A Pew survey published on August 1, 2017, found that the fear of an attack by the so-called Islamic State (IS) ranked first in global concerns, just above climate change. The fact that the threat from a marginal and declining group of a few thousand members could worry people more than a threat that will affect the lives of everyone in the world — and for the foreseeable future3— is testimony to the power of terrorism and to the particular ability of IS to horrify. But although the fear of terrorism is disproportionate to the threat, there is unfortunately little doubt that IS, or something similar will survive the worldwide campaign against it. There is little predictable about the trajectory of terrorism in a world in flux, except that it will continue to challenge international security for many
years to come…