SECURITY: North Korea nuclear ambition hikes threat to grid

The power industry calls it a "blackstart" -- restoring electricity from the bottom up at one power plant, then another and another. It worked in Aug. 14, 2003, when a power surge left tens of thousands of people in southeastern Canada and the northeastern U.S. in the dark. But to some experts, the confrontation over North Korea's missile and nuclear weapons expansion has elevated the risk of a catastrophically different outcome, in which an atmospheric explosion of a nuclear weapon over the U.S. triggers electromagnetic pulse (EMP) shock waves attacking electricity networks and triggering a blackout worse than the 2003 outage.