If you read that report, they got it from a fictional book titled “One Second After”
What part of the electrical grid is damaged by an EMP, and how long would it take to repair?
I’m not sure anyone really knows definitively, but there are educated guesses on the subject. The Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack says
If the power were out in 70% of the country for months / years, life would be a mess.
The JASON Advisory Group report on vulnerability of the US electrical power grid by space weather (JSR-11-320, “Impacts of Severe Space Weather on the Electric Grid”, The MITRE Corporation JASON Advisory Group, November 2011) gives insight into how much damage a severe EMP attack could do and the time and expense to recover from it. Although the report is focused on massive geomagnetic activity caused by severe ionized solar radiation like that experienced in the 1859 Carrington Event, the E3 component of a large nuclear impulse EMP (using a multimegaton nuclear weapon optimized for X-ray output) would be similar.
How much resulting damage would this do to the electrical grid and industrial infrastructure? I think most people do not realize the extent to which modern civilization is heavily dependent upon electricity and EMP-sensititive technology for essentially all facets of modern life including food production and transportation, water treatment, communication for public safety and law enforcement, et cetera. Without even minimal electrical power production and transportation, major cities would rapidly become uninhabitable. Similarly, we’d have difficulty harvesting crops, processing and transporting food, et cetera. With an EMP attack, it is likely that most devices reliant on modern microelectronics (virtually all vehicles, many appliances, essentially all cellular and digital communications, et cetera) would be permanently disabled and requiring replacement, so even assuming that workarounds would be possible to keep an ad hoc power distribution capability working there are still major problems to deal with.
However, an estimate of 90% fatalities, or even 50%, is vastly overstating both the immediate and long term impacts, although the potential for civil unrest and deaths due to internal strife and insurgency could certainly compound the problems causing larger scale famine and disease by interfering with efforts to provide needed food and basic medical and sanitation services. The impact of the loss of basic services will make itself felt to populations least able to be mobile and respond by evacuating to areas where logistics and civil protection is easier to provide; in other words, the elderly, indigent, and immobile will probably suffer large scale casualties. People who are capable of basic mobility and can be put to work doing manual labor for agriculture, construction, et cetera will probably experience much lower casualties provided that civil order can be largely maintained. I think any solid numbers are complete guesswork, but I personally think near term casualties would not exceed more than 10% of the population immediately, and the long term impact will heavily depend upon the degree of civil breakdown, ability of military organizations to protect critical civil structures and systems, and foreign aid from European and Asian industrial powers (provided they are not impacted by similar attacks), which is probably a good reason to not be snubbing Angela Merkel.
However, we’re talking about a coordinated attack using an advanced EMP weapon with an energetic yield on the order of 10 MT or larger. North Korea is nowhere near being able to either construct such a weapon, miniaturize it to fit into a flyable package, or deliver it to the correct location over the continental United States to conduct an effective attack or delivery simultaneous multiple attacks with smaller weapons. Practically speaking, even if the Hermit Kingdom could deliver some kind of smaller yield weapon it would only have regional impacts which would be enormously costly but would not result in either wide scale civil breakdown or loss of military response capability, and that would not be a good day to live on the Korean Peninsula. In some ways, it might be a good thing for the US in the long term because it would necessitate the replacement and upgrade of our badly obsolescent and largely ad hoc electrical distribution grid architecture with more efficient, robust, and easier to maintain components.
As for SDI, the Soviets had heavily invested in various aspects of ballistic missile defense systems in the 'Sixties and early 'Seventies, including nuclear interceptors, hit-to-kill interceptors, space based projectile weapons, and directed energy weapon research between competing design bureaus, and by all credible accounts came to the realization that ballistic missile defense against ICBM class targets beyond the point defense regime would be incredibly costly, difficult to establish a useful level of reliability or practical utility (especially lasers and space-based particle beam devices), and could be subverted by various inexpensive countermeasures. By the time Ronald Reagan made his infamous “Star Wars” speech, the Soviets were well aware of the unlikely practicability of any continental defensive system of the kind Reagan proposed, and were mostly concerned that the internal response would be internal political squabbling over how to respond. Economically, the Soviet Union had been moribund since at least the early 'Sixties (it arguably never recovered industrially from World War II, and was heavily dependent upon the Warsaw Pact “client states” to provide manufactured goods and sometimes even essential supplies). What destroyed the Soviet Union economically (and politically) was the Chernobyl disaster, rapid drop in petroleum prices in the early 'Eighties, the disastrous 1979 invasion of Afghanistan (engineered by Carter administration National Security Advisor Zbigienew Zbrezenski), and the massive massive expensive of the Soviet Buran shuttle program which had even less purpose or goal than the American Space Transportation System it was clearly intended to compete with. By the time Mikhail Gorbachev announced his “Sinatra Doctrine”, permitting the East Bloc states to separate from the Warsaw Pact and economic obligations to the Soviet Union, the issue of SDI was of essentially no consequence, and the Soviets did not significantly increase military spending to combat it beyond what they had already planned for missile system development prior to the Reagan administration.
