Osama bin Laden's death might have changed the internal dynamic of al-Qaida, but no one really expected it would change the central mission of the terror network he directed. The announcement Thursday that Ayman al-Zawahri, the longtime second-in-command to bin Laden, would assume leadership of al-Qaida pretty much guarantees that the organization's attacks against the United States and other Western entities will continue.

Al-Zawahri is an old hand when it comes to terrorism, especially when it is employed against the United States. He's believed to have played the major role in planning the 1998 bombings of three U.S. embassies in Africa, where more than 224 civilians were killed and more than 5,000 injured. Likewise, he's suspected of organizing the suicide bombing of the USS Cole off the coast of Yemen more than a decade ago. He's pledged on numerous occasions in the past to continue to target the United States.

That apparently has not changed. A statement from al-Qaida that accompanied the communiqué about al-Zawahri's new role made that clear.

"We seek the help of God to preach the true religion," it said, "to incite the nation to get ready and fight to fulfill the duty of fighting the infidels who aggress on the land of Islam, led by America and its spoiled child Israel, to fight them with all our might." Talk like that and al-Zawahri's high profile within al-Qaida prompted the United States to offer a $25 million reward for information leading to his capture. That, incidentally, is the same amount as the reward for bin Laden.

Al-Zawahri, intelligence officials in the West and in many Muslim nations agree, has a different leadership style than bin Laden. They say he's far more detail-oriented and that he lacks the personal charisma that bound the widely dispersed elements of al-Qaida together.

There's some question, too, whether al-Zawahri will continue bin Laden's policy of large-scale attacks on the United States and other targets, or whether he will adopt a policy of more frequent but smaller attacks against what he considers opportune targets. Time will tell what path the new leader will take.

Whatever proves to be the case, U.S. and Western counterterrorism and intelligence officials will have to remain vigilant. The change in al-Qaida leadership might bring internal changes to the terrorism group. It likely will not alter the short- and long-term goals enunciated by bin Laden.

The United States, other nations in the West and Israel have long been al-Qaida's major targets. Al-Zawahri's official assumption of bin Laden's post won't change that policy, or reduce the dangers associated with it.