A Dec. 1 attack in Pakistan's Khyber-Pakhtunkhwa province that killed nine was the area's worst terrorist incident since 2014, when militants killed 132 children and nine adults at a primary school in Peshawar. Outrage over the children's deaths proved to be, in the words of Pakistani BBC analyst Aamer Ahmed Khan, "a watershed for a country long accused by the world of treating terrorists as assets." The newly elected provincial government, under a reformist party called Pakistan Tehreek-e-Insaf, or "Movement for Justice," struck back. It did not use drones or massive assaults to deal with the crime. Instead, it used old-fashioned police work....