North Korea may very well have the ability to kill millions of Americans, without directly firing on U.S. soil. For the first time, the pariah country’s state news agency warned it could hit the U.S. with an electromagnetic pulse (EMP) onslaught, a threat that experts contend is both very real and comes with catastrophic consequences.

“The biggest danger would be shorting out of the power grid, especially on the East Coast. Imagine a situation where large sections of the U.S. had no power. Imagine New York or Washington D.C. with no power for just a week. The implications would be hard to fathom,” Harry Kazianis, Director of Defense Studies at the Center for the National Interest, told Fox News. “The casualty rates would be off the charts.”

According to Kazianis, an EMP delivered by a nuclear weapon would not just fry power grids but also carry the destructive power of an atomic device.

North Korean leader Kim Jong Un at an undisclosed location inspecting the loading of a hydrogen bomb into a new intercontinential ballistic missile.  (Korean Central News Agency/Korea News Service via AP)

“That in it of itself is going to kill thousands if not millions depending on the size of it and where it is dropped. Also, nuclear weapons carry radioactive fallout that would be spread thousands of miles through the atmosphere and oceans,” he continued. “We would be adding to such a casualty count sadly for decades thanks to cancer cases that would arise many years later.”

So how could North Korea pull off an EMP attack? A hydrogen bomb detonated at a high altitude would create an electromagnetic pulse that would knock out key infrastructure – namely prominent parts of the U.S. electrical grid.

The higher the bomb’s detonation, the wider the range of destruction. An altitude of just under 250 miles – around the orbit of the International Space Station – would annihilate electronics in majority of the mainland, including parts of neighboring Canada and Mexico, analysts have said. North Korea exhibited its capacity to reach such altitudes in satellite launches in both 2012 and 2016.