LULU GARCIA-NAVARRO, HOST:
Rumors online this weekend - death, destruction, the disabling of all your electronics. But you're listening to this right now. So yup, unsurprisingly, it didn't happen. It all started with a Facebook video, now removed. NPR's Windsor Johnston reports that it claimed a Pentagon communications drill would use an electromagnetic pulse to shut down the nation's power grid.
WINDSOR JOHNSTON, BYLINE: The confusion started with this warning in a video posted on Facebook.
SHANTELLE MCBRIDE: If you're not prepared for the electronic magnetic pulse, you will be dead in three days.
JOHNSTON: Shantelle McBride and her sister, Sherene, went on to warn Facebook users of a military exercise like the world has, quote, "never seen."
MCBRIDE: It's worse than a blackout. OK. Your car's not going to work. Your phones aren't going to work. Nothing that got electricity going through it is going to work. A lot of people are going to die in America.
JOHNSTON: The McBride sisters are actually referring to a simulation, the Department of Defense communications drill rehearsing what would happen in the event of an attack on the nation's power grid. Dr. Jeffrey Lewis is a nuclear policy expert at the Middlebury Institute. He says while such an event may seem scary, an electromagnetic pulse triggered by a high altitude explosion is highly unlikely.
JEFFREY LEWIS: It's a real physical phenomenon. But there's just no reason to believe you would get this, kind of - like I say, Hunger Games scenario. You'd be much, much, much more worried about a nuclear weapon going off in a city than one going off at a high altitude.
JOHNSTON: But it's still a scenario that raises concerns. Sixteen-year-old Charlie O'Ray (ph), who's visiting Washington, D.C., says it's definitely a threat in the back of his mind.
CHARLIE O'RAY: Something like that kind of really freaks you out because being able to shut down the entire power of the United States - that's something that would affect everything we do.
JOHNSTON: The Department of Defense says the confusion likely stemmed from a memo it posted on its site detailing a three-day military drill that is set to run through tomorrow. Windsor Johnston, NPR News. Transcript provided by NPR, Copyright NPR.