A former defence official has claimed the US has recovered technology that did not originate on Earth.
The "US may have in our possession off-world technology recovered from someone else's space program," former intelligence chief Christopher Mellon said ahead of a hearing on UFOs in Congress this week.
One of the witnesses to Congress is David Grusch, a US Air Force veteran and intelligence chief.
Mr Grusch called in June that the US and other nations have equipment of "non-human origin" to make weapons. He alleged information had been illegally withheld from Congress.
Ahead of the Congressional hearing, Mr Mellon said to NewsNation: "I expect Dave will provide some new information that we have not heard before."
Charming UK village is 'UFO hotspot' with 'NASA scientists showing interest'He continued: "The objective here, I think, and the opportunity, is for the American people to come to better understand why it is that so many in Congress actually take seriously the idea that there are UFOs, UAP (unexplained aerial phenomenon) that are violating U.S. airspace and the associated rumour, allegation, that we may have in our possession off-world technology recovered from someone else's space program."
"I've been told that we have recovered technology that did not originate on this Earth, by officials in the Department of Defense and by former intelligence officials."
Officials dispute Mr Mellon, who is the former Deputy Assistant Secretary of Defense for Intelligence to presidents George W. Bush and Bill Clinton.
An extensive report on UFO activity is due to be published in the summer, according to Dr Sean Kirkpatrick, director of the All-domain Anomaly Resolution Office (AARO) said in April.
He explained to the Senate Armed Services Subcommittee on Emerging Threats and Capabilities earlier this year that despite acknowledged UAPs (unidentified aerial phenomena) there is no evidence yet of any alien activity whatsoever.
Over 650 cases of reported UFOs are categorised into common aircraft like planes, but those that don't fit into these categories are marked by the location they are found.
"Are they attached to a national security area? Does [it] show some anomalous phenomenology that's of interest?" Dr Kirpatrick said.
On NewsNation, Mr Mellon said witnesses are in "direct conflict" with Dr KIrkpatrick's version of events. He called for an investigation by Congress.
This weeks hearing with Congress' House Oversight Committee will be led by Tennessee Republican Congressman Tim Burchett.
Mr Burchett claimed in a press release that "The Pentagon and Washington bureaucrats have kept this information hidden for decades."
Top 10 most popular paranormal beliefs - including ghosts, aliens, and witchesHe continued: "We’re finally going to shed some light on it. We’re bringing in credible witnesses who can provide public testimony because the American people deserve the truth. We’re done with the cover-ups."
Also due to testify is Ryan Graves, a former US Navy pilot who has shared his incredible encounter with a UFO.
Mr Graves, co-founder of American for Safe Aerospace, said the ways in which pilots are able to report UFOs need to be addressed
He told Fox news he plans to tell Congress: "I'll be looking to share the experiences that I had as a Navy F-18 pilot, I'll be looking to share what has progressed in this conversation since the 2014 timeframe when we first started spotting these objects, and I'll be looking to share just how big of a problem this has become for other military aviators and commercial aviators as well."
Mr Graves admits most witnessed UAPs could be a form of sophisticated from technology.