Five years ago Josh Chin was driving with a colleague outside of Korla, the second-largest city in China’s Xinjiang region, when they found themselves on a winding dirt road. A cloud of dust formed, and when it cleared, one police car was in front of them and another was behind them. 

Several officers, some carrying assault weapons, surrounded the car, gestured for them to get out and interrogated them about what they were doing in the area. After persuading the police officers to let them go, Chin asked one of them how they had found them in the first place. 

“We have cameras back there,” Chin recalls the officer saying. “One of them recognized your license plate.”

Such advanced surveillance has become the norm in Xinjiang and around the country, according to Chin’s new book, “Surveillance State: Inside China’s Quest to Launch a New Era of Social Control,” which he co-wrote with his Wall Street Journal colleague Liza Lin.