The 49-year-old man's startling revelations in an exclusive interview with Express.co.uk also include claims other whistleblowers have been killed after trying to lift the lid on extraterrestrial activity.
We tracked him down after he made an approach to official UFO investigators about wanting to break a 27-year silence on what he saw.
The man, who says he was a third-class petty officer at a US Naval telecommunications centre during the 1980s, before more senior posts in the US Army and Navy Seals, claims to have valuable new evidence about the Bizarre Rendlesham UK UFO mass sightings, in Suffolk in 1980.
The married man, now living in Ohio, said he was based at NAS Moffett Field, in California, and he was there from February 1986 to October 1989, while also working with contacts in Silicone Valley.
He said: "I have never seen a UFO or ET or alien, however I have seen literally tens of thousand of documents confirming they are real and have visited Earth."
Asked if the files had included photographs of genuine alien crafts and beings, he said: "Yes, absolutely."
The veteran said he was now able to speak because his confidentiality agreement with the US authorities expired in 2014.
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