David Grusch, an Air Force veteran and former member of the National Geospatial Intelligence Agency (NGA) and the National Reconnaissance Office (NRO), appeared on The Joe Rogan Experience podcast on Tuesday where made a series of sensational new claims.
Asked by Rogan how many biological entities he was talking about, Mr Grusch said there was "a variety, and we have a ... certain number of different things".
"But the total numbers of what's interacting with us on earth, I mean nobody knows that," he said.
"I talk to people who are familiar with the biological analysis and everything. So we have some idea, not a complete picture because it's like, you know, you're looking at it, it's like, well I don't even understand the physiology at all, it's like what the heck, it's way different."
Mr Grusch, who was a representative of the NRO to the Unidentified Aerial Phenomena (UAP) Task Force and co-lead for UAP analysis at the NGA, first went public in June claiming the US government had secretly retrieved craft of non-human origin and alien bodies — and that he had turned over "proof" of the alleged covert program to Congress and the Inspector General of the Intelligence Community (ICIG) as part of a whistleblower complaint.
While he admitted he had not seen first-hand evidence of the alleged extraterrestrial craft or bodies, Mr Grusch said he had spoken at length with dozens of senior intelligence and military officials who had allegedly come forward to him.
Comment: During the interview, Grusch said that he does have some first-hand knowledge, but has not yet been cleared to talk about it.
The following month, Mr Grusch appeared at a US congressional UFO hearing alongside Ryan Graves, a former US Navy pilot and executive director of Americans for Safe Aerospace, and David Fravor, a former high-ranking US Navy fighter pilot who claimed to have chased a "Tic Tac"-shaped UFO off the coast of San Diego in 2004.
Mr Grusch testified that he "absolutely" believes the government is in possession of UAPs as well as remains of their non-human operators.
He has claimed the government is in possession of "double digit" numbers of crashed craft, but cannot disclose the exact number.
Mr Grusch told Rogan the number of retrieved bodies was "up there as well, just like with the retrievals".
On the question of where they came from, he said, "Nobody I talked to espoused any specific origin to me. We may know that but I'm not aware of anything."
Mr Grusch said officials inside the government "did use the term extraterrestrial" but that was only "a possible origin".
But the Schumer Amendment — bipartisan legislation put forward by the Senate in July that would force the US government to disclose its UFO secrets — "specifically uses 'non-human intelligence', NHI, very deliberately because we want to catch everything, because what if some of this stuff is not ET and they're going to use that as an escape clause", Mr Grusch said.
Asked by Rogan whether there had been any "interactions" with these beings, Mr Grusch said interactions "was a sensitive subject that my interview subjects did not want to get into".
"There was water cooler talk with some people I talked to on the program," he said.
"They're like, 'Hey bro guess what I overheard in some weird meeting.' The problem with that is it's secondary information ... Those people who physically were there, were on the program, who did the thing, I brought to the Inspector General. There was some water cooler talk about that sort of thing. But I don't even want to get into it because ... there were some details provided to me but it's secondary and I don't know if that's the telephone game and I don't know if it was hyperbolised in any way in the break room so to speak."
Pressed on whether he knew when these rumoured interactions first took place, Mr Grusch said "some specific events were mentioned to me" some of which went "pretty far back — it's pretty weird".
"The interactions stuff, it's a sensitive area," he said.
"There were multiple very senior people that were concerned about talking about that kind of stuff with me. As nuts as it sounds, that was a real subject of conversation, even if it sounds like something out of Star Trek: First Contact. Once you realise the phenomenon's real, then you realise we've recovered artefacts and biologics, or dead pilots if you will, even though it's creepy to even think about that in your world view ... that is something the President and his cabinet need to disclose ... in a controlled manner."
He also strongly hinted that he had spoken with at least one US President about the phenomenon, which he said had been going on for "thousands of years".
"Are we alone? Well the answer is we're not alone," he said.
"And I know that with 100 per cent certainty, which as an intel officer you never say 100 per cent. But all things pointed towards, based on the people I talked to like [former Nevada Senator] Harry Reid, and I use him as an example but I talked to the highest of the high people you could possibly talk to, if you catch my drift."
He added, "So unless all of them are lying and they're covering up something else — which I don't even know what it would be at this point — because the phenomenon is real, it's been going on for thousands of years, people have been seeing strange things, and not everybody's mass hallucinating."
Earlier this month, the Pentagon's UFO chief announced he would step down in December after saying that several reported sightings of objects flying through the sky over the US are either the work of foreign nations or aliens, warning that the latter would be the preferred scenario.
Dr Sean Kirkpatrick, head of the All-domain Anomaly Resolution Office (AARO), announced his plans to leave after heading the department for 18 months.
After investigating more than 800 cases during his brief stint as director, Dr Kirkpatrick warned of the presence of UFOs, and although there has yet to be any hard evidence of aliens, he said the alternative was much more frightening.
"If we don't prove it's aliens, then what we're finding is evidence of other people doing stuff in our backyard," he told Politico. "And that's not good."
The office, which was established last year, has made headlines over its investigations into UFO sightings reported by military pilots and for helping detect the Chinese surveillance balloons flying over the US.
Dr Kirkpatrick himself made headlines in June when he slammed Mr Grusch. Despite being open to the idea of aliens among us, Dr Kirkpatrick testified before congress that there was "no credible evidence thus far of extraterrestrial activity" or "off-world technology".
He criticised Mr Grusch's claims as "extremely unethical and immoral", noting that the whistleblower refused multiple requests to speak with the AARO.