Project Blue Book was a FBI team that ran from 1947 until 1969. The people of America could call up and report cases of Unidentified Flying Objects, and it was the teams job to investigate these reports and establish weather or not the reports were truly unidentified. Many cases were found to be test aircraft, and various millitary test machines.
However, as available publically, the total cases reported were 12618, of which 701 of those cases were found to be unidentified. However, the FBI had to make cutbacks, and made up some bullshit that the 701 things flying around American airspace were not a risk to national security, and the team was disbanded.
The team came around after the Roswell UFO incident in 1947. The 'official' story is that the craft recovered was a high altitude weather balloon, which is a load of bullshit. The farmer who found the craft recovered a smell segment of metal, which when folded up and crinkled, would reform back into a fully flat surface.
When the internet first came around, a lot of images were floating around of the 2 alien bodies recovered from the craft, the FBI denies these bodies existed. This is despite, a doctor known to be present during the autopsy spoke years later to say the aliens communicated telapathically with him, to tell him we werent ready yet, and they will come when we are. But, that they are watching us always.
The images I mentioned above have all been wiped from the internet. Currently, reproduction images from the film The Alien Autopsy are all that pop up, or heavily distorted images of the actual image.
A few months back, the FBI opened up to the air force, and allowed pilots and airmen to come forward, tell their stories, and they declassified sections of footage taken by pilots, showing UFOs. At this stage, the government has all but confirmed the existence of aliens. Im of the belief that the US government has had contact with intelligent life, but is holding that evidence back, to stop people from having a massively negative reaction.
Some people are still skeptics, despite the evidence available. I, myself, have seen 2 UFOs in my life, and I have read reports, declassified FBI files, and the evidence is all there to be seen. The probability of us being the only intelligent life in the universe is a big fat 0. You can read the UFO and Project Blue Book files on the FBI Vault, and the declassified footage is online on most news channels.
Update, 8th September 2023:
I found out that the Pentagon launched a new site last week, which will be a central hub for all declassified UFO footage and their descriptions of their findings. The site currently has 8 videos, and 5 remain unidentified. The other 3 have been tracked via Flight Radar, and have been put down as commercial aircraft. The site is here: https://www.aaro.mil/
This website also gives US millitary, and civilian pilots the contact information to come forward with any sightings that they have footage of. This is what we've been waiting for, soon enough there wont be any denying the existance of extraterrestrial crafts and intelligent alien life. Thank you for reading.