An EMP is a burst of electromagnetic radiation typically generated by a high-altitude nuclear explosion or a non-nuclear device. Nuclear weapon EMPs are most effective when detonated high in the altitude above the intended target.
Depending on the yield of the weapon and the height of the explosion, nuclear EMPs can destroy large portions of the U.S. power and communications infrastructure.
Geomagnetic radiation generated by a naturally occurring solar storm can also damage this same infrastructure. An EMP attack would destroy the electronics and digital circuitry in the area of impact, denying electric power to our homes, businesses, and military.
Our country is dependent on electricity to power our health, financial, transportation, and business systems. If our power system was ever lost for an extended period, according to Dr. William Graham the chairman of the EMP Commission, it would have catastrophic and lethal consequences for our citizens and the economy. It would also degrade our military defenses. America's digital dependence grows every year and along with that dependence, our EMP vulnerability.