What to know about the suspected Chinese spy balloon

The spotting of an apparent high-altitude surveillance balloon over the U.S. mainland has quickly spiraled into a diplomatic incident. U.S. officials say the object is a Chinese spy balloon, while Chinese officials called it a “civilian airship” mainly used to track weather.

The airborne vehicle was seen over Montana, home to some of the United States’ nuclear missile silos.

A senior defense official, briefing lawmakers Friday morning about the balloon, said it “continues to linger” and is now moving southeast from Montana very slowly, according to a congressional aide who spoke on the condition of anonymity to describe the briefing. The Pentagon has a “constant fix” on the aircraft and its direction and is collecting signals and data on it, the aide said. Reports of a second device in Canada and Alaska are inaccurate, the defense official said.

Spy balloons have previously passed over the United States, but this object is unusual for loitering overhead “for an extended period of time,” defense officials say.

The first known usage of reconnaissance balloons was by the French during the Battle of Fleurus in 1794, when they were used to spy on Austrian and Dutch troops in what is now Belgium.

Here’s what you need to know about spy balloons, and about the Chinese balloon spotted over Montana.

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What is a spy balloon?

A spy balloon is just that - a balloon used for surveillance purposes. “Clearly they’re trying to fly this - this balloon over sensitive sites . . . to collect information,” the U.S. defense official said Thursday.

And spy balloons are nothing new: During the American Civil War, the Union even used hot-air balloons to track Confederate troop movements. During World War I, the photographic section of the U.S. Army Air Service used balloons to conduct surveillance and provide aerial imagery. And in the 1950s, the U.S. Air Force launched Project Genetrix, which it described as its first “large-scale, unmanned, high altitude balloon intelligence operation,” designed to take photos over “the Soviet land mass.”

Balloon surveillance activity has continued in recent years, according to U.S. officials. “Instances of this kind of balloon activity have been observed previously over the past several years,” the Pentagon’s press secretary, Brig. Gen. Patrick Ryder, said without giving further details.

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How big is the suspected spy balloon?

U.S. officials have given few specifics about the balloon, including its size. However, they have acknowledged that it is “sizable,” given that it has been visible despite being at high altitude, and they say the balloon is “large enough to cause damage from the debris field if we downed it over an area.”

The United States has “been tracking it for some time,” as the balloon entered the airspace of the U.S. mainland “a couple of days ago,” the defense official said.

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Where is the balloon?

The balloon is flying at about 60,000 feet, Ryder said at a Pentagon briefing Friday, adding that the balloon doesn’t represent a physical or military threat to people on the ground. He said the surveillance balloon, which has moved eastward from Montana, “is currently over the center of the continental United States” and is set to remain there for a few days.

Before reaching the U.S. mainland, the balloon soared above Alaska’s Aleutian Islands and Canada, The Washington Post reported, citing American officials. Canadian officials said in a statement that they were taking security steps - “including the monitoring of a potential second incident.”

The balloon’s path crosses over “a number of sensitive sites,” the U.S. defense official said, but the Pentagon is “taking steps to be extra vigilant so that we can mitigate any foreign intelligence risk.”

Similar balloons, carrying guidance systems, have been detected over Hawaii and Guam, according to U.S. intelligence officials, but this particular balloon stands out for how long it has stayed over U.S. territory.

“I think the thing that is different is the altitude and, of course, the willingness to put it over the continental United States for an extended period of time,” the defense official said, although he noted that he did not think the balloon “provides significant value” to Chinese surveillance capabilities.

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Why didn’t authorities shoot down the balloon?

Military leaders strongly advised against taking “kinetic action” - or firing at the balloon - out of concern for the safety of the civilians on the ground who could be hurt by debris, the defense official said.

“We had been looking at whether there was an option yesterday over some sparsely populated areas in Montana. But we just couldn’t buy down the risk enough to feel comfortable recommending shooting it down,” the official said, adding that the balloon posed neither a physical threat nor substantial intelligence threat.

“We’ve been observing it through multiple means, including manned aircraft,” the official said, adding that the military did have “sufficient authority” to “do anything that we need to do to protect the American people,” authority that includes legislative empowerment to use force against unmanned aircraft.

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Why might China use a spy balloon - and why it would loiter

It’s well known that the United States and China spy on each other, and the senior U.S. official said that the balloon’s capabilities did not appear to be “over and above” those of existing Chinese satellites and other tools.

The defense official said that “I can’t speculate” about whether China would have wanted the balloon to be spotted.

Professor Steve Tsang, the director of the China Institute at the SOAS University of London, said that given China’s access to advanced technology, any spy balloon probably would be of more “symbolic value, showing that the Chinese are able to send something in the air to survey U.S. military installations.”

“And they’re doing it because for decades the U.S. have been sending spy planes along the Chinese coast and sometimes over Chinese airspace to monitor the Chinese in ways that they couldn’t do very much about,” he said. “And now they can, so they are.”

Blinken’s decision to cancel his trip to China came just hours before he was scheduled to depart - an indication of how seriously the Biden administration takes the incident and hopes to avoid potential criticism for appearing soft on China.

The leaders of a House select committee on China, Reps. Mike Gallagher (R-Wis.) and Raja Krishnamoorthi (D-Ill.), said in a statement that the move showed that Beijing’s “recent diplomatic overtures do not represent a substantive change in policy” and that the threat China poses to the United States “is not confined to distant shores - it is here at home and we must act to counter this threat.”

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How has China responded to the spy-balloon accusations?

Initially, the Chinese Foreign Ministry spoke out against “speculation and sensationalizations.”


“China is a responsible country that has always strictly abided by international law and has no intention of infringing on any country’s territory and airspace. We hope that both sides can handle this together with calm and caution,” spokeswoman Mao Ning said.

Later on Friday, the Foreign Ministry said: “The airship is from China. It is a civilian airship used for research, mainly meteorological, purposes. Affected by the Westerlies and with limited self-steering capability, the airship deviated far from its planned course.”

It added, “The Chinese side regrets the unintended entry of the airship into US airspace due to force majeure.,” referring to the stipulation in international law that frees parties from liability in the event of an extraordinary, unforeseen event.

Without access to the object, it’s not possible to rule out that it is, in fact, a weather balloon, Tsang said - but this “would be hard for the U.S. to believe” because of the balloon’s proximity to sensitive military areas.

Earlier on Friday, the state-run nationalist tabloid Global Times quoted an expert as saying only the United States and China are capable of making navigable balloons of such a size.

“If the U.S. can prove that this balloon was from China with hard evidence, then it shows that China is already ahead of the U.S. in the technology of this field,” aerodynamicist Huang Zhicheng said.

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The Washington Post’s John Hudson, Cate Cadell, Yasmeen Abutaleb, Dan Lamothe and Alex Horton contributed to this report.