In the last two years, “lone wolf” jihadists seemed to emerge as the new face of terrorism. In December 2015, husband and wife Syed Rizwan Farook and Tashfeen Malik attacked a Christmas party held by Farook’s employer, the San Bernardino County Department of Public Health, killing 14. In June 2016, Omar Mateen killed 49 people at a gay nightclub in Orlando, Florida—the deadliest attack on U.S. soil since 9/11. And in July, Mohamed Lahouaiej Bouhlel drove a truck through a Bastille Day celebration in Nice, killing 86 people. The attacks by the San Bernardino killers, Mateen, and Bouhlel followed an increasingly common pattern: the Islamic State (also known as ISIS) claimed credit for them, but the perpetrators appear to have planned and executed their operations alone.
Analysts traditionally define a lone wolf as a terrorist who is not part of a group or directed by an outside organization. In reality, few lone wolves truly act alone: Farook and Malik were a married couple, and some security officials believe that Bouhlel had been in contact with suspected extremists in his neighborhood. Nevertheless, the label is important: terrorists who act without external guidance pose a different threat, and call for a different policy response, than do those who are directed by an extremist group.
Lone wolves are an old problem, but in recent decades, the number of attacks by them has grown. And it won’t fall anytime soon: ISIS has embraced the tactic, and recent successes may well inspire copycats. And although lone wolves usually kill few people, they have an outsize political impact. In both the United States and Europe, they are fueling Islamophobia, isolating Muslim communities, and empowering populist demagogues.
Although lone-wolf attacks are hard to prevent, governments in the West can do several things to make them less likely and to prepare for those that do occur. First, they should work to keep lone wolves isolated. Terrorists are far more likely to succeed if they can coordinate with others, especially if