Concerns are rising about the threat of an EMP (ElectroMagnetic Pulse) attack, aimed at destroying our electronic guts. What if our computers and other electronics didn't work? What if electronic records of your bank account were immobilized? What would happen to our technology—dependent transportation, financial, and production systems?

America's vulnerability to EMP (ElectroMagnetic Pulse) attack looms large in the minds of many. Public attention was focused on the topic by the release in 2005 of a government—sponsored study by the congressional Commission to Assess the Threat to the United States from Electromagnetic Pulse Attack. The results were further publicized by Frank J. Gaffney in a widely—read article, 'EMP: America's Achilles' Heel',а and was also featured in his recent book, War Footing —10 Steps America Must Take to Prevail in the War for the Free World.

Just last week Col. Gail 'Wojo' Wojtowicz, the Air Force's chief of future concepts and transformation, gave a public briefing on the problem. 'The one thing that makes me lose sleep,' Col. Wojtowicz said, 'Is an E—bomb, an EMP.'

EMP is an effect created by setting off a nuclear explosion at extremely high altitudes. In striking the upper atmosphere, the explosion's initial gamma—ray burst creates high—energy electrons (through a phenomenon called 'Compton scattering') that become trapped in earth's magnetic field, generating a pulse of electromagnetic energy.

This pulse can be powerful enough to cover an entire continent, and is extremely dangerous for all types of electronic equipment. Heavy voltage surges in metal objects, including cars and aircraft, can burn out internal electronics and render them inoperable. Power and communications lines act as antennas, generating an induced electric current more powerful than a lightning bolt. Any electronics equipment (and most electrical equipment of any type) hooked up to the power or phone grids would be immediately destroyed, including all types of computing devices and the data they contain. An EMP strike might not, as some claim, force the U.S. back into the 19th century, but it's not something you'd enjoy living through.

EMP was discovered as a byproduct of the Starfish Prime nuclear test on July 9, 1962. A 1.5 megaton bomb set off 240 miles over the Central Pacific blew up street lights and TV sets in Hawaii 1,000 miles away, created a mock aurora visible even further, and destroyed a number of orbiting satellites, including the Telstar I, the pioneering telecommunications satellite.а

In short order, nuclear attack plans were modified to commence with an EMP strike over enemy territory. Military electronics underwent a hardening process with the development of chips and other components resistant to EMP. Today even military jets and missiles are constructed to withstand the effect. (The same processes would work for civilian application as well, but in most cases would be prohibitively expensive.)

Evidence exists of keen interest in EMP by terrorists and their allies. Iran has tested versions of its Shahab missiles in trajectories ending in midflight explosions, exactly as would be expected of an EMP strike. Launches have also been made from shipboard, a method useful in attacking the continental United States. A correspondent who often posts EMP—related material on his website tells me that he sees a rash of Iranian IP addresses every time new material appears.

Yet all the same, it's unlikely that EMP represents a major terrorist—related threat to the United States, or will at any time over the next decade. EMP is a national weapon, a weapon that can be used only in cases of total war — and also, at the moment, a weapon effectively beyond the reach of anyone outside the major members of the nuclear club.

Technical requirements for an EMP attack are extremely steep. To achieve continent—wide coverage, a warhead needs to be lofted to an altitude of over 200 miles at a point directly over Kansas, a distance of 1500 miles from the East Coast. This would require a booster of the Intermediate Range Ballistic Missile (IRBM) class, which is one step above the Shahab series. The latest model, the Shahab 4,а with a range of 1200 miles, is almost capable of such a mission, but without a full 2,000 lb. warhead.

Another complication is that high—altitude EMP requires a weapon in the megaton range. (Cold War scenarios utilized a top—of—the—line 20—megaton bomb.) These are thermonuclear weapons, hydrogen bombs, which terrorists and associated states do not yet have. It requires an extremely advanced industrial plant to construct such a weapon. The U.S. can do it, as can the Russians and Chinese. The Iranians cannot. Their first nuclear weapons, if they're allowed to build them, will be simple fission weapons of a relatively low yield.а

EMP can be achieved by fission weapons at a much lower altitude. (The effect begins to pay off at roughly 19 miles.) Such an attack would be far less destructive than a high—altitude strike, with effects limited to a radius of 250—300 miles. To achieve useful results, something on the order of a dozen launches would have to be made, on both east and west coasts along with the Gulf of Mexico. This is an extremely complex operation in which each part has to operate with clockwork precision. And even at best, some areas would be left untouched.

