Vice President Dick Cheney’s accusation on Thursday that Russia was using its energy resources as “blackmail” marked the first public salvo by the US in what could be a very fraught run-up to the G8 summit in St Petersburg in July, diplomats in Washington said.

Clearly US-Russian relations are under strain, but analysts differ over just how badly ties have deteriorated since President George W. Bush said famously in 2001 that he had looked into the eyes of Vladimir Putin and “got a sense of his soul”.