John Robb’s The Coming Urban Terror warns that cities are the battleground of the 21st century. Economic structures in cities are extremely vulnerable to attack and collapse.

Centralized governments are unable to defend urban economies. Robb advises Americans to decentralized their security and government services to better withstand the coming storm.

First, economies organized into a scale-free network. This means major transportation and communication hubs can be targetted to shut down entire networks:

Most of the networks that we rely on for city life—communications, electricity, transportation, water—are overused, interdependent, and extremely complex. They developed organically as what scholars in the emerging field of network science call “scale-free networks,” which contain large hubs with a plethora of connections to smaller and more isolated local clusters. Such networks are economically efficient and resistant to random failure—but they are also extremely vulnerable to intentional disruptions, as Albert-Laszlo Barabasi shows in his important book Linked: The New Science of Networks. In practice, this means that a very small number of attacks on the critical hubs of a scale-free network can collapse the entire network. Such a collapse can occasionally happen by accident, when random failure hits a critical node; think of the huge Northeast blackout of 2003, which caused $6.4 billion in damage.

Further, the networks of our global superinfrastructure are tightly “coupled”—so tightly interconnected, that is, that any change in one has a nearly instantaneous effect on the others. Attacking one network is like knocking over the first domino in a series: it leads to cascades of failure through a variety of connected networks, faster than human managers can respond.

Cascade failures are our nightmare. The US economy is hyper-specialized. Shutting down a few key parts will bring our economy to a standstill.

Countries in the third world are even more vulnerable. Their infrastructure and services are more antiquated and corrupt. These countries already face a high rate of random errors and failures in their economy. A series of coordinated attacks will shut down these economies and paralyze their governments.

This has been the insurgent strategy in Iraq:

The ongoing attacks on the systems that support Baghdad’s 5 million people illustrate the vulnerability of modern networks. Over the last four years, guerrilla assaults on electrical systems have reduced Baghdad’s power to an average of four or five hours a day. And the insurgents have been busily finding new ways to cut power: no longer do they make simple attacks on single transmission towers. Instead, they destroy multiple towers in series and remove the copper wire for resale to fund the operation; they ambush repair crews in order to slow repairs radically; they attack the natural gas and water pipelines that feed the power plants. In September 2004, one attack on an oil pipeline that fed a power plant quickly led to a cascade of power failures that blacked out electricity throughout Iraq.

Lack of adequate power is a major reason why economic recovery has been nearly impossible in Iraq.

It’s not just insurgents and religious fundamentalists. Criminal gangs are growing bolder. Gangs like the Red Command and the PCC have made Rio de Janeiro and Sao Paulo the most dangerous cities in the Western Hemisphere.

Another growing threat to our cities, commonest so far in the developing world, is gangs challenging government for control. For three sultry July days in 2006, a gang called PCC (Primeiro Comando da Capital, “First Command of the Capital”) held hostage the 20 million inhabitants of the greater São Paulo area through a campaign of violence. Gang members razed police stations, attacked banks, rioted in prisons, and torched dozens of buses, shutting down a transportation system serving 2.9 million people a day.

The RC shut down Rio de Janeiro soon afterwards.

The RC and PCC had no political platform or demands. They disrupted entire cities and shut down government and economic services – just to prove they can. They tested the strength and response time of the government, and must have liked what they found. Brazil’s gang war problem is getting worse.

Robb, like myself, sees Iraq as the Spanish Civil War of our time. It’s a test platform for new tactics and strategies for future wars. Right now, Iraq is the main battleground between rival ideologies – and the victor will gain a massive advantage in the near future.

The threat is two fold. First, criminal gangs, terrorists, and small insurgent groups will erode the foundation of the state through small but repeated attacks. Second, there will be far more powerful attacks in the future as the more sophisticated groups use chemical and biological weapons.

Non-state actors are already using chemical WMDs. Al-Qaeda in Iraq has made use of chlorine bombs, which is the obvious first step. A Japanese cult produced Sarin nerve gas and used it on a subway line. This will grow easier to do over time. Chemical weapons are the poor man’s WMD right now. It’s still a local weapon which is not much more useful than conventional explosives.

Biotech will be worse.

In fact, the curves of improvement that we see in biotechnology mirror the rates of improvement in computing dictated by Moore’s Law—the observation, borne out by decades of experience, that the ratio of performance to price of computing power doubles every 24 months. This means that incredible power will soon be in the hands of individuals.

In less than a decade, then, biotechnology will be ripe for the widespread development of weapons of mass destruction, and it fits the requirements of small-group warfare perfectly. It is small, inexpensive, and easy to manufacture in secret. Also, since dangerous biotechnology is based primarily on the manipulation of information, it will make rapid progress through the same kind of amateur tinkering that currently produces new computer viruses.

Most individuals will do good with this power. Our generation will deal with a biotech revolution – and the violence that accompanies it.

Our gravest problem are failed cities, perhaps even more so than failed states. Non-state actors are moving into the cities and are taking control. It gives them defensive cover and the city is vulnerable to systemic disruption.

I don’t mean to sound alarmist, but at this point in time, it feels like 1907 – just a few years before the storm, when everyone was still in denial.

Over the past century, economic growth and sophistication has been nurtured and protected by a thin red line of American soldiers. Behind that wall was security and prosperity.

Today that wall is gone, in part because of globalization, immigration, and new technologies. Without a wall, the military is forced to defend the global economy in an increasingly ad-hoc way against undefined non-state threats. If the military slips up even slightly, globalization will come to an end and Americans will be impoverished.

There are a number of military and security experts telling the public the same story – we can’t hold.