Countries rely on computer infrastructure for a huge percentage of communications and military management, as well as utilities like electricity. Unfortunately, nuclear attacks release massive electromagnetic pulses that damage these systems.

Normally this isn't much of an issue, since everything in the pulse radius is reduced to ash, but high-altitude nuclear explosions (HANE) can cause serious electronic damage without the hassle of mass death and destruction.

Ignoring the ridiculous improbability, I'd like to know how infrastructure critical to a nation during wartime might be secured against such damage. Since this is purely theoretical, I'd like to see sources for all information. I don't mind what countries you focus on, as a nuclear war is likely to affect all of them.

I know this is a pretty outlandish question, but it's been on my mind for a while and I'd love to see some well-sourced answers on the subject.

P.S. Yes, I did just find a legitimate use for the tag.

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    If I were really looking to create my own hyper-resilient network, I would just use the standard DNS system which is already globally resilient to numerous forms of attack, including localised blackouts from disasters and military strikes. If the fact that I'm not looking to actually create such a system eludes you, you've clearly got some serious comprehension issues. This is a theoretical question, for nothing more than academic purposes. People come to Sec.SE to learn, not be fed opinion.
    – Polynomial
    Aug 13, 2012 at 15:58
  • For context, the above comment was in reply to a comment that has since been deleted.
    – Polynomial
    Aug 13, 2012 at 18:27
  • There's a risk of EMP damage from solar flare activity. But I couldn't say how likely this is.
    – symcbean
    Aug 13, 2012 at 22:30
  • The ionosphere does a good job of deflecting most of it, and the water in our atmosphere absorbs a lot too. It'd have to be one hell of a solar flare to induce significant currents in ground-level wiring.
    – Polynomial
    Aug 13, 2012 at 22:37
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    The solar flare of 1859 is recorded to have disrupted telegraph. A smaller one in 1989 triggered a 9-hour blackout in the province of Québec, and yet another a few months later blocked Toronto's stock exchange for three hours (apparently by killing off harddisks). Aug 14, 2012 at 0:56

7 Answers 7


The Internet at large is designed to resist nuclear blasts. At least, it was a design goal of its immediate predecessor, ARPANET.

There is no secret: to survive loss of components, you must have redundancy. In the context of nuclear blasts, this means that there must exist several paths for data between any two machines, and the paths should be as geographically separate as possible. Mathematically, given an assumed blast radius r of 50 miles (for a nuclear-powered EMP, this is a rather low estimate), and two machines A and B and two paths between A and B, then the following should hold: for any two points M and N where M is on path 1 and N is on path 2, and the distance between M and N is less than r, then either M or N (or both) is no farther than r from either A or B. In plain words, the two paths never come closer than 50 miles from each other, except at both extremities (the two paths necessarily join at A and B).

The packet routing nature of ARPANET, then the Internet, allows for such redundancy. Extra points to radio links, in particular satellites: the link between a base station and a satellite cannot be permanently disrupted by a nuclear blast in between. The blast may induce a high ionization of the upper layers of atmosphere, so communications may be temporarily jammed, especially for longer wave lengths; satellites work in the GHz band and should have less trouble than, say, FM. Also, geostationary satellites tend to be relatively high on the horizon (at least from southern USA -- much less so from, say, Moscow) so getting a blast between a base station in Atlanta and a geostationary satellite which is roughly over the Americas entails detonating the thing over US territory, at which point Atlanta itself is in big trouble.

Transoceanic cables should also be fine: 3 miles of water are a Hell of a shield. And they offer lower latency than geostationary satellites (the ping time with a remote server through a geostationary satellite cannot be lower than half a second, because 4*36000 = 144000 km); latency is a problem for flying drones. Lower-altitude satellites are more difficult to use (from the point of view of a base station, they move a lot and often go beyond the horizon) and are in range of Anti-satellite missiles.

Optic fiber is more resilient to EMP than copper links, and the US military have studied that for more than 35 years. The weak part of an optic fiber link would be repeaters: the devices which pick up the signal and re-emit it stronger. You need some of these in any long-range cable. But at least this reduces the problem to building anti-radiation bunkers at regular intervals.

Actually, a bigger problem may be electricity. An EMP will imply high surges in the grid. For instance, the US grid has trouble resisting bad weather.

And, of course, redundancy of network links is not sufficient: you also need to duplicate the servers (data storage, computing elements). You already need to do that to survive floods and earthquakes and even simpler events like a server room burning down. EMP resistance is just more of the same, on a slightly larger scale.

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    Couple points of clarification. First "Optic fiber is more resilient to EMP than copper links." I thought fiber was unaffected by EMP, not just more resilient? "Actually, a bigger problem may be electricity." Actually, this IS THE PROBLEM! Ask an electrical engineer what happens to the energy producing capability of anything effected by EMP (batteries, generators, anything electrical). I believe the term is "degaussing." Power can't be produced by eqpt that has been effected by an EMP because the magnets in generators have no polarity, and batteries are discharged. Period.
    – Everett
    Aug 13, 2012 at 16:39
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    @Everett: the fiber itself is unaffected, but the light-based signal is converted to electrical signals at both ends of the fiber, and also in repeaters. A totally optical system would resist EMP (except for its power supply) but photonic computing is still highly experimental and slow. In the mean time, regardless of how much fiber you use, there must still be silicon-based parts, which are vulnerable to EMP. Aug 13, 2012 at 17:10
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    @Thomas Pornin - I owe you an apology, I didn't consider the transition point. I'd remove my comment but I think it may help someone in the future (let me be dumb instead of them having to do it).
    – Everett
    Aug 13, 2012 at 17:22

While I dont know how most critical infrastructure is defended against EMP threats I do know of many instances of critical infrastructure offer no protection to these kinds of threats.

