High Altitude EMP


Any nuclear detonation above 25 miles will cause a high altitude EMP (electromagnetic pulse).

A nuclear weapon detonated at an altitude of 200 miles could affect all unprotected electrical equipment within the continental United States.

Nuclear weapons at that altitude could be detonated from a satellite, an intercontinental ballistic missile, or from a ‘Scud’ type missile launched from a freighter. Depending on the location and size of the blast, the effect would be to knock out the power grid across most, if not all, of the continental United States.

It is believed that some terrorist organizations and numerous countries have the ability to deploy nuclear weapons via smaller range missiles at altitudes capable of causing devastating consequences. Both Iran and North Korea have reported tests describing mid-flight detonations of such missiles. Intelligence analysts have stated they believe these tests were designed to exercise HEMP capabilities.

The United States is at significant risk from even moderately sized weapons. A terrorist country or organization might have trouble putting a nuclear warhead “on target” with a Scud, but it could easily launch a missile from a freighter in international waters, and detonate a crude nuclear weapon in the atmosphere high above one of our coastal cities.

In a briefing to the congress, Senator Jon Kyl said, “A single Scud missile, carrying a single nuclear weapon, detonated at the appropriate altitude, would interact with the Earth’s atmosphere, producing an electromagnetic pulse radiating down to the surface at the speed of light. Depending on the location and size of the blast, the effect would be to knock out already stressed power grids and other electrical systems across much or even all of the continental United States, for months if not years.”

In a briefing to the House Armed Services Committee, a congressional commission reported that “HEMP is one of a small number of threats that can hold at risk the continued existence of civil society within the United States, and our ability to maintain national security and project military power anywhere it is needed . . .This threat also places our national economy and worldwide military forces at risk.”

Another scientist said, “An electromagnetic pulse (EMP) attack on the American homeland, is one of only a few ways that the United States could be defeated by its enemies – terrorist or otherwise, and it is probably the easiest.” The report stated, “The loss of power beyond emergency power supplies may well cripple financial systems, telecommunication, health care, emergency response, government control, water and food supplies and other critical societal functions — a potentially escalating rather than diminishing situation”.

The commission said a blackout of the power grid would be “virtually certain” following such an attack. Moreover, the briefing states, the panel predicted a “high proportion of computers” and other systems would be affected; major telecommunications would be interrupted; many high-frequency, VHF and UHF receivers would be damaged; and cell phone, satellite and Internet communications would be hindered.

Other infrastructure impacts could include damage to fuel supply and refineries, the transportation system, water supply and sanitation, chemical plants, financial systems, health care, emergency response and “government integrity.” The loss of power would have a cascading effect on all aspects of U.S. society. Communication would be largely impossible. Lack of refrigeration would leave food rotting in warehouses, exacerbated by a lack of transportation as those vehicles still working simply ran out of gas (which is pumped with electricity).

The inability to sanitize and distribute water would quickly threaten public health, not to mention the safety of anyone in the path of the inevitable fires, which would rage unchecked. And as we have seen in areas of natural and other disasters, such circumstances often result in a fairly rapid breakdown of social order…. Not only would there be nobody nearby to help, it could take years to replace destroyed equipment.”

Information sourced from the non-profit organization, The American Civil Defense Association.


  1. threats against the grid in general

    New ISIS threat: America’s electric grid; blackout could kill 9 of 10


    9 Electric Power Grid Substations Will Bring It All Down


    the sad thing is
    Congress is well aware of the threats to the grid
    and they have done virtually nothing to protect it

    1. Why would you expect any thing else. These are the authors of destruction.

  2. How many nuclear power stations would eventually go out of control, by either control failures or fuel delivery interruptions causing cooling failures?

      1. Yes. That is a fatal flaw built into our dependance on power. Nuclear plants would fail and ,eventually, flood the earth with enough radioactive material to make life unsustainable. Kind of a downer to realize. They didn’t mention that in ‘One second after’ did they……..

        1. That would of made a short story if they put that in….one where everyone dies

  3. A HEMP device needs to be 250 miles above the surface of the earth to affect the entire US, not 25.

    1. NVM, you mentioned 200 miles in the article. Title is misleading at best.

      1. The article says, “Any nuclear detonation above 25 miles will cause a high altitude EMP”. It does not say a 25 mile high detonation will affect the entire US.

        “A nuclear weapon detonated at an altitude of 200 miles could affect all unprotected electrical equipment within the continental United States.” (emphasis on “could”)

        I don’t think anyone is misleading here.

