The next great battle America faces is likely to involve cyberwarfare, Leon Panetta, the Central Intelligence Agency director, warned senators Thursday, predicting that “the next Pearl Harbor that we confront could very well be a cyberattack that cripples" America’s electrical grid and its security and financial systems.

“It’s going to take both defensive measures as well as aggressive measures to deal with that,” said Mr. Panetta, who was appearing before the Senate Armed Services Committee in a confirmation hearing for the post of secretary of defense.

Panetta, a consummate Washington insider, is expected to be confirmed easily as the successor to Defense Secretary Robert Gates, but that did not stop him from receiving a tough – if cordial – grilling from lawmakers Thursday.

His former colleagues – Panetta served in Congress from 1977 to 1993 – pressed him for specifics on US troop withdrawals in Afghanistan. These were specifics Panetta politely declined to provide, saying that any decision on precise troop levels was up to President Obama, though he did allow that he backs Mr. Obama’s plan for a “significant” drawdown starting next month.

In the wide-ranging confirmation hearing, Panetta also warned the Armed Services Committee of the ongoing dangers posed by a sizable contingent of Al Qaeda in Iraq, of the risks of indiscriminate Pentagon budget cuts, and of the consequences of a failure to oust Libyan leader Muammar Qaddafi.

“This is a time of historic change,” Panetta said. “We are no longer in the Cold War. This is the Blizzard War – a blizzard of challenges that draws on speed and intensity from rapidly developing technologies and the rising number of powers on the world stage.”

In the short term, America continues to face a tough war in Afghanistan. Panetta, who along with Mr. Gates was a member of the Iraq Study Group, says he believes the Afghan government could benefit from the same sorts of benchmarks that were instituted in Iraq. “I think that’s something that would be worth pursuing.”

Panetta – who as CIA director has stepped up the number of US drone strikes on insurgents in Pakistan – said relations with Pakistan remain “one of the most critical – and yet one of the most complicated and frustrating – relationships that we have.” He added, “They are a nuclear power and there is a danger those nuclear weapons could end up in the wrong hands.’

In Iraq, Panetta told lawmakers he believes it would be wise to support the request of Iraqi leaders for US troops to stay beyond their scheduled December pullout date, if they ask. “I have to tell you, there are a thousand Al Qaeda that are still in Iraq,” Panetta said. “It continues to be a fragile situation, and I believe that we should take whatever steps are necessary to make sure that we protect whatever progress is made there.”

He warned that while there is “no question” that Osama bin Laden’s death has damaged Al Qaeda, the terrorist organization continues to expand “nodes” of operation in Somalia, Yemen, and North Africa. “Those are areas that we have to continue to focus on,” Panetta said.

The ultimate outcome of the ongoing conflict with Libya, too, has important implications for the United States. “If Qaddafi stays, what does that mean for our national security interest, after we said he must go?” Senator Lindsey Graham ( R) of South Carolina, asked Panetta. “Do you think it kills the Arab Spring?”

“I think it sends a terrible signal to the other countries,” Panetta responded. “I think it tells them our word isn’t worth very much if we’re not willing to stick with it.”

“Couldn’t agree with you more,” said Mr. Graham. “I can’t wait to vote for you.”