Charlie Winter, a London-based terrorism researcher, was dining with friends one recent evening when the conversation turned to whether it is ethical to eat meat.
Someone brought up slaughterhouse conditions, Winter said, and he instantly grew uneasy. He stayed for a while longer, squirming, and then finally left the room. That word — "slaughterhouse" — had conjured images of one of the most gruesome ISIS videos he'd come across. The militants had filmed a mass execution in a slaughterhouse, casting their prisoners as the animals.