Electromagnetic Pulse or an EMP are oversized outbursts of atmospheric electricity. Whether powered by geomagnetic storms or by nuclear blasts, their resultant intense magnetic fields can induce ground currents strong enough to burn out power lines and electrical equipment across state lines, says USA Today.

At risk are the more than 200,000 miles of high-voltage transmission lines that cross North America, supplying 1,800 utilities the power for TVs, lights, refrigerators and air conditioners in homes, and for the businesses, hospitals and police stations.

"Natural EMP from a geomagnetic superstorm, like the 1859 Carrington Event or 1921 Railroad Storm, and nuclear EMP attack from terrorists or rogue states, as practiced by North Korea during the nuclear crisis of 2013, are both existential threats that could kill 9-of-10 Americans through starvation, disease and societal collapse," the Washington Free Beacon quoted Pry as saying.

Pry, a former CIA nuclear weapons analyst, believes that North Korea's recent seemingly low-yield nuclear tests and launch of a low-orbit satellite may be preparations for a future electromagnetic pulse attack.

As the Heritage Foundation has reported, an EMP attack with a warhead detonated 25 to 300 miles above the U.S. mainland "would fundamentally change the world: "Airplanes would fall from the sky; most cars would be inoperable; electrical devices would fail. Water, sewer and electrical networks would fail simultaneously. Systems of banking, energy, transportation, food production and delivery, water, emergency services and even cyberspace would collapse."

Read more: http://usatoday30.usatoday.com/tech/science/2010-10-26-emp_N.htm