In fact, the universal collapse envisioned as a result of a high—altitude EMP strike may be impossible in any case. The situation has never been tested. The Starfish Prime results were an accident, one that has never been repeated. No further tests could be made due to the Comprehensive Test Ban Treaty, which forbade weapons tests in the atmosphere or outer space, going into effect shortly afterward. Much of what we think we know about EMP lies in the realm of theory, with little in the way of hard evidence. Some scientists believe that the effect has been overrated. These include electromagnetic specialist Dr. William A. Radasky, who thinks that disruptions would be minor and temporary. The pulse could very well be attenuated by distance and other factors, some of which may be completely unknown to us at this time. Mountain ranges such as the Rockies and the Sierra Nevadas could provide considerable protection, along with various deep valleys around the country.

And in any case, the collapse would be well short ofа 'universal'. Even if everything went according to plan, Hawaii, Alaska, Puerto Rico, Guam, Gitmo, and all the fleets and overseas bases would still be intact. In the worst case, the U.S. would remain a reigning military power. And with only a handful of suspects, it would not be long until the troops paid a visit to the guilty party.

That wouldn't bother Osama bin Laden — he's never shown a sign of caring one iota who suffers as a result of his plans. But what about the ayatollahs? With the example of the Taliban right next door, how eager would they be to set themselves up as targets? It can be argued that as 'Twelvers' they'd welcome the Apocalypse rather sooner than later. But if that's the case, their recent behavior — turning Ahmedinejad loose to caper and bellow, uttering threats in every direction, boasting of possessing weapons they have no means of developing — gives no indication of it. If anything, the exact opposite. The ayatollahs are acting like men running scared, without a single touch of the icy serenity that reveals the true fanatic.

An EMP strike not backed up by other action, along the lines of a full—fledged nuclear attack, might succeed only in unleashing surviving elements of American power — which would be more than enough to throw any possible opponent back into the dark ages. So it may well be that EMP, like nuclear weapons themselves, is a weapon that, however tempting it appears, no country can afford to use. Deterrence may still be the last word.

Not that we can depend on that alone, not in the long run. Any possibility, however remote, of the country being crippled with one blow should not be endured for a moment longer than necessary. This is a situation where Ballistic Missile Defense (BMD) offers a near—perfect countermeasure. None of the standard objections — that BMD can be 'overwhelmed' by thousands of missiles or decoys — is operative here. Nobody could launch thousands of missiles from shipboard, and decoys can't practically be deployed during a missile's boost phase. (The same applies to stealth technology, useless when coupled with a rocket engine blazing like a house afire.)

We require a network of missile sites along the coast, ready to launch immediately on detecting an attack (which can't possibly be mistaken for anything else). While we do possess sixty—odd Aegis—class warships capable of engaging ballistic missiles, they have other duties. The solution would be to place Aegis systems on the coast as a gap—filler until the Patriot follow—on, now being developed with the cooperation of Japan and several European countries, comes online in 2014. (It wouldn't be a bad idea to hurry that model along, either.)а

It would also be wise to implement some of the recommendations of the EMP
commission, including stockpiling spare parts for critical machinery and looking into reports that the military has, since the Cold War, been sliding on equipment requirements. (Individuals can also take steps to protect their personal data, an effort which, with items such as flash drives,аis getting cheaper all the time. A flash drive stored well away from any external electrical lines would very likely survive an EMP strike.)

Above all, we can't allow the problem to slip past without being addressed, always a danger in a confusing and urgent time. Threats have a way of sneaking up on democracies. Back in the 70s, an American president, on the promise of the Soviet premier that no aerial attack would be carried out on the U.S., decided to shut down the Aerospace Defense Command and its U.S. Army equivalent responsible for air defense of the country. The bases were closed, the assets either scrapped or turned over to the National Guard. Two decades later, on a fine morning in September, there were no alert squadrons, long—range interceptors, or surface—to—air missiles to defend New York and Washington.а

The president's name was Jimmy Carter. We can do better.

J.R. Dunn is the author of a landmarkаthree part series on the futureаstrategies of jihad terrorism. Among many other things, he was editor of the International Military Encyclopedia for twelve years.