SANAA The Air Force flew some U.S. diplomatic personnel out of Yemen on Tuesday and Washington told nationals to leave the country immediately after warnings of potential attacks that pushed the United States to shut missions across the Middle East. 
 
 Yemen, one of the poorest Arab countries, is the base for Al Qaeda in the Arabian Peninsula (AQAP), one of the most active branches of the network founded by Osama bin Laden, and militants have launched attacks from there against the West. 
 
 U.S. sources have told Reuters that intercepted communication between bin Laden's successor as al Qaeda leader, Ayman al-Zawahri, and the Yemen-based wing was one part of the intelligence behind their alert last week. 
 
 Britain, which has already advised for more than two years that its citizens in Yemen should "leave now", announced it was temporarily evacuating all its embassy staff. 
 
 Yemen is one of a handful of countries where Washington acknowledges targeting militants with strikes by drone aircraft. 
 
 In the latest strike on Tuesday, a U.S. drone fired five missiles at a car travelling in the central Maarib province killing all four of its occupants, local tribal leaders said. Yemen's state news agency Saba said four al Qaeda militants were killed in the attack. 
 
 The U.S. State Department's announcement urging Americans to leave the country follows a worldwide travel alert on Friday which prompted Washington to shut diplomatic missions across the Middle East and Africa. Some of its European allies have also closed their embassies in Yemen. 
 
 "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. 
 
 Previous U.S. travel warnings to Yemen had also advised citizens not travel to the country, but the language of the latest announcement appeared to reflect a more imminent threat. 
 
 State Department spokeswoman Jen Psaki said U.S. relations with Yemen remained strong despite the measures taken. 
 
 "So this was, again, just to reiterate, a response to an immediate specific threat, but we continue to work with them on a number of issues," Psaki told journalists at a news briefing in Washington. 
 
 Britain also said on Tuesday it had withdrawn all staff from its embassy in the capital Sanaa, adding there was "a very high threat of kidnap from armed tribes, criminals and terrorists". 
 
 The Netherlands advised its citizens to leave Yemen as a matter of urgency, local news agency ANP reported. 
 
 France said it had not changed its previous advisory asking citizens to "be very cautious and to move around as little as possible," Helene Conway-Mouret, junior Minister for French nationals abroad, told BFM TV. 
 
 EVACUATION 
 
 Restoring stability to Yemen - a country close to major shipping lanes and torn by regional and sectarian separatism and tribal violence as well as the al Qaeda insurgency - has been a priority for the United States. 
 
 In a statement issued in Washington, Pentagon spokesman George Little said the U.S. Air Force "transported personnel out of Sanaa, Yemen, as part of a reduction in emergency personnel" in response to a request by the State Department. 
 
 He did not specify which types of personnel were involved or where they were taken. 
 
 "The U.S. Department of Defense continues to have personnel on the ground in Yemen to support the U.S. State Department and monitor the security situation," the statement said. 
 
 Yemeni Foreign Minister Abu-Bakr al-Qirbi criticized the measures but said they would not affect relations with the United States. 
 
 "Unfortunately, these measures, although they are taken to protect their citizens, in reality they serve the goals that the terrorist elements are seeking to achieve," Qirbi told Reuters. 
 
 "Yemen had taken these threats seriously and had taken all the necessary measures to protect all the foreign missions in the country," he added. 
 
 The country's Supreme Security Committee issued a statement saying it had information al Qaeda was plotting attacks during Eid al-Fitr, this week's Muslim holiday that marks the end of the Ramadan fasting month. 
 
 The committee also published a list of 25 senior al Qaeda militants it said were being sought by security forces and offered a bounty of 5 million Yemeni riyals ($23,000) for information leading to their capture. 
 
 "Information has become available that terrorist elements of the al Qaeda network were planning to carry out terrorist acts targeting public installations and facilities, especially in a number of Yemeni provinces, in the latter days of the holy month of Ramadan and during the Eid al-Fitr holiday," it said. 
 
 STABILITY 
 
 Long-serving leader Ali Abdullah Saleh stepped down following months of protests against his rule in 2011, part of Arab uprisings that toppled three other heads of state. His replacement, Abd-Rabbu Mansour Hadi, met U.S. President Barack Obama in Washington last week. 
 
 Yemen is home to 56 of the 86 detainees still being held in Guantanamo Bay, Cuba, and security in Yemen is a key element of any deal to send them back so that Obama can fulfill a pledge to close the U.S. prison camp. 
 
 Washington's warnings last week concerned possible attacks in the region, based on intelligence including intercepted communication between al Qaeda leaders. Some officials pinpointed Yemen as the main concern. 
 
 No figures on the number of Americans in Yemen were immediately available. Washington had consistently cautioned citizens against travelling to Yemen since the protests in early 2011 that eventually forced Saleh to step down. 
 
 Al Qaeda's Yemen-based branch AQAP has been behind plots against Western targets and neighboring Saudi Arabia. It claimed responsibility for a failed attempt by a Nigerian man to blow up a Detroit-bound trans-Atlantic airliner with explosives hidden in his underwear on Christmas Day, 2009. 
 
