The name of the young ISIS fighter was not revealed in U.S. court proceedings, and the records are sealed. NPR has identified the fighter with the help of Iraqi officials and the teenager's family.

Sangar Khaleel, an Iraqi journalist who works for NPR, tells the story of three friends who served in an elite SWAT unit that helped drive ISIS from Mosul, and whose fight against ISIS isn't over.

Here is what it was like in the northern part of the country as the Syrian military started advancing to retake territory after the U.S. made way for Turkey's incursion against the Kurdish forces.