America

By John R. Moore June 6, 2017

In April, PJ Media warned of an imminent threat to the U.S. from North Korea – an electromagnetic pulse (EMP) attack from an orbiting satellite. We reported that North Korea already has two satellites orbiting the U.S. and that a nuclear weapon detonated over the U.S. from one could devastate our country, resulting in the deaths of tens of millions from the loss of critical infrastructure.

Shortly after our warning, the respected North Korea analysis site 38North  published an article titled “A North Korean Nuclear EMP Attack? … Unlikely.”  The author, relying on an incomplete and dated report, thought that North Korea would need a hydrogen bomb (thermonuclear weapon) in order to be a threat.

Now, 38North has a new piece on the topic -- “North Korea Nuclear EMP Attack: An Existential Threat.” The author is the former head of the congressional EMP Commission and is a foremost expert on EMP. This article adds to the PJ Media report by confirming that the yield of nuclear weapons already tested by North Korea is sufficient to be devastating. It refutes the prior article:

Thus, even if North Korea only has primitive, low-yield nuclear weapons, and if other states or terrorists acquire one or a few such weapons as well as the capability to detonate them at an altitude of 30 kilometers or higher over the United States. … the EMP Commission warned over a decade ago in its 2004 Report, “the damage level could be sufficient to be catastrophic to the Nation, and our current vulnerability invites attack."

Nuclear EMP from a high-altitude detonation – H-EMP E-1 pulse – is caused when a massive flux of gamma rays strikes the upper levels of the atmosphere. These strip off and accelerate electrons, creating a sudden powerful electromagnetic pulse, which travels to the surface and destroys electronics and can damage power transmission equipment. The result would be a months-long loss of the electrical grid, transportation, computers and communication systems, causing a rapid breakdown of our transportation, food, water and healthcare delivery systems.

The dispute over weapon yield is a result of misinterpretation of the 1962 Starfish Prime H-EMP test, where a powerful 1.4 megaton weapon was detonated over Johnston Atoll. The resulting EMP damaged several systems 800 miles away in Hawaii, including street lights and radios.

This led many to incorrectly assume that such a powerful weapon was necessary for damaging EMP, while North Korea has only tested a .02 megaton weapon. However,  the Starfish Prime weapon design captured most of the gamma flux in the weapon itself, preventing it from reaching the atmosphere. Also, the small fission primary may have produced all of the effective E-1 pulse, as it ionized the atmosphere, preventing the pulse from the subsequent, huge secondary from having a significant effect. This means that a much smaller gamma flux was sufficient to cause the effect, so small fission weapons, already possessed by North Korea, are enough to cause widespread EMP. Even worse, the gamma flux can be optimized by proper weapon design: