Has the United States confirmed sightings of alien craft, or worked to reverse-engineer extraterrestrial technology?

A more than 60-page Pentagon report released Friday says no, pouring cold water on popular conspiracy theories about government cover-ups of contact with aliens.

The report was mandated by Congress, which required the submission to lawmakers of a "written report detailing the historical record of the United States government relating to unidentified anomalous phenomena (UAPs)," more commonly known as UFOs.

The Defense Department's All-domain Anomaly Resolution Office (AARO) "found no evidence" that any government investigation,  academic research or official review "has confirmed that any sighting of a UAP represented extraterrestrial technology."

Instead, "all investigative efforts, at all levels of classification, concluded that most sightings were ordinary objects and phenomena and the result of misidentification," said the report.

It also "found no empirical evidence for claims that the USG and private companies have been reverse-engineering extraterrestrial technology."

AARO said the inaccurate reverse-engineering claims are "in large part the result of circular reporting from a group of individuals who believe this to be the case, despite the lack of any evidence."

In putting together the report -- the first of two volumes -- AARO reviewed US investigative efforts since 1945, researched archives, conducted more than two dozen interviews and worked with intelligence and defense officials responsible for oversight of controlled and special access programs.

Sean Kirkpatrick, the since-retired head of AARO, told lawmakers last year that it had not identified signs of alien activity.

AARO "has found no credible evidence thus far of extraterrestrial activity, off-world technology, or objects that defy the known laws of physics," Kirkpatrick said.