Washington, Feb.8 : US Secretary of State Hillary Clinton said Sunday that Al Qaeda has grown more "creative and flexible" since 2001.

"I don't see them as stronger. I see that they are more creative, more flexible, more agile. They evolve," said Clinton while appearing as the first guest of Candy Crowley, the new host of CNN's "State of the Union.

"The biggest nightmare that any of us have, is that one of these terrorist member organizations within this syndicate of terror will get their hands on a weapon of mass destruction," she added.

She also said nuclear-armed countries like North Korea or Iran, pose both a real or a potential threat to the world and the United States in particular.

She said that Iran's behavior in the recent past was certainly evident of their intention to launch a missile test or a missile at their perceived enemies.

Asked if Iran and North Korea have responded to Obama's offer to "extend a hand if you are willing to unclench your fist," Clinton flatly said "no."

But, she said, "engagement has brought us a lot in the last year," and that Obama's "election, and his persona combined with the approach we took of seeking to find the basis for engagement on mutual respect, and mutual interest has really created a much more open, receptive atmosphere."

Clinton also gave a tepid endorsement to Afghan president Hamid Karzai, saying that the United States works with leaders it does not agree with all the time, based on what's in America's best interest.

On two personal questions at the end of the interview, Clinton said she doesn't follow football and can't predict the winner of the Super Bowl today, and that Chelsea Clinton, who recently got engaged, doesn't yet have a dress picked out for the wedding.