Russia's President Vladimir Putin has said the West must take seriously his threat to use nuclear weapons. He has also called up 300,000 reserve troops after Ukraine's swift recapture of large amounts of territory in recent weeks.

On the Sky News Daily with Niall Paterson, our international correspondent John Sparks analyses what Mr Putin's words mean for the war in Ukraine. Also, military analyst and former Air Vice-Marshal Sean Bell explains what shape Russia's army is in, and Dr Joanna Szostek from international research group Chatham House talks about the reaction in Russia.

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