(Bloomberg) -- US officials believe the high-altitude balloon now floating at 60,000 feet over the continental US is part of a broader Chinese spying program that’s seen many such devices sent over the nation, including some during the Trump administration, people familiar with the matter said.

US officials believe the balloon is maneuverable because they’ve detected it changing course, and anticipate it will likely remain in US airspace for several more days. Nonetheless, they’ve decided not to try to shoot it down for now, arguing that the risk to the public of falling debris is too high as its payload is the size of several buses.

China says the balloon is a weather-monitoring vehicle that went off course, and expressed its regret. But US officials flatly dismissed that claim based on the size of the balloon, previous Chinese espionage activity in the same vein, and private acknowledgment from Chinese officials of its true nature, the people said.

The new details offered fresh insight into an unprecedented espionage flap that forced US Secretary of State Antony Blinken to postpone a trip to Beijing that had been set for next week. This account is based on interviews with multiple people familiar with the efforts to monitor the balloons who requested anonymity to discuss intelligence matters.

Administration officials have downplayed the intelligence risk posed by the device, saying it has only limited value – and that the US took steps to further restrict intelligence that it could gather. The balloon’s flight path has taken it over areas where the US believes the Chinese already operate satellites that are better equipped to take high-resolution images of infrastructure and military bases.

They also say it poses no physical threat to military assets, US civilians on the ground, or aircraft that operate tens of thousands of feet lower in the atmosphere.

Still, officials believe that the Chinese balloons are able to photograph facilities from different angles than satellites, providing a unique advantage. The one spotted this week was lingering over Idaho and Montana, home to sensitive US nuclear missile silos and research facilities. The US also believes the Chinese have tried to buy property near the Department of Energy’s Idaho National Laboratory, where the government conducts sensitive military research and development.

The balloons can also be deployed unexpectedly – so that the US has less time to hide assets they are hoping to be kept secret – and often have infrared sensors that provide different information than satellites. Blinken said Friday the US wanted to keep talking to China but “job one” was getting the balloon away from the US.

“When conditions permit I plan to go to China but the most important thing right now in this moment is to see that this surveillance asset gets out of our airspace,” Blinken said.

The US is taking steps to protect against collection of sensitive information, and gaining insights by tracking the balloon and discerning what abilities it could have, one White House official said.

Unique Capabilities

The makers of US spy balloons say their devices have the ability to not only capture images but intercept communications, as well as extend cellular service and the range of drones and other military assets. Experts say they expect the Chinese have similar capabilities. 

“It could work in a variety of ways,” said Greg Falco, an aerospace expert at Johns Hopkins University. “They may have developed a broad spectrum receiver to intercept a variety of bands and were trying to capture side lobes of some comms coming off of a target.”

The balloon spotted this week over Montana was not the first time the US has detected Chinese balloons over their territory – with previous incursions occurring during the Trump Administration.

One top national security official from the administration of former President Donald Trump said none of the Chinese spy balloons were near sensitive sites or had payloads as large as this one appears to carry. Other senior Trump national security officials said they were not personally aware of intelligence on any Chinese surveillance balloons over the United States during Trump’s four years in office and do not believe Trump was made aware.

Unlike past cases, this balloon is now lingering over the US mainland, and continuing to move eastward. The balloon initially left US airspace on Monday, only to be detected again Tuesday over northern Idaho. President Joe Biden was briefed that day, and requested his military commanders draw up options to respond.

A senior Canadian official said they and their American counterparts became aware of the balloon as far back as last weekend when it was over Alaska. It was tracked the whole way across Canada before it entered the continental US. 

There was a debate over how to respond to the balloon, but no serious discussion about shooting it down over Canada, the official said. 

The White House said it had been on touch with the Chinese government, and Blinken called Chinese Foreign Minister Wang Yi directly on Friday to explain his decision to cancel his trip. Despite that threat, Pentagon officials – including Defense Secretary Lloyd Austin and Chairman of the Joint Chiefs of Staff Mark Milley – ultimately advised Biden against shooting the balloon down.

They expressed concern that the resulting debris could pose a risk to US citizens and property, even if the balloon were downed over a rural area in the West. Biden agreed, though the military had mobilized equipment to the area to act if he had decided to shoot down the aircraft.

“The president is always going to put the safety of Americans and the security of American people first,” White House Press Secretary Karine Jean-Pierre said Friday.

Still, the White House also refused to rule out eventually shooting the balloon out, with Jean-Pierre telling reporters that all options remained on the table. The White House began briefing lawmakers on the incident Thursday, and is working to set up additional classified sessions next week to detail what additional information they gather about the balloon. 

--With assistance from Justin Sink, Peter Martin, Katrina Manson, Brian Platt and Josh Wingrove.

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