Defendants look from behind bars in a state security court of appeals in Sanaa February 10, 2015. [Photo/Agencies]

Bayda is the gateway to the country's south, which remains in the hands of pro-independence southerners and to the strategic oil-rich Maarib province, to the east, also still not in rebel hands.

The US Embassy in Yemen is the third in an Arab country that has closed since the turmoil of the Arab Spring began in December 2010. The other two were embassies in Damascus, Syria, and Tripoli, Libya. The embassy in Damascus was closed in February 2012 and the embassy in Tripoli was closed in July 2014.

The embassy in Yemen was operating with only a small portion of its usual diplomatic staff and had closed to the public for all but emergency services in January. It had been operating with reduced manpower since September 2014, when the State Department ordered all non-essential personnel to leave the country.

In May, 2014 the embassy in Sanaa was closed for several weeks due to heightened security threats.