AP Explains: How big a threat is an electromagnetic attack?

When much of Venezuela was plunged into darkness after a massive blackout this week, President Nicolás Maduro blamed the power outage on an "electromagnetic attack" carried out by the U.S.

source https://www.lifetechnology.com/blogs/life-technology-news-blog/ap-explains-how-big-a-threat-is-an-electromagnetic-attack