North Carolina attacks highlight the vulnerability of power grids

When Moore County, N.C., suddenly went dark last Saturday night, Mayor Carol Haney was perplexed. There'd been no storm, no warning, just darkness on what had been a festive holiday season evening. It turned out a shooting attack on two electrical substations knocked tens of thousands of people off the grid for the better part of a week.

"This beautiful part of the world gets sabotaged," said Haney. "So, it could happen to anyone. And that's probably the most frightening for everyone– that this could happen to anyone."

It could. Across the...