It's possible foreign drones might be speedy. It's implausible for them to be speedy with no visible Stonking Big Flame out the back. It's also implausible for them to accelerate really suddenly or submerge underwater without harm.
There are a million peaceful civilian purposes for this kind of propulsion technology, if that’s what this is.
Goes fast. Doesn't go slow or hover. Doesn't turn or accelerate suddenly. Doesn't swim.
Definitely drones. Quiet and exhaust free.
>Quiet and exhaust free.
Which is fairly impressive at the reported velocity of 2400mph.
What if it’s a hack? Get the enemy to think they’re seeing UFOs and maybe they’ll slip up on “mundane” foreign planes? Not a huge effect but it might only need to work once.
But the news of water ice on titan - and a huge band of it - makes me wonder if life hasn’t spawned twice (at least) in the solar system.
One thought I had was a plasma ball being generated by focusing high UV from a satellite. That fits some of the supposed behaviour.
FLIR shows a very low heat signature, though. Plasma is hot (and usually doesn't maneuver.)
The femtosecond mini plasma holograms are cold enough (on average) to touch - Fairy Lights in Femtoseconds: Aerial and Volumetric Graphics Rendered by Focused Femtosecond Laser Combined with Computational Holographic Fields - https://arxiv.org/abs/1506.06668
While maybe not exactly impossible that would require some insane UV laser power from a satellite.
Might not be space, the water disturbances could be projectors submerging.
Well a nuclear sub might have the power needed. Still insane though. :) Probably you would need several lasers too, intersecting where you want to have the plasma ball.
Thinking about the current efficiency of big lasers, a sub also has the benefit of being able to dump heat fast.