Stranger
How much actual realistic defence do ground based systems give against even theatre level MIRV threats (China, India and Pakistan have all recently developed MIRV IRBMs) even limiting the protective umbrellas to high value targets like HQ’s and own offensive assets? Aegies and THAAD have been touted as having good ability against theatre level threats, how well would they do against MIRV or penetration aids?
Secondly, ground based systems seem to be basically an upgrading of SAMs. The highest kill rates that SAMs have ever achieved are ~15% in the early parts of the Oct 73 War on the Sinai front. Is it realistic to expect technology which is an evolutionary development of an existing one to have kill rates several fold higher than the parent technology has displayed?
It’s a minor terminology nitpick, but I believe you mean MaRV (Maneuverable Reentry Vehicle) rather than MIRV (Multiple Independently-targetable Reentry Vehicle). MaRVs to present a new challenge for defense as they are not strictly ballistic, but the primary purpose behind MaRVs is not active evasion (they cannot detect or deliberately avoid an interception) but to fly trajectories that are not possible ballistically, such as high altitude “waverider” cruising and then sudden terminal drop, or flight around obstacles to hit targets concealed in mountain ranges or canyonlands, or even active propulsion terrain-following flight in the terminal phase.
Penetration aids (inflatable decoys, radar-interfering chaff, and inert secondary RCS clones, often collectively referred to as “pen aids”) can be used to confused the ground or space based discrimination and tracking system which guides the interceptor to terminal locus where the local interception sensors take over. It is pretty easy to come up with a pen aid that can confuse even sophisticated system and almost impossible to anticipate how pen aids might look in the target scene until they’re actually observed in flight (either in testing or from an actual threat). Even if the pen aids aren’t particularly sophisticated or difficult to distinguish from the actual target they can generate enough “noise” in the signal to confuse the discrimination software or pollute the sensor image sufficient to cause the system to not perform as expected. In fact, in many tests, incidental debris from the booster or release systems can cause test failures even though it really looks nothing like the threat to human eyes. As the experience base has grown the discrimination software capability has become more robust and capable of making near-real time discrimination between threats and pen aids or debris, but it will remain a challenge for the defender to keep up with new ways of defeating the system with threat-like pen aids.
I can’t speak to how reliable these systems actually are, but I will say that the general trend in testing has gone from realistic development tests intended to punch the corners of the box to orchestrated scenarios design to maximize success of tests. It would be easy to blame the services involved for pandering for success, but in fact they’ve been criticized so often for “failing” in what should be regarded as development-level tests where failure is an expected and necessary part of the exercise of system improvement that they’re gunshy of adding genuine challenges to a system that has already been declared “fully operational” by executive management for purely political reasons.
Theatre anti-ballistic missile (ABM) systems are, of course, an outgrowth of surface-to-air (SAM) missile systems intended for anti-aircraft use (which the Patriot missile system was originally developed for before being retasked and eventually completely redesigned in the PAC-3 version for point defense ABM use) but the radars and tracking systems they use are significantly more sophisticated. Where an attack aircraft flies in relatively level flight at some air speed not far exceeding Mach 2 a human operator can make decisions about whether and when to release missiles. A ballistic missile is moving much faster, to the point that human intervention and designation is simply too slow. With an ABM system, you activate it and it looks for hypersonic speed ballistic threats, and then figures out how many interceptors to fire and when, essentially without human intervention.
We actually developed such systems in the 'Seventies for ICBM class threats; the Safeguard system used Spartan long range (late mid-course interception) and Sprint short range (terminal interception) interceptors; while these were nuclear tipped interceptors, with the Sprint one of the problems in testing was that it was actually physically intercepting the target rather than just flying close enough for the neutron emission from the warhead to damage the incoming RV. Of course, this was a multibillion dollar system suited only to point defense of a missile complex (the one completed system, the Stanley R. Mickelson Safeguard Complex protecting the Grand Forks AFB Minuteman Complex) with numerous radars, and was deactivated because of the costs to maintain the system functionality against more sophisticated attacks. We should be able to develop modern theatre defense ABM against fairly sophisticated purely ballistic and limited MaRV IRBMs using modern computing and software technology, and we absolutely need that capability because of the proliferation of that capability by many current and future threats, but it isn’t an easy problem and developing assurance that the system will function in the real world as intended requires extensive development testing and recognizing that failing tests in an inherent part of improving the system.
Stranger
Some data is confusing; some suggesting a primitive single-stage nuclear weapon generates EMP best, but other stuff suggests that the more powerful the better (i.e., multi-stage)? Is it because a single-stage weapon simply releases X-rays while the multistage weapon absorbs the primary’s X-rays into the secondary stage? But surely the 2nd stage emits plenty of X-rays of its own too?