Many consider an electromagnetic pulse (EMP) attack on the United States, from an atmospheric nuclear warhead detonation, to be a black swan event – a high-impact, unpredictable event. But we have known about the threat of an EMP attack since early atmospheric testing in the early 1960s. Furthermore, it seems even more reasonable today that our adversaries may choose to cripple the U.S. in a fatal first punch rather than engage the U.S. in a war of attrition. EMP is a line-of-sight phenomenon associated with the detonation of a nuclear warhead and the pulse it emanates can bridge the integrated circuitry of electronic components, especially those connected to long lead conductors like antennas, transmission lines, or internal building wiring, or something as simple as the electrical cord on an appliance plugged into the wall. The bridging, or electrical arcing across integrated circuity, can disrupt the usage of the electronic component requiring it to be cycled or restarted, or the bridging can burn out the circuitry or chip thus destroying the function of the electronic component.
The fact that EMP effects can cause extensive damage and destruction to critical infrastructure over large areas is well understood and an asymmetric means an adversary can employ to cause nationwide damage. We have known the effects of EMP on critical infrastructure for over 60 years. The EMP threat to the U.S. is less a black swan event and more like an ostrich event, where the U.S. knows about the threat and the rising risk but has its proverbial head in the sand out of fear instead of taking useful action.
The U.S., like many modern societies, has become increasingly reliant on highly interdependent infrastructure sectors that use electronic components with integrated circuitry. Just think how pervasive electronic devices have become within our everyday lives: trucks, cars, trains, planes, smartphones, radio, television, satellites, landlines, heating, air conditioning, refrigeration, freezers, television, and medical equipment. And it’s becoming even more worrisome as modern societies will be turning toward artificial intelligence and machine learning algorithms to solve growing complex societal problems and aid human decision making. Our dependence on electronics and its integrated circuitry has made the U.S. highly vulnerable to the EMP effects of a nuclear detonation. This may be why our adversaries, especially those unable to project conventional warfighting, may turn toward EMP effects of a nuclear warhead to deliver a fatal punch to the U.S.
The Mechanics of EMP
The largest EMP threat to critical infrastructure of a modern society is generated by a nuclear warhead denotation in the mid- to upper-stratosphere or approximately 20-30 miles above the earth’s surface, which is referred to as a High-Altitude EMP (HEMP).[i] A HEMP occurs when a nuclear detonation generates an intense burst of gamma radiation which radiates outwards from the nuclear detonation source. The gamma rays that radiate downward toward the earth’s surface will eventually encounter a point where the atmospheric density rapidly increases, and the gamma rays will begin to interact with air molecules.[ii] This is known as the deposition region, and it is here that the gamma rays produce Compton electrons and positive ions that continue to radiate away from the nuclear detonation source. These electrons radiate at a much higher velocity than the positive ions due to their lower mass and this charge displacement results in a current flow toward the deposition region followed by a current flow away from the deposition region as the charged particles begin to recombine.[iii] It is this phenomenon that generates the EMP effects, which can produce an average pulse of up to 50,000 volts/meter.[iv] The Compton electrons generated by gamma radiation in the deposition region are deflected by the earth’s magnetic field and therefore the area of maximum effect on the earth’s surface is highly dependent upon weapon yield, orientation, and at what latitude above the earth the weapon is detonated.[v]
HEMP effects from a nuclear detonation have little impact to humans on the Earth’s surface, however, that is contrasted by a near surface detonation of a nuclear weapon whose primary damage mechanism is air blast, thermal radiation, ionizing radiation, and radioactive fallout that can have devastating effects on humans near and far away from the ground burst. The EMP generated by a nuclear weapon ground burst is generally of little significance because the charged particles can quickly recombine through the ground, which is a good electrical conductor. In addition, the gamma rays radiating upwards will not affect infrastructure on the ground, which will be vaporized or burned by thermal radiation. Therefore, the area affected by the EMP generally will not radiate past the moderate damage zone where most infrastructure is destroyed by air blast and thermal radiation anyway, resulting in a building blow down effect and ignited firestorms, respectively.[vi] The exception to this is if a ground burst and its EMP is transmitted along an existing electrical conductor near ground zero, which can damage infrastructure outside the moderate damage zone. Basically, EMP is a line-of-sight phenomenon, limited by the Earth’s curvature and ground topography. However, the higher in the atmosphere a nuclear weapon is detonated the greater the reach of regional or nationwide EMP effects on electronic components.
