Zawahiri 'can't just talk about terror' Most Wanted Terrorist poster of Ayman Al-Zawahiri released by the FBI, October 10, 2001. WASHINGTON, May 3 (UPI) -- Ayman al-Zawahiri, the head of al-Qaida, must orchestrate "a significant terrorist attack" to "cement his authority," a former CIA official said. You can't just talk about terror and expect to be regarded as a terrorist mastermind. You've got to orchestrate terror," Bruce Riedel, who spent three decades at the CIA pursuing al-Qaida, told CBS News. Zawahiri took over al-Qaida after U.S. forces killed Osama bin Laden on May 2, 2011, and the terror group based in Pakistan has been hard hit by drone strikes and may not be able to pull off another large-scale attack, CBS said. Since bin Laden's death, Zawahiri has turned to audio and video messages to try to inspire strikes by al-Qaida affiliates and homegrown radicals in the United States. "Zawahiri, to cement his authority, has to carry out terror," Riedel said. He has to produce a significant terrorist attack which has his fingerprints on it. Riedel said he suspects Zawahiri is hiding in a populated area deep inside Pakistan. "This is a resourceful and smart guy, and it's important that we get him as soon as possible," Riedel said. Zawahiri teamed with bin Laden in 1998 and had served as al-Qaida's second in command before bin Laden's death. Zawahiri was involved in all the terror group's major attacks, including the Sept. 11, 2001, attacks on the United States.