After Ukraine's startling counteroffensive in the war with Russia we now have an emphatic response from the Kremlin.

Vladimir Putin has ordered Russia’s first mobilisation since World War Two and threatened nuclear retaliation, insisting: “I’m not bluffing.”

So is he or not? And how will the West react?


Tom Bradby finds out what you need to know from John Ray, our correspondent in Ukraine and only a few miles from the Russia border, and our resident Russia expert Emma Burrows.