign fighters have joined Sunni militant groups, such as ISIS and al-Qaeda, in Iraq and Syria. The Middle East, with approximately 11,000 foreign fighters, remains the primary source of foreign fighters in the Syrian and the Iraq conflict."
Anne Speckhard for the International Center for the Study of Violent Extremism (3/25/17)