"A nuclear weapon explodes high above the US, unleashing a deadly electromagnetic pulse (EMP) that almost instantly knocks out much of our electrical grid. The electronic control systems in our water, oil, and gas distribution systems fail, and other infrastructure such as telecommunications and transport grind to a halt. While it would be far too high up in the atmosphere (40–400 kilometers) to directly kill people by blast and heat, such an attack would have “the capability to produce significant damage to critical infrastructures and thus to the very fabric of US society”, according to the congressional “Commission to Assess the Threat to US from EMP Attack  (Avail in our Prep Library)

But how likely is this scenario and what should we do about it?

The EMP threat: fact, fiction, and response