Russian troops are amassed close to the Ukrainian border - could this mean war, or is something else going on?
Tensions between Ukraine and Russia aren't new, particularly since the annexation of the Crimea in 2014 and fighting with separatists, backed by Russia, in eastern Ukraine.
The West has warned Russia of dire consequences if it invades Ukraine. Russia says it is not planning to and has the right to put its troops anywhere within its territory. So what is going on?
What does President Putin want and what can NATO and the West do?
Joining David Aaronovitch in The Briefing Room are:
Sarah Rainsford, BBC Moscow Correspondent
Anton Barbashin, political analyst and editorial director of Riddle Russia
Dr. Leslie Vinjamuri, Associate Professor of International Relations, School of Oriental and African Studies, also director of the US Programme at Chatham House
Orysia Lutsevych, Research Fellow and manager of the Ukraine Forum, Russia and Eurasia Programme, Chatham House
Dr Liana Fix, Russia expert, Körber Foundation, Berlin
Programme producers: John Murphy, Kirsteen Knight and Chris Flynn Studio mix by James Beard Programme Editor: Richard Vadon
Image: Ukranian servicemen on a front line near Svetlodarsk. Credit: EPA/Anatoli Stepanov