That sounds like a predator or something. Or one of those smaller military surveillance drones that are still very capable (hundreds of miles ranges). I wonder why this wouldn't be cause for an immediate scramble of fighter jets just like a manned military incursion would. Which happens a lot, Russia often crosses NATO territory unannounced with nuclear-capable cold-war bombers likes the Tu-95 Bear. Every few months or so.
Perhaps there was an intercept done but it was kept secret? But the Russian incursions are always widely reported.