The intelligence community's release of the unclassified document marks one of the first times the US government has publicly acknowledged that these strange aerial sightings by Navy pilots and others are worthy of legitimate scrutiny.
"The limited amount of high-quality reporting on unidentified aerial phenomena (UAP) hampers our ability to draw firm conclusions about the nature or intent of UAP," the nine-page preliminary report says, using the Pentagon's terminology for UFOs.
But despite that challenge, the report does conclude that these objects "clearly pose a safety of flight issue and may pose a challenge to US national security.
"Safety concerns primarily center on aviators contending with an increasingly cluttered air domain. UAP would also represent a national security challenge if they are foreign adversary collection platforms or provide evidence a potential adversary has developed either a breakthrough or disruptive technology," it says.
Read more about the report here.