US intelligence sources tell media the balloon was spying on US and allied defence capabilities.
Image source, US Fleet Forces CommandUS intelligence sources have insisted the balloon shot down on Saturday was used by the Chinese military for spying.
Unnamed officials told the Washington Post they believed such balloons were used to collect intelligence on strategically relevant countries.
Japan, India, Taiwan and the Philippines were among those countries.
Chinese officials have already denied using such balloons for surveillance.
An official told the Washington Post that the US intelligence community believed some of the balloons were being flown from Hainan, a southern Chinese island that is home to a naval military base.
Quoting an unnamed senior Biden administration official, CBS News confirmed that the US intelligence community believed the balloon was part, in its words, of an “aerial surveillance program run by the People’s Liberation Army out of Hainan”.
On Monday, the US briefed 40 allied countries about the alleged espionage, a senior Biden administration official confirmed to CBS News.
In that briefing, Deputy Secretary of State Wendy Sherman also revealed one balloon had circumnavigated the planet in 2019, travelling over Hawaii and Florida.
According to the Biden administration official, a group of US Congressional leaders responsible for overseeing national intelligence matters, known as the Gang of Eight, will be briefed on the development on Wednesday, and Congress will be updated on Thursday,
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Last week, the Pentagon said a second Chinese spy balloon had been spotted over Costa Rica and Venezuela.
The discovery of alleged spy balloons has caused a diplomatic row between the US and China.
US Secretary of State Antony Blinken cancelled a trip to Beijing, set to take place just a few days after the balloon was first detected. It would have been the first meeting of its kind between the two countries in years.
“This is an unacceptable as well as an irresponsible action,” he said. “It’s even more irresponsible coming on the eve of a long-planned visit.”
US defence officials have previously said at least three suspected Chinese spy balloons flew over the country during Donald Trump’s presidency.
And according to US officials, the balloon shot down had flown over Alaska and Canada before appearing in the US state of Montana, which is home to a number of sensitive nuclear missile sites.
On Monday the US Navy released pictures of the debris of the balloon once it was shot out of the sky.
It was believed to have been nearly 200ft (60m) tall and officials said the debris spread over seven miles (11km) of Atlantic ocean.