David Cameron has said the Russian position on Syria is "miles away from what the truth is."
He said Russia's president Vladimir Putin wants to see further evidence of the Assad regime's culpability for a recent chemical attack in Damascus - "so we will continue to provide it."
The Prime Minister also said Russia has denied saying Britain was "just a small island" but nevertheless retorted that the UK has "a big footprint" on the world stage.
The G20 summit in St Petersburg exposed stark divisions between host Vladimir Putin and US President Obama over Syria.
War emptied the suburb of Yarmouk in southern Damascus of its people. Assad's army holds it, but their prize is a ghost town.
Even in the President's heartland of Baltimore, 95% of voters are against his policy on military intervention in Syria.