Terrorism Alert Puts bin Laden's Successor Back in Spotlight Hamid Mir/Editor/Ausaf Newspaper for Daily Dawn / Reuters Osama bin Laden sits with his adviser Ayman al-Zawahiri in November 2001 For the past the two years, Ayman al-Zawahiri had been lying low. When Navy SEALs paid a visit to Abbottabad, Pakistan, in May 2011, and killed Osama bin Laden, they lethally promoted the Egyptian doctor, then bin Laden's deputy, into the role of al-Qaeda's new leader. Since then, government officials have fretted less about al-Zawahiri and the Pakistan-based remnants of bin Laden's original team than about al-Qaeda's emerging affiliates in the Middle East and North Africa, including the fearsome al-Qaeda in the Arabian Peninsula (AQAP). But it was a message from al-Zawahiri to the leader of al-Qaeda's Yemen branch ordering attacks on unknown targets, possibly including the U.S. embassy in Yemen, that triggered alarms within the Obama Administration last week. The response to al-Zawahiri's message suggests that, for all Obama's boasts about decimating al-Qaeda's "core" in Pakistan, Washington considers the group's leadership there influential and dangerous. There are also signs that al-Zawahiri, 62, is looking to assert his own relevance and control over al-Qaeda's loosely connected affiliate groups. "It would make sense that Zawahiri thinks he needs greater connectivity with AQAP," says Daniel Benjamin, who served as the State Department's top counterterrorism official until last year. If he's going to revive the global al-Qaeda brand, he needs to show that these [affiliates] are not different bits that have blown apart, but are part of a unified whole. MORE: Panic in Yemen: Terrorist Threat Shutters U.S. and U.K. Embassies Benjamin, now with the John Sloan Dickey Center for International Understanding at Dartmouth College, says Washington's degree of concern suggests something more than mere discussion of an attack on the U.S. embassy in Yemen's capital of Sana'a, something AQAP has threatened for years. "There has to be some kind of discussion about the need to create a more integrated network," Benjamin says. Indeed, a U.S. official told CNN that al-Zawahiri recently deputized AQAP's Yemeni leader, Nasir al-Wuhayshi, to be al-Qaeda's global No. 2 operative - possible evidence of an effort to expand the geographic reach of the group's leadership. By contrast, al-Qaeda's past two deputies were based in Pakistan, like most other core leaders, when they were killed by drone strikes in 2012 and 2011. If al-Zawahiri is seeking to broaden al-Qaeda's command structure, he may be compensating for his own limitations. An Egyptian radicalized by his imprisonment and torture after he tried to foment Islamic revolution there, al-Zawahiri has always lacked bin Laden's warrior panache. Bin Laden was a reputed battlefield hero in the holy war against the Soviets in Afghanistan. Al-Zawahiri worked with the Red Crescent across the border in Pakistan, treating wounded mujahedin fighters with rudimentary medicine like the use of honey to sterilize wounds. In 2011, TIME's Tim McGirk quoted an ex-militant who called al-Zawahiri "sharp-tongued" and "arrogant," and wrote that "[h]is scraggly beard, prayer callous on his forehead and thick glasses make him look more like an unpleasant and pious schoolmaster than a terrorist mastermind." After al-Zawahiri assumed control of al-Qaeda in 2011, then Defense Secretary Robert Gates suggested that he might be a less effective leader than bin Laden. The slain al-Qaeda leader, Gates said, had possessed "a peculiar charisma that I think Zawahiri does not have." MORE: State Department Global Alert Shows "New Normal" of Terrorism But if bin Laden was al-Qaeda's international icon, al-Zawahiri is its intellectual heavyweight, the author of multiple books and manifestos explaining the group's views and goals. "More than Osama bin Laden, he's been important in writing and pushing out al-Qaeda's ideology," says Seth Jones, an al-Qaeda expert with the Rand Corp. He can also be a sneering antagonist. Soon after Obama's 2008 presidential election, al-Zawahiri released an audio message calling him a "house negro" who had betrayed his father's Muslim faith, and goaded Obama to send more troops to Afghanistan, where he said stray dogs "have savored the taste of your soldiers" flesh." More recently, he has threatened to free the prisoners at the Guantánamo Bay prison camp and scolded Egypt's Muslim Brotherhood for failing to implement Shari'a when it held power in Cairo. U.S. forces have doggedly hunted al-Zawahiri, who is assumed to be living somewhere in northern Pakistan. But despite the $25 million price on his head, he's proved even more elusive than the man he replaced. Al-Zawahiri was the likely target of a 2006 drone strike on a madrasah in Pakistan's northern Bajaur region, but since then intelligence on his whereabouts has been scant. "He's a survivor," says Jones. He's out-survived Osama bin Laden. That's no small feat - and reason not to underestimate this doctor's deadly orders. MORE: Dr. al-Zawahiri, I Presume: The Hunt Begins for al-Qaeda's New Boss