Another possibility, the US knows these are foreign drones and they're leaking the videos to get the offender to stop.
Tinfoil hat time, nuclear powered drones with plasma stealth.
US supposedly stopped researching nuclear plane engines after the 60's, but they built some working ones. They might be viable now that drone tech means we don't need people around them. And as a drone, they could fly forever. They would be super dangerous to fly over land, but maybe not over water. Especially if they were designed to safely submerge if reactor conditions became dangerous. And if your vehicle is too dangerous to land on solid earth, it needs to land in water. Which might explain the multiple videos of these vehicles transitioning from air to water.
It's been known that a plasma sheath gives radar stealth since the first atmospheric re-entries. This is why spacecraft lose radio contact on the way down. But ionizing enough air takes a lot of power, or a lot of radiation.
Maybe nuclear powered plasma stealth craft aren't that crazy? It would explain the lights, which otherwise make no sense for a covert craft