In the wake of the Islamic State's defeat in Mosul, the fight between the organization and its adversaries has reached an inflection point. Over the past week, credible reports from Mosul — sometimes accompanied by purported video and photographic evidence — have indicated that members of the Iraqi Security Forces are conducting mass executions of Islamic State members and their families, along with suspected civilian affiliates. In Raqqa, Syria, similar reports have appeared alleging that members of the U.S.-backed Syrian Democratic Forces are abusing and executing Islamic State prisoners....
