The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point, knocking out about 300 streetlights,[6] setting off numerous burglar alarms and damaging a telephone company microwave link. The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian islands. Ten deg. above the horizon 900 mules away. And that was antiquated 'analog' equipment.
New printed circuits, IC chips are much more vulnerable .