Roughly 30,000? Policy Brief
Phi Beta Iota: Missing from this excellent work is an examination of two major factors feeding the supply of foreign fighters. Factor One is the unemployment rate in Europe and the destabilization and displacement environment in Central Asia, the Middle East, and North Africa that the USA has itself created with its elective wars and gratuitous drone assassinations and other measures. Factor Two is the liberal funding from Saudi Arabia, Qatar, and the United Arab Emirates (UAE) that make possible the migration of unemployed destitute individuals from the frying pan into the fire.