THE Pentagon has admitted it ran a secret program to investigate sightings of unidentified flying objects.
The Advanced Aviation Threat Identification Program ended five years ago, when US Defence officials shifted attention and funding to other priorities. It is not clear whether it has continued to investigate sightings of mysterious vehicles.
The program ran from 2007-12 with $A28.5 million ($US22 million) in annual funding hidden in Defence budgets worth hundreds of billions of dollars, The New York Times reported.
Initial funding came largely at the request of former Senate Democratic leader Harry Reid, the Nevada Democrat long known for his enthusiasm for space phenomena, the newspaper said.
Most of the money went to an aerospace research company run by Robert Bigelow, a billionaire entrepreneur and long-time friend of Mr Reid.
Mr Bigelow founded an institute to research fringe sciences and paranormal topics, most notably UFOs. It researched reports of black triangles "flying near cities”. It ultimately attributed them to the military.
"I'm not embarrassed or ashamed or sorry I got this thing going,” Mr Reid said.
According to its backers, the program still exists and officials to investigate UFO episodes brought to their attention by service members alongside their other duties, the paper said.
A former congressional staffer told Politico.com that the program may have been established to monitor whether a rival foreign power had developed potentially threatening next-generation technology.
"Was this China or Russia trying to do something or has some propulsion system we are not familiar with?” they asked.
The Pentagon acknowledged the existence and timeframe of the program. But it was less clear about whether it has continued.
Mr Reid tweeted: "The truth is out there. Seriously.”
He added: "If anyone says they have the answers, they're fooling themselves.”