 The United States has acknowledged killing Anwar al-Awlaki, an American citizen and al Qaeda preacher, in a drone strike in Yemen in September 2011. The Obama administration's policy allowing the killing of a U.S. citizen has been controversial. 
 
 (Additional reporting by Phil Stewart, Tabassum Zakaria, Susan Cornwell, Paul Eckert and Lesley Wroughton in Washington, Ingrid Melander in Paris, Thomas Escritt in Amsterdam; Writing by Sami Aboudi; Editing by Peter Graff and Mike Collett-White) ||||| The White House has warned the terror alert which forced US embassy closures across the Middle East and Africa could continue for another four weeks as it revealed its intelligence indicated an ongoing threat "from now until the end of August". 
 
 It was widely reported on Monday that the closures follow an intercepted communication between al-Qaida leader Ayman Zawahiri and the chief of the terrorist organization's Yemeni affiliate. 
 
 Supporters of the NSA's surveillance tactics have used the latest threat to justify their opposition to reining in the agency's domestic spying activities. But the information related to the latest threat was collected overseas under the Foreign Intelligence Surveillance Act – not the bulk surveillance programs disclosed by the Guardian and the Washington Post thanks to whistleblower Edward Snowden. 
 
 White House spokesman Jay Carney distanced himself from those linking the scare to recent debates about the agency's surveillance power in the US. 
 
 The White House and State Department also both sought to downplay the impact of the shutdown on the effectiveness of US diplomacy in the region, stressing the embassy closures should not be seen as indefinite. 
 
 "This is a temporary measure and it is out of an abundance of caution," said Carney. "We are engaged around the world and that engagement creates some risk. This decision is designed to reduce that risk but our engagement will continue." 
 
 In contrast to NSA supporters who have been quick to link the surveillance debate with the current scare, the White House sought to downplay any political implications. 
 
 "I am not going to blend those two stories together," added Carney. "We have a threat that we have advised the public about and we have a set of issues regarding the unauthorised disclosure of classified information that has led to a debate about the balance between protecting our security and maintaining privacy – I wouldn't blend the two issues." 
 
 The White House did however re-iterate its threat to boycott a planned bilateral summit with President Putin in Moscow in retaliation for its decision to grant temporary asylum to NSA whistleblower Edward Snowden. 
 
 Asked if there was any relationship between the embassy alerts and the recent NSA controversies, Marie Harf, a State Department spokeswoman, said "I can assure that in no way, at all, period, affects" the State Department's threat assessment. 
 
 While the administration did not make the link, others did. On Sunday, Rebublican senator Saxby Chambliss said the NSA had identified threats that were the most serious for years and akin to levels of "terrorist chatter" picked up before 9/11. "These [NSA] programs are controversial, we understand that," he told NBC's Meet the Press on Sunday. "But they are also very important … If we did not have these programs, then we simply would not be able to listen in on the bad guys." 
 
 Critics of the NSA surveillance programs were measured in their responses. Senator Ron Wyden, the Oregon Democract who has been a longstanding voice against the bulk collection of phone records, said the latest threat was "serious". 
 
 As a member of the Senate intelligence committee, Wyden receives classified briefings, but he added: "While I can't go into specific details, the vice chairman of the Senate intelligence committee noted yesterday that this information was collected using section 702 of the Foreign Intelligence Surveillance Act, rather than the Patriot Act. I still haven't seen any evidence that the NSA's dragnet surveillance of Americans' phone records is providing any unique value to American counterterrorism efforts." 
 
 Privacy campaigners criticised the linking of the latest terror alerts with the debate over the domestic powers of the NSA. Amie Stepanovich, a lawyer with the Electronic Privacy Information Center, said: "The NSA's choice to publish these threats at this time perpetuates a culture of fear and unquestioning deference to surveillance in the United States." 
 
 News of the fresh terror alert came as Congress looked increasingly likely to pursue fresh attempts to limit the NSA's domestic powers when it returns in September. 
 
 "The NSA takes in threat information every day. You have to ask, why now? What makes this information different?" added Stepanovich. 
 
 "Too much of what we hear from the government about surveillance is either speculation or sweeping assertions that lack corroboration. The question isn't if these programs used by this NSA can find legitimate threats, it's if the same threats couldn't be discovered in a less invasive manner. This situation fails to justify the NSA's unchecked access to our personal information." 
 
 US embassies have been closed temporarily in response to similar perceived terrorist threats, but rarely for this long. Four embassies were closed for the first anniversary of 9/11 in 2002; six African embassies were closed for 3 days in June of 1999; and 38 embassies shut for 2 days in December 1998. 
 
 "I don't want anyone to think we're leaning toward indefinite closure," Harf said, emphasizing that many of the embassies would largely have been closed or on relaxed hours due to the Eid holiday. 
 
 Harf said the threat "looks credible" in response to a question about whether it might have been a decoy once revelations of NSA surveillance became public. 
 
