on’t worry if you hear an explosion,” our Armenian guide tells us as we creep along the bombed-out streets of Martuni. “By the time you hear it, it has already missed you. You should only really worry if you hear the hum of a drone. Which you will,” he adds with a dry grin. This small town is less than two miles from the front line of a bloody battle between Armenia and Azerbaijan over the long-disputed region of Nagorno-Karabakh—an area about the size of Delaware that’s entirely within Azerbaijan and largely inhabited by ethnic Armenians. The conflict dates back...