Secure the US against bloodless terrorist warfare

America's greatest failure in the years leading up to the Sept. 11 attacks was one of imagination - failing to imagine how terrorists might turn jetliners into flying missiles or box cutters into lethal weapons. The world cannot afford to make such a mistake twice.

And yet, four years after the worst terrorist attacks in modern memory, greater resolve is needed to counter and prepare for what is perhaps the terrorists' ultimate use of weapons against Western civilization - a bloodless attack aimed at disabling large segments of the highly interdependent infrastructure on which our societies depend. One method of delivering such warfare: detonation of a nuclear weapon at high altitude, causing an electromagnetic pulse (EMP).

EMP attacks are the result of a nuclear explosion's fission chain reaction interacting with the earth's magnetic field and ionosphere to electromagnetically shock any system conducting electrons. Even a small, unsophisticated nuclear weapon set off in space could destroy any system dependent on electricity or the flow of electrons, transforming conducting wires into large antennas that magnify the pulse's electromagnetic shock before destroying the hard wire's ability to conduct.

Systems running on large computer banks like Supervisory Control and Data Acquisition (SCADA) modules that manage electricity grids, power stations, air traffic control, electronic banking, railway directional indicators, dam doors, and water treatment plants, among others, would be severely affected. Any computer or microprocessor within a 200-mile radius of the blast would probably be destroyed, along with all its data. Cars and trucks wouldn't start, making it impossible to move food, fuel, and other vital necessities of everyday life. Backup generators would be rendered useless, affecting primary care facilities like hospitals and clinics.

EMP effects would be magnified by the codependencies in our SCADA systems - power loss affecting telecommunications systems upon which banking transactions rely, for example. Vulnerability to these cascading effects was seen during hurricanes Katrina and Rita late last year where a major American city came to a virtual standstill. As we are now seeing, it would take years to rebuild.

Our enemies know this. Having perfected the art of living in caves with little or no technology, they relish the thought of disabling Western societies built on electronic backbones of Internet communications and digitized computer frameworks. Killing innocent civilians, such as those who died at a wedding reception in the recent Jordanian hotel attacks, is costing the terrorists their political clout with increasingly disillusioned followers. Destroying the West's infrastructure without direct and immediate loss of life might galvanize their power base and be seen as an irreversible contribution to their vision of bringing about an apocalyptic end to Western civilization.

Evidence is mounting that EMP weapons have caught the eye of countries with clandestine nuclear weapons programs, and equally nefarious geopolitical agendas. Earlier this year, Iran exploded its Shahab-3 long-range ballistic missile in mid-flight by what appeared to be a pre-timed self-destruct mechanism, according to Jane's Missiles and Rockets. Why? Perhaps to test a delivery vehicle for launching an EMP weapon.

In the reemerging nexus between states and terror groups, Al Qaeda could play an all-important role in EMP attacks as well. An Iranian-made nuclear warhead attached to a Scud missile bought from North Korea for the paltry sum of $100,000 would be ideally suited for launch from an oceangoing freighter, of which Al Qaeda owns a number. A nuclear-tipped Scud launched from a freighter anchored off the US coast near a major metropolitan city would unleash catastrophic consequences if successfully detonated.

Last year, a group of experts came together to study the potential ramifications from an EMP attack on the US and other technologically advanced areas and recommended an array of proactive measures. They concluded that if SCADA modules were "radiation hardened" at the time the units were designed and manufactured, unit prices would rise by only 1 to 3 percent. In cases where retrofitting is the only viable solution, the costs are still a fraction of the price that would result from electromagnetic pulse damage.

Other measures include electromagnetic shields that harden electricity-producing infrastructure in major urban centers. Electronic wiring in centers of commerce, like the New York and London Stock Exchanges, or retail banks, should also be hardened against EMP.

Backup systems, whether large turbines, high-voltage transformers, generators, computers, or the wiring needed to run and connect them to unaffected functioning systems, should be stored in specially constructed radiation-hardened bunkers for immediate deployment in the unlikely event of a successful EMP attack. Circuit breakers that prevent immediate cascading effects over an entire network of telecommunications or electricity supply also need to be tested and put in place.

At a structural level, accelerating the development of a global missile defense system should become a priority. Destroying an armed missile launched for potential EMP detonation before it reaches the critical height where it can do its damage may be the ultimate countermeasure of choice.

Reducing both the real and perceived vulnerabilities of our power and telecommunications systems to an EMP threat will lessen the willpower of our enemies to undertake such a potentially devastating attack. We cannot afford to be lacking in imagination again.

• Mansoor Ijaz, chief executive of Crescent Technology Ventures PLC, negotiated Sudan's offer of counterterrorism assistance to the Clinton administration in April 1997. Lt. Gen. James Abrahamson (USAF Ret.) was director of President Ronald Reagan's Strategic Defense Initiative from 1984 to 1989 and remains involved in related US security efforts.