The Al-Qaeda, ISIS, T-SNA, and hundreds of other Islamist militias, both Syrian and international, have an aspect in common … they all recruit from the pool of the Sunni youth. These fighters are paid, and as incentives often allowed to loot, kidnap for ransom, etc. of the non Sunni minority populations. There is an open-door policy of shifting from one Sunni militia to another.
The current Syrian Undertaker government currently has many among its ranks that have been or still are fighters for these various jihadi militias. Quite likely the current ranking Understaker commanders, have been, or still are wanted criminals by many countries.