>>9943496 (LB)
An EMP attack will destroy any electronic and electrical equipment not sufficiently hardened against such an event. Power grids and RF equipment are especially prone to this and next to impossible to harden, due to their exposed nature; The EMP will induce very large voltage transients in long wires and antennae, leading to certain destruction of attached equipment.
Some devices and facilities can be protected. See TEMPEST resistance/hardening.