Increasing aggressive North Korean rhetoric has prompted the Pentagon to decide to deploy a high-profile missile-defense system on the island of Guam. The Defense Department announced Wednesday that it would soon move the Terminal High Altitude Area Defense System (THAAD) to the island. 

This comes in addition to deployment of two destroyers equipped with Aegis missile defense systems, the Decatur and the John McCain, to the region – a reversal by the Obama White House of previous Bush administration plans. On Wednesday, Defense Secretary Chuck Hagel stated bluntly that North Korea’s most recent threats “present a real and clear danger.”

One of those “dangers” – probably the greatest, in fact – is that tested in December 2012, the three-stage missile sent into orbit by Pyongyang in defiance of international mandates. Experts believe the satellite launch might have been a test to orbit a nuclear payload that could then be de-orbited upon command and exploded at high altitude, releasing an electromagnetic pulse (EMP).

A little-known 2011 study by the U.S. Army War College entitled “In the Dark: Military Planning for a Catastrophic Critical Infrastructure Event” predicted the possibility more than a year ago. It also warned a nuclear detonation at altitude above a U.S. city could wipe out the electrical grid, possibly in a radius of thousands of miles.

An article posted last week on the website, noted the December test coincided with a “nuclear test of a higher level,” that may have referred to a device made from highly enriched uranium. This substance is easier to miniaturize into an EMP device than the plutonium bombs tested by North Korea in 2006 and 2009, according to South Korean analyst Cheong Seong-chang, an employee of the Sejong Institute. 

Such an EMP device, he said, would have a low yield and would not be designed to create a big explosion. Rather, it would convert its energy into gamma rays to generate the electromagnetic pulse that could knock out the nation’s infrastructure.

The explosion over the United States – or anywhere else -- would instantly destroy the nation’s power grid and all electronic circuitry. 

Israel destroyed a nuclear plant that was under construction in Syria with the clear assistance of North Korea on September 6, 2007.