 "We continue to refine our assessment of the threat," Harf said. ||||| A suspected U.S. drone killed four alleged al-Qaida members in Yemen on Tuesday, as the U.S. and British embassies evacuated staff amid reports of a threatened attack by al-Qaida that has triggered temporary shutdowns of 19 American diplomatic posts across the Muslim world. 
 
 Yemeni officials have suggested al-Qaida threats to multiple potential targets in the Arabian Peninsula country in recent days, including foreign installations and government offices in the capital Sanaa as well as to the strategic Bab al-Mandeb straits at the entrance to the Red Sea to the south. 
 
 It is not clear if these reports are the same as the intelligence that led to the embassy shutdowns, reportedly instigated by an intercepted message between al-Qaida chief Ayman al-Zawahri and his deputy in Yemen about plans for a major terror attack. 
 
 The State Department on Tuesday ordered non-essential personnel at the U.S. Embassy in Yemen to leave the country. The department said in a travel warning that it had ordered the departure of non-emergency U.S. government personnel from Yemen "due to the continued potential for terrorist attacks" and said U.S. citizens in Yemen should leave immediately because of an "extremely high" security threat level. 
 
 Britain's Foreign Office also said it has evacuated all staff from its embassy in Yemen due to increased security concerns. The Foreign Office said the British Embassy staff were "temporarily withdrawn to the U.K." on Tuesday. It declined to comment further. 
 
 Meanwhile, there has been a spike in apparent U.S. drone strikes against al-Qaida leaders. The attack Tuesday was the fourth in two weeks. 
 
 Yemen 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 all of them. They believed that one of the dead is Saleh Jouti, a senior al-Qaida member. 
 
 To the west, in the capital Sanaa, residents awoke to the sound of an aircraft buzzing overhead. Officials said it was an American, and photos posted on Instagram appeared to show a P-3 Orion, a manned aircraft used for surveillance. All officials spoke anonymously as they were not authorized to brief the media. 
 
 The rare overflight of the capital came shortly before the announcements of the evacuations. 
 
 Yemeni authorities released the names of 25 wanted al-Qaida suspects on Monday, saying they were planning terrorist attacks in the capital, Sanaa, and other cities across the country. 
 
 A statement from Yemen's Interior Ministry said the suspects were going to target foreign offices and organizations, as well as Yemeni government installations in the impoverished Arab country. It said security was beefed up around embassies, ports, airports, oil installations and power stations. 
 
 Officials say potential U.S. targets in Sanaa could include the embassy and other buildings used by the United States to house personnel, as well as a military camp a few kilometers (miles) outside used by U.S. aircraft. 
 
 The Yemeni statement said security forces will pay $23,000 to anyone who comes forward with information that leads to the arrests of any of the wanted men. They included allegedly senior figures in al-Qaida's Yemen branch, including Saudi nationals Ibrahim Mohammed el-Rubaish and Ibrahim Hassan el-Assiri. 
 
 El-Rubaish was released from Guantanamo in 2006 and is believed to have played significant roles in al-Qaida's expanding offshoot in Yemen. He is a theological adviser to the group and his writings and sermons are prominent in the group's literature. 
 
 Military officials meanwhile said the threat may be related to the Bab al-Mandeb, pointing to a visit by Defense Minister Gen. Mohammed Nasser Ahmed on Sunday to Yemeni military forces positioned at the Red Sea entrance some 276 kilometers (171.5 miles) south of Sanaa. 
 
 Officials said that the visit came after intelligence that al-Qaida could be targeting foreign or Yemeni interests at the vital Red Sea corridor, which is a main thoroughfare for international shipping but also a crossing point of for smuggled weapons and illegal immigrants between east Africa and Yemen. 
 
 Ahmed urged the forces to stay "on alert against any sabotage operations aiming at destabilizing the country," according to officials. They also spoke on condition of anonymity because they were not authorized to speak to the press. 
 
 Washington considers the al-Qaida branch in Yemen to be among the terror network's most dangerous branches. The United States has also assisted Yemen's military in fighting the militants who, at one point during the country's recent political turmoil, had overrun large sections of land in the south. The group has also carried out bold assassination attacks on Yemeni security forces, killing hundreds over the past two years.
– American concern about the threat of an al-Qaeda attack is only intensifying. The State Department today ordered all non-essential government employees to leave Yemen, and it urged all American citizens there to do the same, reports Reuters. The development comes after news reports revealed that one of the key pieces of intelligence prompting all this concern were intercepted messages between al-Qaeda chief Ayman al-Zawahri and the leader of Yemen affiliate al-Qaeda in the Arabian Peninsula, Nasser al-Wuhayshi. Other developments: Drone strike: A suspected American drone strike killed four members of al-Qaeda traveling in a car in central Yemen overnight, reports the BBC. Buzzing the capital: A manned US surveillance plane was spotted flying over the capital of Sanaa, a rarity for the relatively quiet city, reports the AP. Not reopening soon: The US might keep some of its embassies and consulates closed for the entire month of August, reports the Guardian. Red Sea threat? The AP also reports that Yemeni officials are particularly concerned about an attack on the Ba al-Mandeb straits at the entrance to the Red Sea. The straits are vital to international shipping.