US top diplomat says Assad's fate in hands of Russia: Report

America's top diplomat reportedly told the UN secretary general that the fate of Bashar al-Assad is now in the hands of Russia - signalling a US realisation that it has little influence, or no desire, to determine the future of Syria.

According to Foreign Policy magazine, three diplomatic sources said Rex Tillerson, the secretary of state, admitted to Antonio Guterres last week that the Trump administration's priority in Syria was limited to defeating the Islamic State group.

'What happens to Assad is Russia's issue, not the US government's'

- Reported statement by Rex Tillerson

"What happens to Assad is Russia's issue, not the US government's," one source said Tillerson told the UN chief in last week's meeting. Tillerson's message, the official added, was that "the US government will respond to the terrorist threat", but that it is largely agnostic about "whether Assad goes or stays".

But the exchange comes three months after Tillerson said Assad must leave office because of his alleged use of chemical weapons in Khan Sheikhun, Idlib, to which the US responded with a barrage of cruise missiles against the Syrian air force - the first direct US military action against Assad's government.

According to Foreign Policy, Tillerson also said that recent confrontations between pro-Assad forces and the US in southern Tanf and northern Tabqa were intended only to protect US backed-forces fighting IS – not weaken the Assad government.

A State Department official declined to comment to the magazine on the private discussion, but insisted that the US remained "committed to the Geneva peace process" and supported a "credible political process that can resolve the question of Syria's future. Ultimately, this process, in our view, will lead to a resolution of Assad's status.

"The Syrian people should determine their country's political future through a political process," the official added.

The discussion was reported as the US president, Donald Trump, was due to hold his first face-to-face meeting with his Russian counterpart, Vladimir Putin, on the sidelines of the G20 Summit in Hamburg, Germany.