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.

Iraq is a petri dish for modern conflict, the Spanish Civil War of our times. It’s the place where small groups are learning to fight modern militaries and modern societies and win.

... New communications technology, particularly cell phones, makes it possible for gangs to thrive as loose associations, and allowing a geographical and organizational dispersion that renders them nearly invulnerable to attack. The PCC has been particularly successful, growing from a small prison gang in the mid-nineties to a group that today controls nearly half of São Paulo’s slums and its millions of inhabitants. An escalating confrontation between these gangs and the city governments appears inevitable.

... Picture a Russian biohacker who, a decade from now, designs a new, deadly form of the common flu virus and sells it on the Internet, just as computer viruses and worms get sold today.