They belong to us, and are setting the stage for limited disclosure. Limited in the sense that we won't be told that they are ours. The real ET's are only seen when they make mistakes. They are not infallible. The scary part is this sets the stage for a false flag attack and another vehicle to exert control over the populace. Which is what this is all about anyway.
I have read that the ones we call Greys are around 3k years ahead and have been here for 2-3 thousand years. The more advanced live outside of what we call time. They have been coming here for millions of our years and are the ones who created the life here and also placed the Moon here. Since they exist outside of our "Time" they don't have to "wait". Time is the only thing that is real. Without time this universe would fold in on its self. Flow of time is what separates the infinity of universes.
On a serious note, I did actually hear once that the SR-71 had a, still classified, electronic countermeasure device that could enable the plane to project an image of itself thousands of feet below the altitude the plane was actually flying on radar. This was to fool surface to air missiles to attack the image of the plane. When the missile reached the target the system would turn off the fake image, and the ground control would think that it destroyed the target.
But not as quickly as the aliens with their sophisticated technology and multiple swivelling eyes (possibly).
You may also want to keep in mind that some of these "UFO's" might not actually be real. I have no doubt the military can spoof radar, FLIR, and everything else you can think of. Israel has been said to be using a lot of this newer technology, i.e. spoofing and jamming, while attacking targets in Syria to evade their missile defense systems. Unless pilots seeing these UFO's have visual confirmation I am somewhat skeptical. Here's what I'm talking about https://en.m.wikipedia.org/wiki/Electronic_countermeasure
When I was 18 years old I was radar tech on Phantoms at Seymour Johnson which was a joint SAC/TAC base so we had a lot of B-52s in addition to our 75 or so Phantoms. Once in awhile while after repairing the radar on the Phantom it would become necessary to run the radar in operate a little on the ramp. Occasionally there would be a lot of B-52s up east of the base and one early evening I lit up a whole pack of B-52s over eastern North Carolina and played with them for awhile. They could clearly see me and they started spoofing like crazy sometimes looking like a giant cloud, sometimes looking like targets far offset from their position and sometimes just ethereal and untrackable. That was around 1979 so the spoofing gear now must be amazing.