"IS had maintained training camps in the Syrian desert for many years, according to Gregory Waters, a research analyst at the Counter Extremism Project who closely follows IS activities in central Syria.

"These are the places where it trains the next generation of fighters — often children it recruits from northeast Syria — and where adult fighters can return to in between their operations," Waters told VOA. "While the central Syrian desert is under Russian and Syrian regime control, ISIS does not abide by these arbitrary lines.""