Throughout the conflict, and especially since the Kremlin doubled down on its support for Assad in September 2015, Russia has pursued a win-at-all-costs strategy, which has regularly defied the bounds of modern warfare and edged Assad’s regime towards a winning position on the battlefield.

Ruthless means have justified an end that Putin sees as being closer than ever. Since the chemical attack last Tuesday, blamed on Assad’s air force by the US, Britain, France and Syria’s opposition, Russia has given the regime cover. Both sides co-ordinated a response and stuck to it, blaming an al-Qaida stockpile for the carnage, despite no evidence in the town of Khan Sheikhun that any such thing existed there.

Rather than moderate its stance, Russia has dug in further, deploying diplomats to claim Washington is in bed with terrorists and mobilising state-run troll factories to shape the narrative – with the same vigour as they showed before the US presidential poll in November.

There is no mood in Moscow to concede any ground on Syria to the US – and a calculation that Tillerson won’t be pushing too hard anyway. Tillerson’s claim that Russia has “failed its commitment to the international community”, and the US belief that Moscow has been lax in supervising the withdrawal of Syria’s stockpiles of sarin, are likely to be tabled at the meeting on Wednesday.