A growing fear is that many of these recruits eventually return home to plan terrorist attacks on European soil. Although citizens of many countries across Europe have left home to wage jihad, a recent report by Brookings indicates that France, the United Kingdom, Germany, Belgium, and the Netherlands account for the largest percentage of European nationals who have fled to Syria.
Some estimates place the total from Western European countries to be close to 2,000 individuals, perhaps more. France, for example, is estimated to have had roughly 900 of its citizens enter Syria to join ISIS, and the corresponding figure for the United Kingdom has been placed at roughly 500 nationals.
Read the complete report here.