The Pentagon's All Areas Anomaly Resolution Office (AARO) published a report compiling UAP investigations conducted in the US since 1945.
"Investigations at all levels of secrecy have shown that UFO reports are often the result of misperceptions of ordinary objects and natural phenomena," the report said.
The report stated that historical records do not contain evidence of the existence of aliens, and rejected claims that the US government and private firms have reverse-engineered technology allegedly belonging to aliens.
The report noted that there was no evidence pointing to the existence of UFOs and aliens, and that the existence of many books, movies, internet and social media content on the subject influenced public opinion and increased the belief in the existence of the UAP in some segments of society.
The Pentagon stated that the second volume of the report requested by Congress, which evaluates current UAP reports, is in the process of preparation.
