Electromagnetic Pulse and Geomagnetic Disturbance

Stock image of an eletricity bolt over a blue background.Extreme electromagnetic incidents caused by an intentional electromagnetic pulse (EMP) attack or a naturally occurring geomagnetic disturbance (GMD), caused by severe space weather, could damage significant portions of the Nation’s critical infrastructure, including the electrical grid, communications equipment, water and wastewater systems, and transportation modes. The impacts are likely to cascade, initially compromising one or more critical infrastructure sectors, spilling over into additional sectors, and expanding beyond the initial geographic regions adversely impacting millions of households and businesses.

For these reasons, the potential severity of both the direct and indirect impacts of an EMP or GMD incident compels our national attention.

EMP/GMD Overview

EMPs are associated with intentional attacks using high-altitude nuclear detonations, specialized conventional munitions, or non-nuclear directed energy devices. Effects vary in scale from highly local to regional to continental, depending upon the specific characteristics of the weapon and the method of attack. High-altitude electromagnetic pulse attacks (HEMP) using nuclear weapons are of most concern because they may permanently damage or disable large sections of the national electric grid and other critical infrastructure control systems.

Similarly, extreme GMD events associated with solar coronal mass ejections (when plasma from the sun, with its embedded magnetic field, arrives at Earth) may cause widespread and long-lasting damage to electric power systems, satellites, electronic navigation systems, and undersea cables. Essentially, any electronics system that is not protected against extreme EMP or GMD events may be subject to either the direct “shock” of the blast itself or to the damage that is inflicted on the systems and controls upon which they are dependent.


Extreme EMP and GMD incidents fit into the categorization of “hard problems”—both are low probability/high consequence scenarios that challenge effective policymaking. A major electromagnetic incident caused by either EMP or GMD would pose immediate and simultaneous challenges to national and local decision-makers, Sector-Specific Agencies, private sector critical infrastructure owner-operators, and emergency managers at all levels of government.

HEMP attacks by an adversary with basic nuclear weapons and missile capabilities may be disruptive on a regional scale, but are unlikely to cause catastrophic damage to the U.S. electric grid on a continental scale. Adversaries with highly developed nuclear capabilities might cause widespread harm to U.S. infrastructure with complex HEMP attacks in the context of an escalating international conflict.

Space weather phenomena are relatively well understood within the scientific community, but the historical rarity of extreme GMD events limits availability of data useful for predictive analysis. Past events, such as the 1989 solar storm that led to the interruption of power in much of Québec for nearly nine hours, offer proof of the disruptive potential of GMD, as well as their potential to cascade impacts across critical infrastructure sectors and geographic regions.

Executive Order 13865

On March 26, 2019, the Executive Order (E.O.) 13865 on Coordinating National Resilience to Electromagnetic Pulses was signed. The E.O. charges the Department of Homeland Security (DHS) with coordinating national resilience, preparedness, and response from an EMP and GMD event.

The tenants of E.O. 13865 are codified in Section 1740 of National Defense Authorization Act for Fiscal Year 2020 and align to several of the requirements of E.O. 13744: Coordinating Efforts to Prepare the Nation for Space Weather Events—both of which requires DHS along with other federal agencies to coordinate response and recovery efforts to mitigate the effects of EMPs and GMDs, including extreme space weather events, on critical infrastructure.

CISA is leading the Department’s effort by working with the DHS Science and Technology Directorate (S&T), Department of Energy (DOE), Department of Defense (DoD), Federal Emergency Management Agency (FEMA), and state and local utility owners/operators to concurrently understand EMP/GMD effects and footprint, and coordinate solutions to reduce risk.

Building Long-term Resiliency

CISA, through the National Risk Management Center (NRMC), works with government and industry partners to execute the Department’s EMP/GMD Strategy. The Strategy’s three goals are:

  • Improve Risk Awareness of Electromagnetic Threats and Hazards;
  • Enhance Capabilities to Protect Critical Infrastructure;
  • Promote Effective Electromagnetic-Incident Response and Recovery Efforts.

Major ongoing initiatives include partnering with public and private sector entities through the San Antonio Electromagnetic Defense Initiative, partnering with the DOE and the Nuclear Regulatory Commission to ensure the safety of nuclear power plants, and identifying EMP protection/mitigation technologies to set the conditions for future testing.

EMP/GMD Resources

Additional Resources

For questions or comments regarding DHS EMP efforts, email NRMC@hq.dhs.gov.

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