When two white vapour trails cross the sky near the front line in eastern Ukraine, it tends to mean one thing. Russian jets are about to attack.
But what happened near the city of Kostyantynivka was unprecedented. The lower trail split in two and a new object quickly accelerated towards the other vapour trail until they crossed and a bright orange flash lit up the sky.
Was it, as many believed, a Russian war plane shooting down another in so-called friendly fire 20km (12 miles) from the front line, or a Ukrainian jet shooting down a Russian plane?
Intrigued, Ukrainians soon found out from the fallen debris that they had just witnessed the destruction of Russian’s newest weapon - the S-70 stealth combat drone.
This is no ordinary drone. Named Okhotnik (Hunter), this heavy, unmanned vehicle is as big as a fighter jet but without a cockpit. It is very hard to detect and its developers claim it has “almost no analogy” in the world.
That all may be true, but it clearly went astray, and it appears the second trail seen on the video came from a Russian Su-57 jet, apparently chasing it down.