Any terror plans that al-Qaeda and its affiliates may have had in the pipeline are likely to be sped up in the wake of Osama bin Laden's death, counter-terrorism officials warn. Ayman al-Zawahiri, bin Laden's second-in-command, is expected to launch a strike to prove that al-Qaeda is still a force to be reckoned with, officials say. The Egyptian doctor, who also has a $25 million bounty on his head, is described as even more radical than bin Laden.
Zawahiri "has been absolutely pivotal to al-Qaeda's strategy, development, and evolution," a Georgetown terrorism expert tells the Wall Street Journal. "By no means are we dealing with a lightweight. He talks the talk and walks the walk." Counter-terrorism officials believe Zawahiri may also now have internal power struggles within al-Qaeda to contend with, although analysts say he's ruthless enough to emerge triumphant. (Read more Osama bin Laden stories.)