The United States has pulled its ambassador out of Syria because of what it said were credible threats to his safety after his public support for protesters led to attacks on his embassy and diplomatic convoy by supporters of President Bashar Al-Assad. Robert Ford left as a crackdown on protests and a nascent armed insurgency intensified despite Western condemnation, and more businesses and shops closed in southern Syria in the most sustained strike of the seven-month uprising. His departure signals a further deterioration of relations between Syria's rulers and Washington, which has called for Assad to step down and deepened sanctions on Damascus to include the country's small but key oil sector. “Ambassador Robert Ford was brought back to Washington as a result of credible threats against his personal safety in Syria,” State Department spokesman Mark Toner said Monday. “At this point, we can't say when he will return to Syria. It will depend on our assessment of Syrian regime-led incitement and the security situation on the ground.” Asked if the United States had any plans to expel the Syrian ambassador to Washington, Imad Moustapha, a US official said: “Not at this time.” In the central city of Homs, 140 km north of Damascus, two people were killed when troops and loyalist militiamen fired at majority Sunni Muslim districts that have been a bastion for protests and, lately, a refuge for army defectors leading armed resistance emerging there, residents said. Syria is dominated by Assad's minority Alawite sect. The killings bring to at least 10 the number of civilians killed in tank-backed assaults on districts in Homs in the last two days, activists said. A Youtube video shot by activists purportedly showed a young protester dying from gunshot that hit him while he was dragging a body off a street in al-Khalidiya district. Their comrades are heard shouting “God is greater” as the two bodies lay next to each other on the asphalt.