Why are Armenia and Azerbaijan back to the brink of all-out war? Dozens have been killed in a flare-up of July's tensions in the separatist Armenian-speaking enclave of Nagorno-Karabakh. This time, it has escalated with both sides declaring martial law and competing images to back up rival claims. It could escalate even further, what with Turkey jumping to Azerbaijan's defence and President Recep Tayyip Erdogan pulling no punches this time. What is Ankara's next move? What response from Russia in a standoff that pits two former Soviet republics against each other?