(Economist) Since the outbreak of the "stabbing intifada" in late 2015, there have been hundreds of knife and car-ramming attacks against Israelis. If the violence has ebbed, it may be in part because the Israel Defense Forces (IDF) have become better at forestalling attacks. Israeli spooks reckon they have lessons to offer Western countries struggling to stop lone wolves. One is that conventional intelligence organizations, even Israel's well-honed system, are designed to penetrate organized terrorist groups, so they struggle to spot imminent attacks by self-radicalized individuals or small groups. After reviewing the profiles of scores of attackers, IDF intelligence officers found they often acted on the spur of the moment. They were rarely linked to militant factions, and were not especially religious or poor. Many had a grievance: a son who felt unjustly treated, a brother who was disinherited, a bride who was beaten by her husband, and so on. These days IDF algorithms monitor the social-media accounts of young Palestinians to look for early-warning signs. These include "tripwire" terms such as the "sword of Allah" or "day of the sword", associated with the writings of past attackers. The IDF also monitors the activity of relatives, friends, classmates and co-workers of recent "martyrs." The parents of those deemed suspicious might receive a telephone call or a visit from the Shin Bet security service, and their names could be passed on to the Palestinian Authority.