Some may be aliens using physics we have not discovered yet, but most have always been here; they are as much apart of Earth’s flora and fauna as we are.
Personally I’d rather we focus on the millions of illegal aliens crossing the border than on Klingons, Jawas, or Mork from Ork.
Everything that we have discovered leads me to believe that the speed of light is an absolute limit for both information and an asymptotic limit to the speed of material things. That being said the interaction between quantum linked particles has been measured to be at least 10k times faster than light, but its useless as a way of communicating because you can’t control the direction of the collapse. Take quantum linked particles and collapse the wave on one by measuring it and say you get a down spin. The other member of the pair will have an up spin. But the direction of spin generated by looking at the particle is always random. So if you are attempting to communicate via quantum linked particles what you get is just a random binary string.
I don’t know what the future holds (otherwise I would be a lot richer), but saying that UFOs might be aliens that know different physics than our understanding is like saying here a miracle occurs