Likely Effects from an Electromagnetic Pulse Attack
EMP damage to the energy infrastructure sector, specifically the electrical grid, would have the greatest negative impact to our modern society because all other critical infrastructure sectors are dependent on electricity. Areas within our society most dependent on electricity include telecommunication, banking and finance, petroleum and natural gas, transportation, water, emergency services, space control, and continuity of government.[vii] Some of these key areas have backup electrical generation in the form of gas or diesel generators or batteries, but these are just temporary bridges until electricity is more widely restored. In the event of an EMP, the integrated circuitry of electronic components within the electrical grid will be damaged or destroyed causing cascading and escalating impacts to almost all other 15 infrastructure sectors.[viii] Our modern society, like many others, will break down very quickly within hours, days, and weeks.
The electrical grid is composed of power generation (coal-fired, natural gas, nuclear, etc.), transmission, and distribution infrastructure.[ix] The current and voltage induced on an electrical system by an EMP are directly proportional to the length of the electrical conductors connected to it.[x] As such, the large outdoor transmission towers and lines we try to ignore on our landscape could be our undoing as they are highly efficient at capturing EMP energy and transmitting it to its endpoints, which includes high-voltage transformers (HVTs). HVTs are often near power-generation plants and their role is to step up the voltage of the generated power at the expense of the current. Electrical power (measured in Watts) is defined as the product (multiplication) of voltage (measured in Volts) and current (measures in Amperes). As such, electrical power is most efficiently transmitted with lower loses by greatly increasing voltage through an HVT at the expense of current, because the amplification of current causes transmission lines to overheat which is directly correlated to much lower transmission efficiency. HVTs are massive and custom-designed machines built by hand thus requiring extensive labor. Consequently, the building of HVTs is often offshored to different vendors meaning the U.S. has a limited organic manufacturing capability.[xi] The obvious result is that if a large percentage of HVTs in the U.S. were destroyed by a HEMP, it would take months to years to replace them due to their custom designs, long-lead acquisition times, permitting, logistical, and transportation limitations. One argument is that the U.S. could develop that manufacturing capability to respond to a crisis, but the reality is that the response would be hampered by resource loses across almost every infrastructure sector and would be tantamount to changing a car tire while the car is engulfed in flames. In addition, a HEMP generated by a nuclear explosion at the right altitude could potentially damage a huge number of electrical components with integrated circuitry within line-of-site of the nuclear explosion. In fact, an estimated 70 percent of the electrical grid could be damaged from the HEMP of just one nuclear weapon.[xii]
A HEMP attack over the continental U.S. would be catastrophic because most Americans today live in a modern first-world society and do not possess the survival skills necessary to live in a world without electricity. The reality is the U.S. would likely collapse within weeks or months due to lack of potable water, disease, starvation, social unrest, violence, etc. Undoubtedly, the U.S. would immediately retaliate if it could attribute the EMP attack to a nation-state; regardless, the damage to the U.S. would be done, and the U.S. federal government would be completely overwhelmed with responding to an escalating domestic crisis and focused on the population’s basic survival needs rather than executing foreign policy.
In addition to the U.S. electrical infrastructure being a huge EMP concern, the U.S. telecommunications infrastructure is also vulnerable to HEMP. Telecommunications infrastructure includes telephone and wireless cell service, broadband internet and associated servers and routers, cable television, satellite communications ground stations, and all equipment associated with sending or receiving voice, data, or video messages.[xiii] Our ability to communicate during any kind of national emergency is vital; however, the telecommunications infrastructure is dependent upon the electrical infrastructure, so even if the communications systems themselves survived the EMP event there would be little functionality beyond the duration of the generator and battery backup systems. Furthermore, many Supervisory Control and Data Acquisition (SCADA) systems, vital in many critical infrastructure sectors, are dependent on the communications infrastructure – and when communications fail, the SCADA systems and its operators would be blinded.[xiv]
Some work has been done to protect aspects of U.S. critical infrastructure sectors through EMP simulators to test equipment, which revealed that not every component would be destroyed but that some would only require power cycling to start functioning normally again.[xv] However, looking at the high interdependencies of our electrical grid by all of the other 15 infrastructure sectors, if a large enough percentage of infrastructure sectors were damaged then our recovery from a broad EMP attack would take years if not decades. The result of a HEMP attack would be an inability to provide basic needs to the population such as potable water, non-perishable food, heating/cooling, and healthcare, which in turn would undoubtedly lead to violence over diminishing resources and eventual societal collapse.
