Dozens of US State Department officials have signed an internal memo protesting against US policy in Syria and calling for targeted military strikes against President Bashar al-Assad's government.
They argue the current approach is working against the Syrian opposition and helping Mr Assad to stay in power.
It was signed by 51 mid-to-high level officials who advise on Syria issues.
It is not unusual for internal "dissent cables" to be filed through State Department channels.
However, it is rare to have this number of diplomats voice opposition to a White House position.