EMP Effects of a Nuclear Weapon

According to the executive director of the Task Force on National and Homeland Security, North Korea has the capacity at this time to deliver a nuclear weapon via ICBM (intercontinental ballistic missile) to the United States. Obviously the U.S. could respond with thousands of weapons that would obliterate that country, but that would not undo the colossal damage of a single nuclear weapon exploded at high altitude above the United States.
As far back as 2004, the Russians notified the Congressional Electromagnetic Pulse Commission that North Korea had acquired the information necessary for construction of a super-EMP warhead. Such a nuclear weapon would release gamma rays that would strip electrons from atoms in the upper atmosphere, creating an electromagnetic pulse that would destroy our electric power grid.
An explosion at a height of 200 miles could knock out much of the electronics across the US making a reality of the current TV series “Revolution” in which people have to adjust to life without electricity with the inherent loss of communications, lighting, computing, and transportation systems. The economy would collapse; and according to the Congressional EMP Commission, two-thirds of the U.S. population could die within the first year as a result of starvation, disease, and the turmoil resulting from the collapse of the infrastructure of the nation.