The drone’s-eye view over Nagorno-Karabakh defined much of the six-week war in the mountainous enclave within Azerbaijan: The video first showed soldiers below in trenches, then came blasts and smoke, then nothing. Drone strikes — targeting Armenian and Nagorno-Karabakh soldiers and destroying tanks, artillery and air defense systems — provided a huge advantage for Azerbaijan in the 44-day war and offered the clearest evidence yet of how battlefields are being transformed by unmanned attack drones rolling off assembly lines around the world. The expanding array of relatively low-cost drones can offer countries air power at a fraction of the cost of maintaining a traditional air force. The situation in Nagorno-Karabakh also underscored how drones can suddenly shift a long-standing conflict and leave ground forces highly exposed. […]