A single nuclear weapon exploded at high altitude above the United States will interact with the Earth’s atmosphere, ionosphere, and magnetic field to produce an electromagnetic pulse (EMP) radiating down to the Earth, creating electrical currents in the Earth. EMP effects are both direct and indirect. The former are due to electromagnetic “shocking” of electronics and stressing of electrical systems, and the latter arise from the damage that “shocked”—upset, damaged, and destroyed—electronics controls and then inflict on the systems in which they are embedded. The indirect effects can be even more severe than the direct effects.