Adversary EMP Capabilities
A HEMP attack on the U.S. is well within the capabilities of North Korea and other countries such as China and Russia. Multiple credible sources from South Korea, China, and Russia have stated that Russian designs for an enhanced EMP, or “Super EMP,” weapon have been leaked or acquired by North Korea.[xvi] Super EMP weapons are designed to produce more intense gamma radiation at the expense of a smaller nuclear explosion in order to enhance the HEMP effects generated in excess of 100,000 volts/meter, twice the standard of what U.S. military systems are designed to withstand.[xvii]
An existing North Korean EMP threat may already be on orbit above the U.S. KMS-3 and KMS-4 are North American Aerospace Defense Command’s designated acronyms for North Korea’s Kwangmyongsong-3 and Kwangmyongsong-4 satellites that were launched into orbit in 2013 and 2016, respectively. Based on the polar orbits and revisit time over the U.S., they could possibly have a sinister capability like a Super-EMP weapon. In addition, North Korea also possesses two Intercontinental Ballistic Missile (ICBM) systems with sufficient payload capacity and range to deliver an EMP weapon in space over the continental U.S: the Hwasong-14 with a range of 10,000 km (6,200-plus miles) and the Hwasong-15 with a range of 13,000 km (8,000-plus miles).[xviii] Although these missile systems have not yet demonstrated the systems integration for warhead reentry and the accuracy required for precision strike on a U.S. city, they are more than accurate enough to deliver and detonate a nuclear warhead in space above the continental U.S. and the HEMP would be devastating. The fact that North Korea has not pursued integration testing and accuracy testing needed to destroy a U.S. city by a nuclear warhead is perhaps even more troubling as it may be an indication of a HEMP attack strategy versus a city destruction strategy. Future North Korea ICBM missile development programs will undoubtedly have greater range and payload capacity. Interestingly, a retaliatory U.S. attack on North Korea with a HEMP attack would have little effect since the country is highly agriculturally based and has a limited electrical grid. It has been traditionally viewed that North Korea would be unlikely to conduct such a HEMP attack unless under dire circumstances based on the influence of Russia and China; however, just recently North Korea has eliminated controls to allow it to lawfully use a nuclear attack as a preemptive strike.[xix]
A HEMP attack against the U.S. would cause cascading and escalating failures across multiple infrastructure sectors and would be far more devastating due to the high likelihood of societal collapse over a larger region than a nuclear ground detonation against a U.S. city or point-target. As such, U.S. national leadership should make it abundantly clear to our adversaries that any attempt to degrade or destroy U.S. critical infrastructure with a HEMP attack warrants a U.S. nuclear response. This type of deterrence is paramount to countering the emerging threat of Super EMP weapons that North Korea may be viewing as an advantageous asymmetric capability. An important part of this deterrence is demonstrating national resiliency. The key to minimizing the effects of HEMP is to institute systems that will minimize recovery times because replacing countless electronic components with more EMP-resistant ones in the U.S. electrical infrastructure sector is impractical.[xx] Consequently, enhancing the resiliency and recovery capacity of our critical infrastructure, but also demonstrating the government’s ability to provide a robust domestic response and recovery capability, would help serve as a HEMP attack deterrent on the U.S. The framework to take these actions already exists with the National Response Framework (NRF), National Incident Management System (NIMS), and Incident Command System (ICS) adopted nationwide in the wake of the September 11 attacks on the World Trade Center.[xxi] U.S. Northern Command (USNORTHCOM) manages the CBRN Response Element (CRE), which is designed to provide Defense Support to Civil Authorities (DSCA) for Chemical Biological Radiological and Nuclear (CBRN) events. This domestic response capability is robust and could easily serve as the framework for an EMP response capability. The fact that the various military units assigned to the CRE are dispersed among 35 separate military installations ensures that large portions of the enterprise are still able to respond.
