The 3 Chinese spy balloons spotted during the Trump administration were initially classified as UFOs

• A Chinese spy balloon seen floating over the United States was shot down on Saturday.
• Three spy balloons were seen during the Trump administration and were initially classified as UFOs.

Days after a Chinese spy balloon was shot down over the Atlantic Ocean, Pentagon officials are acknowledging the surveillance devices have been seen floating over the United States before.

In former President Donald Trump's administration, at least three surveillance balloons were detected traversing the country, officials acknowledged in a Sunday press conference. Bloomberg reported the devices were initially categorized by intelligence officials as "unidentified aerial phenomena" before being identified as balloons.

In December, the Department of Defense established the All-domain Anomaly Resolution Office to identify "unidentified anomalous phenomena" — in space, in the air, on land, or in the sea — that may threaten national security. The term UAP replaces the traditional "unidentified flying object" or UFO designation, as officials expect to evaluate anomalies "across all domains."

During his term as president, Trump promised to "take a good, strong look" at whether UFOs existed and, in 2020, the Pentagon released formerly classified footage of unexplained phenomena Trump called a "hell of a video," CBS News reported.

Trump, however, denies the balloons ever existed

In a Sunday interview with Fox News, Trump said the Biden administration lied about Chinese balloons being seen during his term because "they look so bad."

"This never happened," he said. "It would have never happened."

The Biden administration indicated intelligence regarding the Trump-era balloons came to light after he left office and has extended an offer to brief the former President on the new information available, Politico reported.

"So those balloons, so every day as a NORAD commander it's my responsibility to detect threats to North America," General Glen VanHerck, commander of the North American Aerospace Defense Command, said at the Monday briefing regarding the Trump-era balloons. "I will tell you that we did not detect those threats. And that's a domain awareness gap that we have to figure out. But I don't want to go into further detail."

General VanHerck said the intelligence community was briefed after the balloons were spotted during the Trump administration and trained to assess similar threats, which contributed to the recent balloon being detected more quickly than previous incidents.

As the latest known Chinese surveillance device floated over the country last week before being shot down off the South Carolina coast of Myrtle Beach, Trump took aim at the Biden administration, calling for officials to "SHOOT DOWN THE BALLOON!"

It is unclear if the spy balloons seen during the Trump administration were shot down, as limited details about the incidents were only made public this week. The Pentagon declined to answer Insider's questions about the sightings and representatives for Trump did not immediately respond to Insider's requests for comment.

Balloon surveillance has been utilized as far back as the 1800s, according to Al Jazeera, and was popularized during the first World War. The F-22 that took down China's surveillance balloon on Saturday used the call sign 'FRANK01' in homage to a heroic pilot from WWI, known for shooting down over a dozen enemy balloons.