A prefecture in China’s far western Xinjiang region is requiring all vehicles to install satellite tracking systems as part of stepped-up measures against violent attacks. Traffic police in Bayingolin Mongol Autonomous Prefecture announced the regulation on Sunday, shortly after thousands of heavily armed police paraded in the Xinjiang capital and ruling Communist Party officials vowed to ramp up their campaign against separatists and Islamic militants. The vehicle-tracking program in Bayingolin will utilize China’s homegrown Beidou satellite system, launched in recent years to reduce China’s reliance on U.S.-based GPS providers for sensitive applications. Authorities said they will also track cars using...