Yemen claims it has thwarted al-Qaeda plot The Yemeni government late Tuesday, however, issued a strong response to the diplomatic withdrawal, stating it recognized the safety fears of foreign governments, but that the pullout "serves the interests of the extremists." Local authorities had "taken all necessary precautions to ensure the safety and security of foreign missions," it stressed. Some 75 non-essential staff at the US embassy in Sanaa exited on a military plane, an American official told AFP on condition of anonymity. An AFP correspondent in Sanaa said concrete barriers surrounding the British embassy had been raised higher as part of increased security measures across the capital. A US-flagged passenger plane had been seen at Sanaa airport, the correspondent said. Residents meanwhile reported that two drones had overflown the capital. The United States is the only nation known to fly drones over Yemen, and the withdrawal of staff came hours after a drone strike in the country killed four alleged Al-Qaeda militants. A Yemeni defense ministry official said at least one of the men killed in the strike was a suspect thought to be planning an attack before the end of Ramadan this weekend. Britain also issued a warning to ships operating in the pirate-plagued waters of the Gulf of Aden off Yemen. According to reports, the trigger for the pullback came when US intelligence intercepted messages between Zawahiri and Nasser al-Wuhayshi, the leader of Al-Qaeda's Yemen offshoot, Al-Qaeda in the Arabian Peninsula.