The United States has pulled its ambassador out of Syria amid fears for his safety.
Syria responded with a tit-for-tat move by recalling its envoy to Washington.
US Ambassador to Syria Robert Ford has been an outspoken critic of President Bashar al-Assad regime’s crackdown on anti-government protesters.
The US embassy in Damascus and Ford’s diplomatic convoy have both been attacked.
He angered Syrian authorities with his support for the anti-Assad movement, including attending the funeral of one protest leader.
The UN estimates at least 3,000 people have died since the unrest began seven months ago.