I personally worked on one of our most strategic systems and was aware in the late 60s of the need for EMP protection. Just read the link I provided and then appreciate this statement from it...
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How Likely Is An EMP Attack?
The risk-reward of a country like US, Russia, or China using a nuclear weapon as an EMP isn’t very good.
They could launch a single nuclear weapon to create an EMP burst, but the attacked country would respond with a nuclear strike on whoever the launch came from. Any EMP attack would almost immediately escalate to a full scale nuclear war.
For that reason it’s very unlikely that any country would conduct an isolated EMP attack. Knowing what the consequences would be, it makes more sense to do a full nuclear launch from the start, because that’s likely what will end up happening anyway.
SO THERE ISN'T MUCH RISK OF ANY NUCLEAR COUNTRIES USING AN EMP WEAPON ON AMERICA. (emphasis mine)
If any EMP attack is going to occur, it would most likely be by a rogue state or a terrorist group.
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Settle down...