The Chinese balloon shot down off the South Carolina coast by the US was part of a large surveillance programme that China has been conducting for “several years,” the Pentagon said on Wednesday.
When similar balloons passed over US territory four times during the administrations of President Joe Biden and former president Donald Trump, the US did not immediately identify them as Chinese surveillance balloons, said Brig Gen Pat Ryder, the Pentagon press secretary.
Brig Gen Ryder said “subsequent intelligence analysis” allowed the US to confirm they were part of a Chinese spying effort and learnt “a lot more” about the programme.
He would not provide any new details about the earlier balloons. When pressed, Brig Gen Ryder would only say that the vessels flew over “sites that would be of interest to the Chinese”.
One of the incidents was possibly last February, when Maj Gen Kenneth Hara, the adjutant general in Hawaii, tweeted about a balloon over Kauai a year ago.
Maj Gen Hara said US Indo-Pacific Command “detected a high-altitude object floating in air in the vicinity of the Hawaiian Islands” and sent up aircraft to intercept it.
He said they confirmed it was an unmanned balloon with no identification markings.
Brig Gen Ryder declined to say whether this was one of the four previous incidents that the US had discussed.
The recent balloon was shot down by a US military fighter jet on Saturday.
The Navy and Coast Guard are still recovering pieces of the balloon off the coast of South Carolina so they can be analysed.
China claims it was a civilian balloon used for weather research and criticised the US for shooting it down.
“I can assure you this was not for civilian purposes … we are 100 per cent clear about that,” Brig Gen Ryder said on Wednesday.
Top administration officials were briefing members of Congress on the Chinese balloon surveillance programme in classified sessions on Wednesday and Thursday.
Secretary of State Antony Blinken said the US briefed dozens of countries on the programme, which officials said had been active over five continents.
“The United States was not the only target,” he said alongside visiting Nato secretary general Jens Stoltenberg.
Mr Blinken said he and Mr Stoltenberg had spoken about the “systemic and tactical challenges” that China posed to the alliance and the importance of battling them.
The foreign countries would include nations the US believes have been under surveillamce in the past, as well as Nato allies.
Mr Stoltenberg agreed on the nature of the Chinese threat, saying the balloon incident “confirms a pattern of Chinese behaviour”.
He said that Beijing had “invested heavily in new military capabilities, including different types of surveillance and intelligence platforms”.
“We have also seen increased Chinese intelligence activities in Europe,” Mr Stoltenberg said. “We just have to be vigilant.
"We need to be aware of the constant risk of Chinese intelligence and step up what we do to protect ourselves.”
- Associated Press contributed to this report
US Navy recovers Chinese balloon — in pictures
