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.
Unfortunately, the improvements in lethality that we have already seen are just the beginning. The arc of productivity growth that lets small groups terrorize at ever-higher levels of death and disruption stretches as far as the eye can see. Eventually, one man may even be able to wield the destructive power that only nation-states possess today. It is a perverse twist of history that this new threat arrives at the same moment that wars between states are receding into the past. Thanks to global interdependence, state-against-state warfare is far less likely than it used to be, and viable only against disconnected or powerless states. But the underlying processes of globalization have made us exceedingly vulnerable to nonstate enemies. The mechanisms of power and control that states once exerted will continue to weaken as global interconnectivity increases. Small groups of terrorists can already attack deep within any state, riding on the highways of interconnectivity, unconcerned about our porous borders and our nation-state militaries. These terrorists’ likeliest point of origin, and their likeliest destination, is the city.
Cities played a vital defensive role in the last major evolution of conventional state-versus-state warfare. Between the world wars, the refinement of technologies—particularly the combustion engine, when combined with armor—made it possible for armies to move at much higher speeds than in the past, so new methods of warfare emphasized armored motorized maneuver as a way to pierce the opposition’s solid defensive lines and range deep into soft, undefended rear areas. These incursions, the armored thrusts of blitzkrieg, turned an army’s size against itself: even the smallest armored vanguard could easily disrupt the supply of ammunition, fuel, and rations necessary to maintain the huge armies of the twentieth century in the field.
To defend against these thrusts, the theoretician J. F. C. Fuller wrote in the 1930s, cities could be used as anchor or pivot points to engage armored forces in attacks on static positions, bogging down the offensive. Tanks couldn’t move quickly through cities, and if they bypassed them and struck too deeply into enemy territory, their supply lines—in particular, of the gasoline they drank greedily—would become vulnerable. The city, Fuller anticipated, could serve as a vast fortress, requiring the fast new armor to revert to the ancient tactic of the siege. That’s exactly what happened in practice during World War II, when the defenses mounted in Leningrad, Moscow, and Stalingrad played a major role in the Allied victory.
But in the current evolution of warfare, cities are no longer defensive anchors against armored thrusts ranging through the countryside. They have become the main targets of offensive action themselves. Just as the huge militaries of the early twentieth century were vulnerable to supply and communications disruption, cities are now so heavily dependent on a constant flow of services from various centralized systems that even the simplest attacks on those systems can cause massive disruption.