WASHINGTON —  Physical and cyber threats from radical Islamists dominated a Senate hearing on Wednesday, but Sen. Ron Johnson, R-Wis., raised another challenge that may be even more pressing–an electromagnetic pulse brought on by terror attacks or solar activity.

Johnson said security experts are worried the civilian world is unprepared to handle a catastrophic EMP, whether caused by America’s enemies or by the sun.

He asked Suzanne Spaulding, under-secretary for the National Protection and Programs Directorate of the Department of Homeland Security, if the U.S. was working to harden our defenses against EMP attacks.

Spaulding assured Johnson the executive branch was also taking action.

“It is certainly something that we have been focused on and working with our colleagues in the electric sector to find ways to address,” said Spaulding.

“I was recently in the U.K. at an international conference — energy infrastructure security summit — where EMPs was a clear focus of those discussions. This is something that is very much on our radar screen that we are working with them to address.”

Read More on Watchdog.org.