  4. I can’t see a Scud getting the required altitude or any single modern nuke causing EMP across the US. Starfish Prime at 1.4 MT did a lot less. I’m basing the later on distance. Electronics were a lot harder in 1962.

    1. There are four variants of the Scud missile.

      Converted their km range (Wikipedia) to miles:

      Scud-A (112 mile range)
      Scud-B (186 mile range)
      Scud-C (341 mile range)
      Scud-D (621 mile range)

      Not sure how range would relate to achieving altitude, but it does seem plausible if launched regionally (freighter ship?). Anything’s possible I suppose.

  5. You have to consider the likely response too. Whether you detonate it on the ground, or in the air, you just launched a nuke at the United states. Do you really think that there are any lines left that they wont cross when it comes to their response? Did you value, in any way, that country you once came from? Because it wont be there when you try to go back to it. There are a few nuke subs out there that can make sure of that.

    1. … but there’s an idiot in the White House and even after those ‘red lines’ are crossed, he has no plan except another round of golf or a fundraiser to use his podium-voice at.

  6. FYI
    North Korea has launched ICBM’s.
    It’s not new to the world.
    The WW2 V2 rocket was exoatmospheric.

    1. North Korea has not been able to successfully launch a missle with an intercontinental range (an ICBM). The have been able to build and launch short and meduim range balistic missles, but have not had success with longer range, multistage rockets that they attempt to develope.

  7. We simply will not know who attacked us, when the lights go out. We will not know if the lights went out due to a solar event, or as the result of an attack. We will just be in the dark…wondering.

    The military may know the difference between an attack and a solar event, but how will they know who attacked us, if that is the case? The bomb radioactive signature will be unavailable. If the launch vehicle comes from the sea, or the South, we would have no idea from trajectory. Whom do you blame? Do we EMP everyone, and bring every known enemy down? Do we have EMP weapon response planned, or simply mushroom clouds? Is the communications to our SUBS capable of standing up to an EMP? What does a Sub Commander do, when he must act without directed command? Once EMP’ed, why not use a ground burst at Washington DC? An EMP would blind, and a few ground bursts would be a punch to the gut. No launch warning, as the devices used could already be in place at their targets (The trunk of a car, or a nice storage unit.)

    Since, this kind of attack triggers all out response, why would the enemy not maximize it? If China and Russia get an automatic response from us, wouldn’t it mean they both have an interest in preventing such an attack upon us by rouge nations and groups?

    I think the nuke plants are mostly, but not all, EMP proof in regards to being able to SCRAM and cool. But, if 20 plants are good, and 5 are not, we are still pretty much screwed.

    Oh, well. We live until we do not.

    1. Majority of the military’s critical electronics has been hardened to protect against EMP. Most of the major credit card companies have done the same to their computer files so I guess we will all have to pay our bills after the big one. I would like to think we would nuke the hell out of anyone who tries this crap but the POTUS would most likely enjoy the US being reduced to a third world country. Wasn’t there a TV program ten years ago staring Jessica Alba where the US had been hit by EMP’s and reduced to a third world country?

    2. Well, you the individual might not, but there will be people that know what it was. Solar events give a few hours notice(to those that have the right equipment monitoring for it, ie NASA, etc) that something big is coming. Enough time even, if they have the balls to do it, to issue a warning, and perhaps segment the power grid to minimize damage. Political suicide if it ends up not hitting/causing damage though.

      And the military still monitors all ICBM-like launches. Even in the 60’s they were aware of the threat and had plans in place for a sneak nuke attack. They might not put as much likelihood on that scenario any more, but they’re not blind to it all.

  8. I was in the middle writing a comment about how I just went on vacation with my three brothers and how they think I am crazy to prep. I sent all three of them the article about the billionaire Mr. Singer telling his investors to be aware of the potential grid breakdown yesterday, when I received a reply from my one brother today asking about water filters.

    After all these years of preaching I finally might have opened the door a little. My other brother does believe that there is going to be a financial meltdown but other than diversifying his investments he doesn’t see the need to prep. If it does happen there are going to be a lot of ramifications that most people would not believe. Good people will turn real ugly when there’s no food on the table. Well I guess I will just keep plodding along and hope I am ready to take care of my family if the time comes. I still have a long way to go. I would also like to thank all of you for all of the information everyone has so freely shared.

  9. Why does the government have to beef up the power grid? The power grid is owned by private electric companies, they should start spending some of their profits on their respective power lines. Instead of giving it all to the share holders/directors. When a natural disaster happens why doesn’t the electric co. upgrade their infrastructure(s) then. Then they wouldn’t have to spend a lot of money at once but, gradually over time.

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