In the past we've posted on the potential threat posed to our nation by the detonation of a nuclear weapon high in the atmosphere. Such a blast, we noted, could release a pulse of gamma radiation that would effectively knock out all of our electronics across the entire continent with devastating consequences to every sector of society. It would effectively bring our nation to its knees.
Now J.R. Dunn in The American Thinker gives us reason not to lose too much sleep over the prospect. After summarizing how EMP (electromagnetic pulse) weapons would work he discusses why they are probably not the immediate danger that some analysts feared:
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, 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.
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....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 of "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.
Dunn finishes his essay with a plea for ballistic missile defense, just in case. Better to have it and not need it, than to need it and not have it, we say.