The claim by the General Staff of the Ukrainian armed forces, which came on a holiday celebrating Russia's sovereignty, is in line with Western intelligence estimates.

Since then, Russia and Ukraine have swapped dozens of prisoners of war, focusing on under-25s and the severely wounded and sick. There are hopes they could build into some of the biggest exchanges in the war that was triggered by Russia's 2022 invasion of Ukraine.

As the Ukraine war grinds on with little sign of Russian president, Vladimir Putin agreeing to a ceasefire we trace the evolution of his attitude towards Ukraine. David Aaronovitch spoke to Vitaly Shevchenko who is Russia editor for BBC Monitoring and co-presenter of the BBC’s Ukrainecast.