Most modern electronic devices today with integrated circuitry have some degree of shielding built in, but this shielding is intended to reduce or eliminate electromagnetic interference from other electronic devices. This existing shielding is not rated to withstand an EMP. Note that an EMP reaches a peak strength many magnitudes of times faster than a lightning strike, which in turn would defeat all common shielding or surge protection available to the general population.[xxii] The federal government should either mandate or incentivize the development of more resilient electronic components to handle this type of EMP energy within telecommunications, banking and finance, petroleum and natural gas, transportation, water, emergency services, space control, and continuity of government areas.[xxiii] This could be done by providing manufacturers additional tax exemptions if their systems meet a minimum specification of shielding to reduce the likelihood of total failure, which is possible depending on the distance from the EMP deposition region. For example, electrical components within line of sight of a nuclear-generated HEMP, but further away from the area primarily affected, will experience much weaker EMP than those areas directly underneath the deposition region and therefore could possibly still function if shielding is increased.[xxiv] Additionally, telecommunications companies can continue to replace long runs of copper wire used for broadband internet service with fiber-optic lines, which are highly resistant to the effects of EMP.[xxv] Moreover, removal of long runs of wire will likely result in reduced coupling of EMP effects on the entire system.
The key to any kind of disaster recovery is communication. As such, the U.S. government should consider continuing its funding of the Military Auxiliary Radio System (MARS) and the Department of Homeland Security (DHS) SHAred RESources (SHARES) High Frequency (HF) radio program. MARS is a Department of Defense (DOD) sponsored program that was started in 1925 and continues today with the mission of providing local, national, and international contingency communications capability using High Frequency (HF) radio.[xxvi] SHARES HF administered by the Department of Homeland Security’s (DHS) National Coordinating Center for Communications (NCC), provides an additional means for national security and emergency preparedness (NS/EP) personnel to communicate critical information when other telecommunications infrastructure is inoperable.[xxvii]
North Korean military leadership probably knows that it will likely never achieve economic, defense, or nuclear parity with the U.S., but they likely see the possession of a HEMP and Super EMP weapons as an asymmetric alternative to an arms race they will never win. A HEMP or Super EMP weapon detonated above the U.S. can inflict an incredible amount of damage on U.S. critical infrastructure which the U.S. may not recover from based on the lack of current investment to harden our most critical infrastructure. U.S. policy makers must go beyond studying the HEMP threat and fund tangible hardening of electronic components across our infrastructure sectors starting with our electrical grid to increase our resiliency and reduce our recovery time if attacked. Such an investment would not only deter attacks of this nature but also protect the electrical grid from other known threats such as a coronal mass ejection from the sun within our solar system that aligned with the Earth’s orbit.
The authors are responsible for the content of this article. Their views expressed do not reflect the official policy or position of the National Intelligence University, the Office of the Director of National Intelligence, the U.S. Intelligence Community, U.S. Department of Defense, or the U.S. Government.
Cybersecurity and Infrastructure Security Agency (CISA), “SHARES Program Information.” Accessed November 11, 2022. https://www.cisa.gov/shares-program-information
Defense Threat Reduction Agency (DTRA). Electromagnetic Pulse (EMP) Discussion. November 2017.
Department of Defense (DOD) and Department of Energy (DOE). The Effects of Nuclear Weapons Third Edition, by Samuel Glasstone and Philip J. Dolan. 1979.
Department of Defense (DOD) Instruction 4650.02, Military Auxiliary Radio Station. December 20, 2021. Accessed May 8, 2023. DoDI 4650.02, “Military Auxiliary Radio System,” December 20, 2021 (whs.mil)
Department of Homeland Security (DHS). Strategy for Protecting and Preparing the Homeland Against Threats of Electromagnetic Pulse and Geomagnetic Disturbances, October 2018.
Department of Transportation (DOT), Federal Aviation Administration. Electromagnetic Pulse (EMP) Protection Study: A Reexamination and Update, by Chin-Lin Chen and Warren D. Peele. November 1979.
EMP Task Force on National and Homeland Security. North Korea: EMP Threat; North Korea’s Capabilities for Electromagnetic Pulse (EMP) Attack, by Dr. Peter Vincent Pry. June 2021.
