Angst over a potential electromagnetic pulse attack bubbles up every few months, and it’s easy to understand why. The EMP impact envisioned by people who have studied it closely would be downright apocalyptic: a decimated US power grid, and up to 90 percent of Americans dead within a year. It doesn’t help, either, that North Korea recently invoked the specter of an EMP attack, and seems increasingly like it would have the wherewithal to pull one off.

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