The U.S. government on Friday released a landmark report, mandated by Congress, examining "unidentified aerial phenomena" witnessed by U.S. military personnel over recent years.

Driving the news: While the report found no evidence of aliens, it did find that UAPs could pose a threat to national security. The report issued by the intelligence community and the Department of Defense did not definitively determine what the military personnel saw.

• The report examined more than 140 incidents over the past two decades, but offered very few explanations for the observed phenomena.
• "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."
• It did, however, determine that the unidentified aerial phenomena (UAP) were not the result of advanced U.S. government technology.

The report offers a few possible explanations for the objects:

• The first is man-made objects littering the air, such as balloons or plastic bags.
• Ice crystals, moisture or heat inconsistencies may also appear to be flying object to cameras and sensors.
• The objects could have been designed by a foreign adversary, per the report. "China and Russia are making strides in hypersonic technology and directed energy, areas of increasing focus at the Pentagon," the Washington Post notes.

What they're saying: "In a limited number of incidents, UAP reportedly appeared to exhibit unusual flight characteristics. These observations could be the result of sensor errors, spoofing, or observer misperception and require additional rigorous analysis," the report reads.

• "Limited data and inconsistency in reporting are key challenges to evaluating UAP. No standardized reporting mechanism existed until the Navy established one in March 2019."
• "UAP pose a hazard to safety of flight and could pose a broader danger if some instances represent sophisticated collection against U.S. military activities by a foreign government or demonstrate a breakthrough aerospace technology by a potential adversary."

Why it matters via the Washington Post: "The mere existence of the report was a remarkable acknowledgment that human beings have encountered objects that perform feats we cannot explain."

The report includes the work of a Navy-led task force established by the Pentagon in August 2020 to investigate the unexplained encounters.

• It included examinations on videos, primarily captured by Navy pilots, showing close encounters with UAP. The videos were verified and released to the public by the Defense Department, reigniting the country's enduring obsession with UFOs and aliens.
• Sen. Marco Rubio (R-Fla.) was influential in commissioning the report, pushing the Senate Intelligence Committee to pass legislation requiring the Pentagon and intelligence community to provide a public analysis of the encounters.

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Read the full report.