A US military operation to shoot down a Chinese “spy balloon” that had been hovering in American airspace came at a tense time for the two superpowers, whose relationship has been on rocky ground for years.
But how did the US successfully down it with a single missile – and what intelligence are they now hoping to find in the wreckage?
A vast underwater search is now taking place to find the remains of the balloon, which the United States is confident will show the Chinese were lying about its purpose above American airspace.
China has previously said it was used for meteorological research and veered off course due to high winds, and with limited “self-steering capabilities” it was unable to right itself.
Yet the Pentagon says the balloon, which was carrying sensors and surveillance equipment, was manoeuvrable and showed it could change course when it loitered over sensitive areas of Montana where nuclear warheads are siloed.
The balloon was then seen above Kansas City and later York County, where the sheriff’s department had to remind the public to not shoot at it with their own guns: “Your rifle rounds WILL NOT reach it. Be responsible. What goes up will come down, including your bullets.”
Shot with a single missile: How the US brought balloon down
The fact the US military was able to shoot the balloon down with a single missile is significant.
Missiles often pass straight through balloons because they are not solid enough to set them off.
In 1998, British, Canadian, and American forces failed to bring down a genuinely rogue meteorological balloon over the Arctic.
The Canadian air force pumped more than a thousand 20mm cannon shells into it, yet it still did not deflate.
“They are designed to hit something solid,” said Sky’s defence and security analyst Professor Michael Clarke.
“It shows some confidence and ingenuity to get it with a single missile.”
The missile could have been fused to explode exactly three seconds after it was fired, or in such a way the higher air pressure would set it off. Either way, it was not a case of “trial and error”.
During the military operation, F-15 Eagle jets from Massachusetts accompanied the F-22 Raptors, likely to deter “nosy” countries who wanted to “have a look”, said Prof Clarke.
The US was indeed so affronted secretary of state Antony Blinken abruptly cancelled a much-anticipated trip to Beijing.
“They have lost control of it as an issue because they are completely in the wrong now,” said Professor Clarke.
“They have violated airspace, it’s been shot down, surveillance equipment will be recovered, I am certain, and it will be shown to be surveillance equipment, so they will be shown to have been lying.
“And they’ve lost the Blinken visit – for the time being. The Blinken visit will go ahead, but maybe in a couple of months or more.
“They are in the wrong and the Americans can milk this as much as they choose to.”
But it’s not the first time a Chinese spy balloon has entered foreign airspace – during the Trump administration there were three similar incidents, which received comparatively little media attention at the time.
What are ‘spy balloons’ and what is their role?
China would have ‘wiped’ spy balloon remotely
It is unlikely the US would have been worried about what intelligence the balloon was gathering, said Professor Clarke.
“Missile fields in Montana are sensitive facilities, there are lots of military facilities around there,” he said.
“But there is nothing going on there you can’t get from satellites. Although they are sensitive, there is nothing new happening there.”
American aircraft began circling the balloon as soon as it first appeared, and would have been using military equipment “either to download whatever the Chinese had or to interfere with it in some way”.
“You have an aircraft circling 10,000 feet under the balloon – you are in a position to either jam all the signals it is sending or receiving or to simply suck out of it whatever it has got on it,” he added.
“The unwritten story of this little fiasco – [which] in subsequent months will come out – [is] the electronic battle that went on when the balloon was drifting over Montana.”
But he said it was likely China would have wiped the spy balloon clean so the US will probably not recover much software from the wreckage.
Instead, the hardware “will prove the Chinese had used monitoring devices, listening devices, communication signals, intelligence devices. They will be able to prove this clearly wasn’t a weather balloon”.
Finding these devices will show “the Chinese have been lying through their back teeth”.
What happens now?
With President Joe Biden making his State of the Union address on Tuesday, it is likely he will want the balloon recovered in time for him to mention the find.
So far, Mr Biden has remained relatively quiet on the operation, and has only made a short statement on the issue during his arrival at Camp David.
“I would be surprised if on Tuesday he doesn’t use this to show the sort of president he is,” said Prof Clarke.
“He is not demonstrative, he’s not hysterical, he just gets the job done.”