I have been looking at this topic since I was a small kid. I think the first interesting picture I remember was a disk shaped object between some large trees on the cover of some newspaper from 1979 or thereabouts I was a few years old. I spent copious amount of time researching flimsy evidence and hoaxes for the next 20 years.
Recently I stumbled upon the famous 1994 Ariel incident which has renewed my interest and found many other people describing weird events mostly pilots risking their reputation describing confronting high speed saucer or other shaped objects. I am now intrigued again, and cannot disregard these reports, especially the Ariel incident which I will not believe for a moment that has been told to the children to all say that.
But even during that occurrence the children described many weird things such as, they were blurred, the figures moved in slow motion and the glided over the grass etc, which other children also noted. It freaked them out to scare them to this day. So yeah I would love to meet these kids (grownups today) and chat to them. But even that would not explain the huge lack of actual evidence.
Either the government is many years (and I mean many as in dozens or hundreds) ahead of us, another countries is many years ahead of us, or ET's (or ET drones) are visiting our Earth. I am 100% convinced the UFO phenomenon is 100% real and happening, and possibly has been happening for a very long time. I lean heavily towards the possibility that it is an ET craft (as I also believe Ancient Astronaut theory has a whole lot to it).
Before top secret aircraft like the SR-71 Blackbird and the Stealth Fighters/Bombers were declassified, they were unknown to the public. People who got a glimpse of one of those during test flights would certainly have considered them too technologically advanced to be terrestrial craft at the time.
There are, however, eyewitness reports from apparently credible people...some backed-up by civilian and/or military radar (JAL 1628) or seemingly direct interaction at a US nuclear missile site (Malmstrom Base). Others include astronaut reports and NASA pics/vid of unidentifiable objects that appeared to be under intelligent control. Of course, "appeared to be" isn't "definitely is".
And there have been government investigations into the UFO phenomenon...the most well-known was Project Blue Book. The government would be most concerned with national security, and if certain reported craft posed a risk. And as far as we know, they don't.
The thing is, as long as the government keeps repeating that they have no evidence whatsoever showing any extraterrestrial craft are zipping around our skies, there will always be those who don't buy that, and believe there's a cover-up. The only thing most people in ufology will believe, coming from the govt., is if they announce they do know of ET craft visiting Earth.
Time will tell. Who knows...we may find out that we're not alone, and for all we know that could happen tomorrow morning, or 1,000 years from now, or never. We haven't found solid evidence of any life anywhere, besides on our own planet. Perhaps one day we will.
If there are intelligent aliens here, the foremost important question would have to be: What are their intentions? If they have malevolent intent, there's probably not much we can do about it. And frankly, I wouldn't want to know.