UFOs may be ‘unfriendly’ advanced technology, according to Nasa experts.
Unidentified Flying Objects have been in popular culture since at least the 1950s.
While many believe they could be the result of alien life, some experts believe there may be other explanations and could be aircraft from hostile nations.
Dr Thomas Zurbuchen, Nasa’s longest-serving associate administrator for the Science Mission Directorate, said he remains convinced there is something out there after reading to numerous reports and speaking to witnesses, The Telegraph reported.
Although, he said it is important to question whether Chinese spy balloons might be to blame.
It comes after a US fighter pilot shot one down in February as it crossed the Atlantic.
He said: ‘The whole balloon phenomenon we cannot ignore because if we ignore what we see then we will suddenly get surprised.’
The UFO expert recently left Nasa for ETH Zurich in his home country of Switzerland.
Before leaving, he examined evidence of UFO sightings thoroughly such as a 1952 photograph of a sighting over Passaic, New Jersey.
Dr Zurbuchen added: ‘Not only did I talk to pilots, but i also talked to individuals who had sightings and they were really convinced. I really felt they told me the subjective truth. They were not lying; they were not making things up. I think they were telling me what they saw.
‘The fact that there are unexplained phenomena is not a question for me. What they are and what they mean, and how we prove they exist is something that needs more work.
‘There could be multiple explanations. If we are looking at technology, then it may not be friendly and that is something we should know. It could be technology from other places on Earth and that would be pretty scary.
‘It could be a natural phenomenon like luminescent clouds, or something we’ve never seen before, and that would be pretty interesting, or it could be…