The United States told its citizens in Yemen on Tuesday to leave the country immediately due to the threat of "terrorist attacks," the U.S. State Department said in a statement. Britain also withdrew all staff from its embassy in Yemen's capital, Sanaa, and closed the mission until further notice.
The new measures followed a heightened security warning from Washington on Friday that prompted the closure of several Western embassies in Yemen and several U.S. missions across the Middle East and Africa.
The State Department also said it ordered non-essential U.S. government staff in Yemen to leave the country. The moves also came after at least four suspected Al-Qaida members were killed in what local tribal leaders said was a U.S. drone strike in central Yemen early on Tuesday.
"The Department urges U.S. citizens to defer travel to Yemen and those U.S. citizens currently living in Yemen to depart immediately," the statement posted on its website said.
"On August 6, 2013, the Department of State ordered the departure of non-emergency U.S. government personnel from Yemen due to the continued potential for terrorist attacks," it added.
Meanwhile, the British Foreign Office said on its website Tuesday that "due to increased security concerns, all staff in the British Embassy have been temporarily withdrawn and the Embassy will remain closed until staff are able to return," the Foreign Office said on its website.
"There is a very high threat of kidnap from armed tribes, criminals and terrorists. Be particularly vigilant during Ramadan, when tensions could be heightened," it said.
What prompted the alert?
U.S. sources said on Monday that intercepted communication between Al-Qaida leaders was one component of a broader pool of intelligence that prompted a threat alert closing U.S. embassies across the region.
The New York Times reported that embassy closures was the result of intercepted electronic communications between Ayman al-Zawahri, who replaced Osama bin Laden as head of Al-Qaida, and Nasser al-Wuhayshi, the head of Yemen-based affiliate Al-Qaida in the Arabian Peninsula (AQAP).
U.S. sources said that while some type of message between Zawahri and AQAP was intercepted recently, there were also other streams of intelligence that contributed to the security alert, which was prompted by a threat from AQAP.
"The threat picture is based on a broad range of reporting, there is no smoking gun in this threat picture," a U.S. official told Reuters on condition of anonymity.
U.S. officials said there was still no information about a specific target or location of a potential attack, but the threat to Western interests had not diminished.
The threat is just as serious now as it was on Friday when the State Department issued a worldwide travel alert, said Representative Dutch Ruppersberger, the top Democrat on the House of Representatives Intelligence Committee.
"It's a very serious threat," Ruppersberger told CNN. "I've seen the intelligence. It's a threat coming from the highest levels of Al-Qaida. And especially focused in the Arabian peninsula, Yemen and areas like that."
ABC News on Monday reported that a senior U.S. official said authorities "are frantically searching" for vehicle bombs that Al-Qaida wants to use to blow up the U.S. embassy in Yemen and possibly other embassies.
Yemen lists 25 'most wanted terrorists'
Yemen's embassy in Washington issued a statement listing 25 "most wanted terrorists" it said were planning to carry out operations in its capital Sanaa, and said it was offering a reward for information leading to their capture.
"The Yemeni government has taken all necessary precautions to secure diplomatic facilities, vital installations and strategic assets," the statement said.
Paul Pillar, a former senior CIA analyst, said it would have taken more than a piece of communication between Al-Qaida leaders for the United States to take such aggressive action as closing 19 U.S. diplomatic posts for a week.
"The fact that Zawahri would be sending such messages doesn't surprise me," Pillar said.
"Standard procedure for analysts is not to bet the farm on any one piece of intel, even if we have no doubt that this is a message from Zawahri. It's a matter of piecing together the implications of different reports, and in combination reaching judgments about the level of threat."
U.S. sources and analysts cautioned that communication between Al-Qaida and its affiliate did not necessarily mean that AQAP was taking orders from Zawahri.
"It shows Al-Qaida core still runs a global terror machine. It is a complex picture," said Bruce Riedel, a former CIA officer who now directs the Brookings Intelligence Project in Washington.
"Zawahri does not always get what he seeks but is still undisputed as bin Laden's heir," he said.
Daniel Benjamin, a former State Department counterterrorism official who is now at Dartmouth College, said the Al-Qaida affiliate in Yemen is a "worrisome threat" because it has "talented bombmakers" and likes to move quickly and does not spend as much time planning attacks as the broader Al-Qaida did.
White House spokesman Jay Carney said while core Al-Qaida had been diminished, affiliate organizations, in particular Al-Qaida in the Arabian Peninsula, had strengthened. "And we have here in Washington identified AQAP as a particularly dangerous threat for some time now," he said.
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