Armenia and Azerbaijan have fought over Nagorno-Karabakh many times before. The renewed fighting this week seems more serious than usual, however, with both sides deploying heavy weaponry and weighty rhetoric. As casualties on both sides mount, and as Turkey and Russia both take a close interest in the conflict, Andrew Mueller asks Siranuysh Gevogyan, Arzu Geybulla and Peter Liakhov why this is happening again – and if there is a long-term solution.