The US State Department said it had evacuated non-emergency personnel and family members from its embassy in the Lebanese capital Beirut, as Congress debates a military strike on neighbouring Syria.
"The Department of State drew down non-emergency personnel and family members from Embassy Beirut due to threats to US Mission facilities and personnel," a statement on the Beirut embassy's website said.
The G20 summit in St Petersburg exposed stark divisions between host Vladimir Putin and US President Obama over Syria.
War emptied the suburb of Yarmouk in southern Damascus of its people. Assad's army holds it, but their prize is a ghost town.
Even in the President's heartland of Baltimore, 95% of voters are against his policy on military intervention in Syria.