Medary.com

U.S. Satellite Protection Scheme Could Affect Global Communications

The remediation system aims to protect hundreds of low earth-orbiting satellites from having their onboard electronics ruined by charged particles in unusually intense Van Allen radiation belts "pumped up" by high-altitude nuclear explosions or powerful solar storms.

The approach, which is being pursued by the US Air Force and the US Defense Advanced Research Projects Agency, involves the generation of very low frequency radio waves to flush particles from the radiation belts and dump them into the upper atmosphere over one or several days.
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Dr Mark Clilverd from British Antarctic Survey says, "Some planes and ships that rely on HF communications could lose radio contact, and some remote communities that also depend on HF could be isolated for as long as six to seven days, depending on the system's design and how it was operated. GPS signals between ground users and satellites would also be disrupted as they pass through the disturbed ionosphere."

The article implies that this system would, in part, suppress the effects of an electromagnetic pulse attack.  Wild, weird, amazing stuff, if it works.