WASHINGTON — The world has heard a good deal in recent days from a stern, 62-year-old Egyptian doctor thought to be hiding somewhere in Pakistan.
Ayman al-Zawahri, who ascended to the top of al-Qaida after Osama bin Laden's killing in 2011, used a video speech posted in jihadi forums on July 30 to rail against U.S. treatment of detainees at Guantánamo Bay, Cuba, and pledged that his group would spare no effort to free them.
Days later, he criticized the overthrow of the Egyptian president, Mohammed Morsi, as part of a "crusader" plot to divide his native Egypt.
But it is another communication of Zawahri's — a secret correspondence between him and the leader of the al-Qaida affiliate in Yemen — that has caused deep concern inside the U.S. government about a possible terrorist plot by the group. Those fears prompted a mass closing of 19 U.S. embassies and diplomatic outposts.
Zawahri used the communication to urge the Yemeni al-Qaida leader, Nasser al-Wahishi, to carry out a large terrorist attack, and separately he had elevated Wahishi to a more important role inside al-Qaida, the New York Times reported, citing unnamed U.S. officials.
Some analysts have characterized these moves as the last, desperate acts of a leader who no longer wields the influence he once did. To others, Zawahri is wisely making plans for the future of a group he hopes can thrive long after his death.
The United States and Britain on Tuesday increased security precautions in Yemen, with Washington urging all U.S. citizens to leave the country, while ordering all "nonemergency" and some "emergency" government personnel to do the same. Britain's Foreign Office announced it had pulled its diplomatic staff out of the capital "due to increased security concerns."
The British and U.S. warnings came several hours after Yemeni military officials said that at least four men suspected of being members of al-Qaida were killed in what was described as a U.S. drone strike in the eastern Marib region of Yemen early Tuesday. It was the fourth U.S. strike in the last two weeks.
As Westerners flew out of the country, Yemeni authorities launched a wide investigation into the al-Qaida threat to multiple potential targets in the impoverished Arab nation.
The Yemeni army surrounded foreign installations, government offices and the airport with tanks and troops in the nation's capital, drawing parallels with security measures after the 2000 bombing of the USS Cole in Aden harbor that killed 17 American sailors.
Pentagon press secretary George Little said the U.S. Air Force transported State Department personnel out of Sana early Tuesday. The department said in a travel warning that it had ordered the departure of non-emergency U.S. government personnel "due to the continued potential for terrorist attacks," adding that U.S. citizens should leave immediately because of an "extremely high" security threat level.
Yemen's government criticized the evacuations in a statement from its embassy in Washington, saying the diplomatic withdrawal "serves the interests of the extremists and undermines the exceptional cooperation" between Yemen and the international community in fighting terrorism.
Yemeni officials say the drone fired a missile at a car carrying four men in the al-Arqeen district of Marib province, setting it on fire and killing them. One of the dead was believed to be Saleh Jouti, a senior al-Qaida member.
Also Tuesday, militants shot down a Yemeni military helicopter over the al-Qaida stronghold in central Yemen, officials said. The helicopter was flying from Sana to Marib province, officials said. The eight who were killed were part of a military force guarding oil installations in the province.
The CIA has kept up its drone campaign in the tribal areas of Pakistan, where U.S. spy agencies assume Zawahri is hiding. Pakistani officials vigorously deny he is anywhere in the country.
The last time the CIA thought it was close to capturing or killing him was late 2009, when a Jordanian doctor claimed to have infiltrated the highest levels of al-Qaida and said he could inform the United States about Zawahri's precise hiding spot.
But the doctor, Humam Khalil Abu-Mulal al-Bulawi, was a double agent. On Dec. 30, 2009, he blew himself up after being let onto a CIA base in Khost, Afghanistan, an attack that killed seven CIA employees.
Information from the New York Times and Associated Press was used in this report.