US Congress, House. Report of the Commission to Assess the Threat to the U.S. from Electromagnetic Pulse (EMP) Attack; Volume 1: Executive Report. 2004. http://www.empcommission.org/
US Congress, House. Report of the Commission to Assess the Threat to the U.S. from Electromagnetic Pulse (EMP) Attack. April 2008. http://www.empcommission.org/
[i] US Congress, House. Written Testimony of Dr. Randy Horton for the Hearing of the U.S. Senate Homeland Security and Governmental Affairs Committee. Perspectives on Protecting the Electric Grid from an Electromagnetic Pulse of Geomagnetic Disturbance. February 27, 2019. Testimony-Horton-2019-02-27.pdf (senate.gov)
[ii] Department of Defense (DOD) and Department of Energy (DOE). The Effects of Nuclear Weapons Third Edition, by Samuel Glasstone and Philip J. Dolan. 1979, 518.
[iii] Department of Transportation (DOT), Federal Aviation Administration. Electromagnetic Pulse (EMP) Protection Study: A Reexamination and Update, by Chin-Lin Chen and Warren D. Peele. November 1979, 8.
[iv] Department of Transportation (DOT), Federal Aviation Administration. Electromagnetic Pulse (EMP) Protection Study: A Reexamination and Update, by Chin-Lin Chen and Warren D. Peele. November 1979, 3.
[v] Department of Defense (DOD) and Department of Energy (DOE). The Effects of Nuclear Weapons Third Edition, by Samuel Glasstone and Philip J. Dolan. 1979, 519.
[vi] Department of Defense (DOD) and Department of Energy (DOE). The Effects of Nuclear Weapons Third Edition, by Samuel Glasstone and Philip J. Dolan. 1979, 517.
[viii] The U.S. has 16 critical infrastructure sectors that include Chemical; Commercial Facilities; Communications; Critical Manufacturing; Dams; Defense Industrial Base; Emergency Services; Energy; Financial Services; Food and Agriculture; Government Facilities; Healthcare and Public Health; Information Technology; Nuclear Reactors, Materials, and Waste; Transportation Systems; and Water and Wastewater Systems.
[x] Department of Transportation (DOT), Federal Aviation Administration. Electromagnetic Pulse (EMP) Protection Study: A Reexamination and Update, by Chin-Lin Chen and Warren D. Peele. November 1979, 18.
[xvi] EMP Task Force on National and Homeland Security. North Korea: EMP Threat; North Korea’s Capabilities for Electromagnetic Pulse (EMP) Attack, by Dr. Peter Vincent Pry. June 2021, 2.
[xvii] Defense Threat Reduction Agency (DTRA). Electromagnetic Pulse (EMP) Discussion. November 2017, 8.
[xviii] EMP Task Force on National and Homeland Security. North Korea: EMP Threat; North Korea’s Capabilities for Electromagnetic Pulse (EMP) Attack, by Dr. Peter Vincent Pry. June 2021, 10.
[xix] Josh Smith, Reuters, New North Korea law outlines nuclear arms use, including preemptive strikes. As accessed on November 14, 2022 at https://www.reuters.com/world/asia-pacific/un-chief-guterres-deeply-concerned-by-new-north-korea-law-nuclear-weapons-2022-09-09/
[xx] US Congress, House. Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack; Volume 1: Executive Report. 2004, 20. http://www.empcommission.org/
[xxi] Department of Homeland Security (DHS). Strategy for Protecting and Preparing the Homeland Against Threats of Electromagnetic Pulse and Geomagnetic Disturbances, October 2018, 16.
[xxii] Department of Transportation (DOT), Federal Aviation Administration. Electromagnetic Pulse (EMP) Protection Study: A Reexamination and Update, by Chin-Lin Chen and Warren D. Peele. November 1979, 17.
[xxiv] Department of Defense (DOD) and Department of Energy (DOE). The Effects of Nuclear Weapons Third Edition, by Samuel Glasstone and Philip J. Dolan. 1979, 536.
[xxvi] DOD Instruction 4650.02, Military Auxiliary Radio System. December 20, 2021. Accessed May 8, 2023. DoDI 4650.02, “Military Auxiliary Radio System,” December 20, 2021 (whs.mil)