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As India recovers from a blackout that left the world's second-largest country - and more than 600 million residents - in the dark, a ripple of uncertainty moved through the Federal Regulatory Commission's command center today in the U.S. The Indian crisis had some people asking about the vulnerability of America's grid.

"What people really want to know today is, can something like India happen here? So if there is an outage or some problem in the Northeast, can it actually spread all the way to California," John Wellinghoff, the commission's chairman, told ABC News. "It's very, very unlikely that ultimately would happen."

Wellinghoff said that first, the grid was divided in the middle of the nation. Engineers said that it also was monitored more closely than ever. The grid is checked for line surges 30 times a second.

Since the Northeast blackout in 2003 - the largest in the U.S., which affected 55 million - 16,000 miles of new transmission lines have been added to the grid.

And even though some lines in the Northeast are more than 70 years old, Wellinghoff said that the chances of a blackout like India's were very low.

"Yes, we have old infrastructure in many places but we are upgrading that infrastructure," he said. "I think we'll be moving toward a much more modern grid and we're doing that as rapidly as possible."

Richard Clarke, a former national security adviser and ABC News consultant, however, said that today's biggest domestic terrorism fear was a cyberattack on the grid.

"The U.S. power grid is extremely vulnerable to cyberattack," Clarke said. "The government is aware of that. Recently the government held a White House level cyberexercise in which the scenario was a cyberterrorist attack that took down the power grid."