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Dept. of Homeland Security Warns of Threats From Manmade EMP Attacks

DHS Urges Public and Private Critical Infrastructure to Harden Facilities

The U.S. Department of Homeland Security (DHS) has issued a new report warning of the threat of manmade electromagnetic pulse (EMP) attacks and urges critical infrastructure (CI) sectors to harden facilities.

An EMP is a quick, powerful blast of electromagnetic energy that can destroy electronics while leaving all other physical structures intact. EMPs may occur naturally (lightning, solar flares) or may happen artificially (nuclear detonation).

The DHS report on securing CI was released by the DHS Science and Technology Directorate, which develops guidance on EMP mitigation investments for both public and private sectors.


Public awareness of the potential for manmade EMPs began in 1962 after the U.S. government detonated a thermonuclear weapon 250 miles above an island in the Pacific Ocean. After detonation, 900 miles away in Hawaii, 300 streetlights shut off nearly simultaneously, burglar alarms were triggered, and circuit breakers opened.

Several months later, the Soviet Union conducted high-altitude tests over part of Sibera, which DHS says inadvertently demonstrated “the weaponization potential of high-altitude EMP.”

A successful EMP attack on the U.S. could lead to a nationwide blackout of the electric power grid, along with a shutdown of all CI reliant on the grid, according to Stanford University. Industries that would be affected include communications, transportation, food and water supply, and sanitation.

A power grid shutdown after an EMP attack could last up to a year, which a congressional EMP commission estimated could lead to 90 percent of the U.S. population dying from starvation, disease, and societal breakdown. Stanford says that “in a worst-case scenario, all nuclear reactors in the affected region could be impacted, leading to as many as 60 meltdowns similar to Japan’s Fukushima Daichi Nuclear Disaster.”

Protecting U.S. Infrastructure

The DHS report states:

EM signals such as those generated by EMP can couple to equipment circuits through chassis apertures (e.g., slots, holes, windows), communications networks, and power conductors.

Electric fields levels can be reduced through EM reduction techniques such as housing MCE in shielded cabinets and enclosures, and the use of filters, fiber optic cables (as opposed to coaxial cables), and non-linear protection devices that provide surge protection. Points of entry (POE), or penetrations that could allow [electromagnetic] energy into the shielded enclosure, should be protected by a POE protective device.

DHS recommends that mission critical electronics (MCE) be placed into EMP-protected shelters, with EMP filters on lines going through the shelter’s points of entry and EMP-rates surge protectors on power lines leading to critical equipment.

“The use of shelters to group equipment reduces the number of components and devices that must be verified and maintained throughout the life of the system,” the report states.

The agency also recommends placing external communications and power lines underground and that portable equipment be secured in an EMP-shielded cabinet or faraday cage.

“As the entire system may not be shielded, the solution may rely on the availability of working spare parts and the execution of operational procedures to bring the system back online after an EMP event,” the report says.

Federal officials are also urging routine inspections of EMP shielding, a maintenance plan, and periodic training for personnel associated with CI operation and maintenance.

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