The murder of the former KGB agent Alexander Litvinenko was likely to have been carried out with Vladimir Putin's knowledge, according to the US's most senior diplomat in Europe.
The latest information released by Wikileaks reveals that in a secret conversation with a French diplomat in Paris, Daniel Fried, the assistant secretary of state, questioned whether "rogue elements" in Russia's security services would have been able to carry out the hit in London four years ago without Mr Putin, who was then the Russian president, being aware, given his "attention to detail".
Mr Fried added the Russians were behaving with "increasing self-confidence to the point of arrogance". His remarks came just two weeks after Mr Litvinenko died from polonium-210 poisoning in a London hospital.
The cables refer to a meeting on 7 December 2006 between Mr Fried and Maurice Gourdault-Montagne, a senior diplomatic adviser to Jacques Chirac, France's president at the time. The conversation took place at a time of strained US-French relations after Jacques Chirac had criticised the US-led invasion of Iraq.
The revelations will likely embarrass both Mr Gourdault-Montagne – who is now France's ambassador to London – and Mr Fried, who is now a special envoy charged by Barack Obama with the task of closing down Guantanamo Bay.
Nor will the release help efforts on the part of both the Kremlin and Downing Street to move on from the Litvinenko affair and the extended diplomatic fallout it caused. The British Foreign Secretary, William Hague, visited Moscow last month.