For years, extremists in and out of Xinjiang have turned to the internet to spread their separatist ideologies. Recruitment and propaganda videos, including some that taught how to make weapons such as explosives, were being uploaded online. To counter this threat, Xinjiang's internet guardians have been actively scanning the internet for suspicious materials and activities.

This is one of many stories in CGTN's exclusive documentary "The war in the shadows: Challenges of fighting terrorism in Xinjiang." Watch the full documentary here.