emp. mark: welcome back, dr. peter pry. what would be, before we get to the question of how do we protect ourselves? the question is, we need to figure out how we might be attacked? what are the different scenarios, i'm sure there are many, which a country might want to shut down our electrical grid? >> north korea could shut down our grid by an emp attack off a satellite. they in fact have two satellites orbiting over this country as we speak that pass over us several times a day, at optimal altitude to evade our national defense systems. mark: how would they make an emp field? >> detonate the satellite when it's over the center of the country and the field would propagate from the location of the warhead to the line of sight. mark: it would have to be a satellite with a warhead. >> have to be a satellite with a warhead.