Dissident US diplomats call for strikes on Assad

A group of US diplomats have used a State Department channel for dissident views to criticise President Barack Obama's Syria policy, a spokesman confirmed Thursday.

The official would not discuss the contents of the cable, but the New York Times and Wall Street Journal said the dissenters called for US strikes against the Syrian regime.

News of the critical cable came as the Pentagon warned that Assad's Russian allies have bombed US-backed rebels.

"We are aware of a dissent channel cable written by a group of State Department employees regarding the situation in Syria," State Department spokesman John Kirby told AFP.

"We are reviewing the cable now, which came up very recently," he added.

The department's "Dissent Channel" allows diplomats who disagree with an official policy line to register their concerns with senior staff without fear of retribution.

Kirby said US Secretary of State John Kerry "values and respects" the dissent channel, but would not be drawn on whether he believes this specific complaint has merit.

According to the New York Times, which said it had seen a draft of the memo, the diplomats call for the US military to directly target Bashar al-Assad's regime.

US forces are engaged in Syria but are assisting local militias to fight the Islamic State group, not confronting Assad's Russian and Iranian-backed forces.

With only seven months left in office and a clear aversion to getting bogged down in Middle East conflicts, Obama has shown little appetite for such action.

The memo, according to the Times, calls for "a judicious use of stand-off and air weapons" - in other words cruise missiles, drones and perhaps direct US airstrikes.

With only seven months left in office and a clear aversion to getting bogged down in Middle East conflicts, Obama has shown little appetite for such action.

But the administration's alternative policy - to work with Russia to secure a ceasefire in Syria's civil war and talks on a political transition - has made little headway.

The Journal report said the memo was signed by 51 mid-to high-level State Department officials.

Meanwhile Russia on Thursday bombed US-backed fighters in southern Syria, according to a US official in Washington, who said the aggressive action by Moscow raises "serious concern."

"Today, Russian aircraft conducted a series of airstrikes near al-Tanf against Syrian Counter-ISIL forces that included individuals who have received US support," said the official using another acronym for the Islamic State, who requested anonymity.

"Russian aircraft have not been active in this area of southern Syria for some time, and there were no Syrian regime or Russian ground forces in the vicinity," the official said.

"Russia's latest actions raise serious concern about Russian intentions. We will seek an explanation from Russia on why it took this action and assurances this will not happen again.‎"