Ukraine's military has retaken thousands of square kilometres of territory near the north-eastern city of Kharkiv. The Russians are said to have retreated in haste and disarray, but they retaliated by shelling a large power plant, causing blackouts in Kharkiv, the country's second biggest city.

Is Ukraine's successful counter-offensive a turning point in the war? Could Ukraine win? Experts say Russia's president, Vladimir Putin, won't countenance defeat, and will escalate instead of retreating or suing for peace. Might Putin launch a tactical nuclear strike? Or use mobilisation or conscription for all-out war?

Joining David Aaronovitch in The Briefing Room are:

- Vitaliy Shevchenko, Russia editor at BBC Monitoring and co-host of the BBC's Ukrainecast podcast

Producers: Paul Connolly, Arlene Gregorius and Kirsteen Knight

Image credit: Anton Petrus/Getty Images