As Vladimir Putin warns he is willing to use any military means necessary in the war with Ukraine, Zoe Strimpel - a recent convert to chess - examines how Mr Putin is likely to play his next hand.

'The future of the world once more hangs in the balance of moves between the West and Russia,' she writes.

'The question of whether Russia really does have a strategic grandmaster at the helm - and whether the West can outmanoeuvre him - has become a matter of horrible urgency'.

Producer: Adele Armstrong Sound: Peter Bosher Production coordinator: Iona Hammond Editor: Richard Fenton-Smith