The Coming Urban Terror - John Robb, City Journal.

For the first time in history, announced researchers this May, a majority of the world’s population is living in urban environments. Cities—efficient hubs connecting international flows of people, energy, communications, and capital—are thriving in our global economy as never before. However, the same factors that make cities hubs of globalization also make them vulnerable to small-group terror and violence.

Over the last few years, small groups’ ability to conduct terrorism has shown radical improvements in productivity—their capacity to inflict economic, physical, and moral damage. These groups, motivated by everything from gang membership to religious extremism, have taken advantage of easy access to our global superinfrastructure, revenues from growing illicit commercial flows, and ubiquitously available new technologies to cross the threshold necessary to become terrible threats. September 11, 2001, marked their arrival at that threshold...