WASHINGTON – On August 7, 1990, American troops set foot on Saudi Arabian sands for the first time. Precisely eight years later, hundreds of Americans were killed in the bombing of embassies across East Africa. And on Wednesday – exactly 15 years since those bombings, and the last day of Ramadan this calendar year – the United States fears a significant attack on its assets in the Arabian Peninsula.US drones continued striking Yemen on Tuesday within hours of a new State Department warning to all citizens and nonessential government personnel, asking them to leave the country “immediately” and characterizing the security threat level as “extremely high.”The United Kingdom issued a similar warning to its citizens and evacuated its entire embassy. The modest American presence on the ground of roughly 130 US employees is abiding by the evacuation call.The diplomatic corps has been airlifted out of the country and was scheduled to arrive in Germany late Tuesday night.The new warning comes after the US shut 19 of its embassies across the Middle East last week and issued a worldwide travel warning prompted by intelligence of an impending al-Qaida attack.Yemen reacted negatively to the US pullout on Tuesday, stating that “the evacuation of [US] Embassy staff serves the interests of the extremists and undermines the exceptional cooperation between Yemen and the international alliance against terrorism.”State Department spokeswoman Jen Psaki refuted that characterization. Intelligence on an “immediate, specific threat” justified the threat assessment, Psaki said, though adding that the US had no plans to evacuate all private American citizens from the poor Arab nation. “It’s inaccurate to call it an evacuation. This is a reduction in staff,” said Psaki, who reminded journalists that there has been a travel warning in place for Yemen for “about 11 years.”US intelligence agencies were tipped off to a possible plot after intercepting communication between al-Qaida in the Arabian Peninsula, or AQAP, and Ayman al- Zawahiri, Osama bin Laden’s successor as leader of the terrorist organization. Officials have said the two parties boisterously discussed the pending attack with specific dates, though not specific targets.But US intelligence officials said in June that the leaking of classified surveillance programs by Edward Snowden had led al-Qaida to reevaluate its communications protocol – and that AQAP was the first group to alter its behavior.The discrepancy has led some analysts to question al- Qaida’s motives in this recent threat stream.“Sunday could have been flagged to reveal our security weaknesses,” says Katherine Zimmerman, a senior analyst on AQAP at the American Enterprise Institute. “There’s a possibility that this could have been an intentional leak by AQAP or Zawahiri in order to see a shift in American security posture.”In the latest strike on Tuesday, a US drone fired five missiles at a car traveling in the central Maarib province, killing all four of its occupants.Yemen’s state news agency said the four men were al-Qaida terrorists. American and British officials have frequently been the targets of attempted attacks in Yemen, a country that receives infrequent attention from Western media outlets. The US embassy in Sanaa was bombed in 2008, Americans were attacked on Christmas Day in 2009 and the British ambassador to Yemen was nearly killed in 2010.In September of last year, within days of an attack on a US consulate in Benghazi, Libya, protestors easily overran the the American Embassy in Yemen, poorly protected and perched toward the bottom of a hill.AQAP has assassinated over 100 Yemeni officials and tribal leaders over the course of several months, slowly rolling back the efforts to clear the terrorist organization out of the country’s southern region.“If you’re killing all the security and intelligence officials out in these provinces, you’re blinding your opposition, and so we’re less aware of what’s happening there than we were before,” says Daniel Green, a fellow at the Washington Institute for Near East Policy. “We clear areas, but we’re not very good at holding them.”The threat level increase comes days after a series of major prison breaks in Libya, Pakistan and Iraq, including an opening of Abu Ghraib apparently coordinated by al- Qaida.“AQAP continues to attack us where we’re not looking, when we’re not looking,” Zimmerman said.