It's the thing many Americans fear most: losing electricity. In addition to its nuclear threat, North Korea claims it has the ability to knock out our power, too, with what's called a nuclear EMP.
Former Navy Seal Dave Sears told Fox news it's a real threat.
"An electromagnetic pulse is a real thing; it's a high altitude detonation of a nuclear weapon that could cause that (power outage) among other things -- it would be absolutely devastating."
Sears says an EMP attack on North America would do damage worldwide.
"It shuts down all sorts of things including our financial systems -- the impacts would be global."
Sears says we need to convince the communist nation our retaliation would make such an attack a mistake for the North.
He says the North's recent missile tests have to be taken seriously.
"We have to start assuming these missile tests -- how do we know that they're not nuclear-tipped missiles? We have no way to know that so our response has to be adjusted to that; the calculations have completely changed."
North America’s power grids -- including the one in Texas -- are not currently protected against an EMP disruption or attack.