Canadian nuclear physicist Stanton Friedman, who worked on a number of projects for the American aerospace corporation McDonnell Douglas, said in an interview with the British Daily Star that aliens have visited Earth several times.
According to Friedman, "there is no shadow of a doubt" that aliens have visited Earth, but governments and security services around the world hide it.
“This is being kept secret from people because it would lead to massive panic. If they (aliens) want to declare themselves, then they can easily do it, - said Friedman
The scientist also stressed that there is plenty of evidence for the existence of aliens, recalling the declassified CIA documents, which contain data on UFO sightings.
Previously, the CIA published its archive of 13 million pages of various documents. They provide data on the activities of the CIA in Vietnam, in the Korean conflict and during the Cold War. In addition, the documents talk about alleged UFO sightings and the previously classified military project Stargate, in which the Americans conducted research on supernatural human abilities.