Here’s the answer:
1) We have not encountered aliens and the odds of us finding any, or them finding us, is pretty much zero.
Even if we detected something, or vice versa, by the time one can visit the other, the civilization being visited would most likely be dead and gone. Cataclysmic volcanic and impact disasters are too frequent.
2) Any info the government has on the most advanced recon capabilities of either us or other countries, including adversaries, is classified.
So, no, you’re not getting squat. The truth is out there but you’re not going to get it.
Why do you use the strawman of "aliens"?
This is a question of national security, not aliens.
That's like finding your house has been broken into and declaring "It can't be escaped convicts because the nearest prison is 500 miles away. Therefore, let's just ignore the break-in."
No one (except for a few flakes on FR) is speculating what these UFOs are. They are saying, let's solve the puzzle. Are they Chinese, are they Russian...or something else entirely?
That's assuming they are at the same level in evolution and technology as we are.
Given how old the universe is, it's reasonable to believe that other civilizations out there could very well be thousands of years more advanced than us and have developed technology that allows them to visit anywhere in the universe they choose.
The first is we wage almost constant warfare on ourselves and we posses nuclear weapons and have used them offensively.
Any smart thinking civilization might decide this is a galactic neighborhood to avoid.