Putin ally issues dire warning over Ukraine's invasion of Russia - as experts say move highlights Kremlin 'failure'

British-Russian national freed in huge prisoner swap meets Biden at White House

A British citizen freed in the biggest prisoner exchange with Russia since the Cold War has met with Joe Biden at the White House after returning to the US.

Vladimir Kara-Murza was serving a 25-year sentence for treason and had spent over two years imprisoned in Russia when he was freed along with 23 others at the start of August.

Posting a picture of Mr Kara-Murza, his wife and children, the US president said his family was "whole once more".

The freed dissident told Sky News he had no idea he was part of the prisoner swap and thought he was being led to his death as he was transferred from the Siberian prison where he was being held. 

Russian forces have destroyed a Ukrainian reconnaissance and sabotage group armed with NATO weapons in Kursk, Russian media is reporting, citing claims by unofficial sources.

Sky News cannot independently verify battlefield accounts.

Russian troops have been struggling to drive out Ukrainian forces from the Kursk region since the shock cross-border invasion last week.

The alerts warning of possible attacks - issued several minutes ago - cover several regions and the capital city of Kyiv.

'Astonishing' that major Russian response has not yet materialised

It is "astonishing" that there has been no significant Russian response to the Kursk invasion 10 days on from Ukraine's surprise attack, an ex-UN chief has said.

Mark Malloch Brown, former deputy secretary-general of the organisation, said it's likely Russia will soon launch a major deployment of troops to push back Ukrainian forces - but the invasion has revealed the internal "cumbersomeness" of Russia's "top-down" military.

"[It has] incredible difficulty responding flexibly and quickly to a challenge from any kind of threat," he told Sky News.

"And so it's astonishing that we're into the second week of this, and there hasn't been evidence yet of a major Russian redeployment of troops to push the Ukrainians back."

He added that he was sure such a move would come, but by then the Ukrainians "may have had the opportunity to dig themselves in to a point that it becomes a permanent feature of an otherwise barely moving frontline".

Mr Brown said he also believed Kyiv was "deliberately obfuscating" about what its aim was through the Kursk invasion.

"Is it to permanently hold it? Is it to change the dynamics of any ceasefire and peace negotiation? Is it to penetrate deeper, to put even more of a threat on Moscow? They are very deliberately, I think, not being explicit about this incursion's aims," he said.

-SKY NEWS