This does however not mean that there does not exist protection. Take for example Kelvedon Hatch nuclear bunker. Some of its features, and which should be considered in any preventive means against nuclear warfare:

  • It is 38 meter underground. Lead by a 120 meter long tunnel.
  • 1.5-tonne blast doors
  • Equipment for power generation
  • Air filtration and pressurization. It keeps a positive pressure level to prevent raidoactive gasses to enter.
  • Water supply from it's own bore hole
  • Communication equipment to communicate with other bunkers.
  • Broadcasting station for nationwide broadcast
  • Surrounded by a huge faraday cage to prevent electro magnetic pulses to enter.
  • Surrounded by 3 meter thick walls
  • The top of the bunker is covered by concrete

Some details about the farday cage. It exists to divert electric pulses in the air into ground instead of into computer equipment. The cage absorbs all the electric signals. You have this in your microwave aswell, and I have it in my wallet to prevent RFID leakage. The reason for the blast to create an EMP is caused by the air becoming ionized with electrons from the nuclear blast (gamma radiation).

Source: Wikipedia, The Geek Atlas

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    The Cheyenne Mountain NORAD bunker is famous for that, too; it is designed to survive a direct hit from a nuclear weapon, even if the Commies actually come to the site and bury the warhead right above it. Aug 13, 2012 at 15:23
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    "it is designed to survive a direct hit from a nuclear weapon" of the caliber that existed when it was designed. If it was hit by anything in current inventory, it would not survive. This is why it has been decommissioned (isn't used for that purpose anymore).
    – Everett
    Aug 13, 2012 at 16:48
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    @ThomasPornin That's just what they want you to believe. It's really the bunker where they keep the Stargate ;)
    – Polynomial
    Aug 13, 2012 at 17:13
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    @Everett: this is arguable; the largest nuclear blast ever performed is the Tsar Bomba and it was in 1961, the year the Cheyenne Mountain bunker building started. Newer designs are actually less powerful, and that's voluntary: low-power nuclear blasts have a high tactical value, as opposed to massive H-bombs which are for my-nuke-is-bigger contests (also known as "dissuasion"). Aug 13, 2012 at 17:16
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    @ThomasPornin what's changed since the early 1960's is accuracy. At that time an ICBM had an typical guidance error of a mile or two. Current accuracy for ICBMs is typically reported in the 10-100m range (exact numbers are classified), and cruise missiles can hit more closely than that. The inverse square law means that smaller modern weapons will deliver significantly more energy to the blast doors that the older giant ones. Even before then, the Soviets had at least 20 ICBMs carrying a 20MT warhead. Most of them were targeted to excavate Cheyenne Lake as NORADs grave marker. Aug 13, 2012 at 20:15

Electro-magnetic pulse is mostly mitigated by sending it to ground.

  1. Place routers/firewalls in a faraday cage (Imagine a room that has copper screen on all sides of it).
  2. Ground the Faraday cage (connect the copper mesh to multiple 6' copper rods that are pounded into the ground).
  3. Make it level with the ground (using the earth to block some of the EMP blast).
  4. Have no way for the EMP to enter the room (these devices weren't connected to power, use fiberoptic cable as the signal path).

This would electrically isolate the equipment. The only way I could think of to power it is to have generators that can handle the electrical load of these devices in the room as well. Once the pulse has fired, you can hook the eqpt to generators, start them, and recover your network. However, any computers/storage devices on this network that need to be functional would have to have been in a Faraday cage as well.

I don't think the government is going to publish data that shows whether or not it is ready for EMP blasts.

You can generate an EMP blast without a nuclear detonation (just so you have more to worry about).




  • Second, EMP. Electro-magnetic pulse is negated by sending it to ground - erm sort of - the problem is that if the pulse is large enough it's just not possible to ground enough of the current to avoid damage - even inside a faraday cage you can pick up radcast radio waves with sufficiently sensitive equipment
    – symcbean
    Aug 13, 2012 at 22:54
  • @symcbean - Absolutely true. I should have stated that the precaution of being at (actually below, I mean the ceiling is at) ground level would help mitigate that as well. Making an edit to address this.
    – Everett
    Aug 13, 2012 at 22:56

The U.S. government for many years has had a program called TEMPEST. Originally it was a set of specifications for devices and structures intended to minimize the chance of an outside evil-doer picking up emissions from devices processing sensitive data.

Over the years it has extended to EMP protection. This is logical since those measures that keep emissions 'in' will also keep emissions 'out'.

Google TEMPEST EMP and you'll see a lot of interesting information on this subject.

  • 1
    My favourite backronym for TEMPEST has to be Tiny ElectroMagnetic Particles Emitting Secret Things.
    – Polynomial
    Aug 13, 2012 at 17:10

Think old-school. Vacuum tubes. Transistors and other semiconductors will likely be damaged by the induced voltages of the EMP, and few consumer or industrial grade chips are hardened against this kind of damage. Look at static electricity damage under a microscope some time and you'll see what happens when only a few hundred volts pass through a chip. Even when the chip isn't outright destroyed, it's often damaged to the point where a failure is in its near future.

But vacuum tubes will continue to work. Even if it were to internally arc due to kilovolts of overvoltage, it won't necessarily be permanently damaged.

So make friends with an old HAM. When the EMP hits, he'll be the only one talking to the rest of the world.


A little googling turned up this page: http://standeyo.com/News_Files/NBC/EMP.protection.html There seem to be two basic options for protecting electrical equipment:

  • Faraday cage
  • Ovonic threshold device

If I remember correctly, a Faraday cage can protect against EMP like threats.

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