A nuclear electromagnetic pulse (EMP) strike could cripple the U.S. electrical grid, communications, transportation, and other critical infrastructure for months, an expert warned.

Historian William Forstchen, a New York Times bestselling author and an expert on EMPs, discussed with Fox News Digital how the U.S. – and everyday Americans – can prepare for the “existential threat” that the attack poses.

“This is a very real threat,” he said. “EMP is generated when a small nuclear weapon, 40 to 60 kilotons or about three times the size of a Hiroshima bomb, is detonated 200 miles out in space above the United States. It sets up an electrostatic discharge which cascades to the Earth’s surface, feeds into the millions of miles of wires which become antennas, feeds this into the power grid, overloads the grid and blows it out.”

Forstchen, citing Congressional reports from 2002 and 2008, said that 80%-90% of Americans would be dead a year later if an EMP strike happened.

In doing so, Trump kept a campaign promise to prioritize missile defense.

“By next term we will build a great Iron Dome over our country,” Trump said during a West Palm Beach event on June 14. “We deserve a dome…it’s a missile defense shield, and it’ll all be made in America.”

Stay safe during an emergency with these supplies.  (iStock)

Stockpile emergency supplies

Forstchen encouraged people to prepare for the potential threat by stockpiling necessities. 

“I urge every American citizen to take this seriously and prepare a little bit. I’m not talking about turning your home into a fortress,” he said. “I am saying to have a month or two worth of emergency supplies on hand.”

As a resident of Asheville, North Carolina, Forstchen said that the devastation following Hurricane Helene has been “horrific,” leaving some still homeless months following the natural disaster.

“And this is a small regional event, imagine if it was the entire United States,” he said.

Fox News Digital has reached out to the Department of Homeland Security and the Department of Defense for comment.