The department told all non-essential US personnel to leave Lebanon on September 6 because of fears that an American-led strike on neighbouring Syria would unleash more bloodshed in the already fragile nation.
The Obama administration threatened to launch punitive missile strikes against Syria over an August 21 chemical weapons attack, prompting a flurry of diplomatic efforts to forestall a strike.
Those efforts concluded with last week's UN Security Council resolution endorsing the elimination of Syria's chemical weapons.