In an era of orbital satellites so advanced that they are able to make out objects half the size of cars from space, a spy balloon might seem like a bit of a relic.
They were a prominent tool for reconnaissance during the Cold War and were even used in a more basic form for intelligence gathering in the Napoleonic Wars more than 200 years ago.
But security experts say the balloons are just the “tip of a revolution” in the development and use of new high-altitude surveillance craft, with the UK even investing millions in a project to develop spy balloons last year.
It comes as the US military on Friday said it was tracking a suspected Chinese spy balloon, described as being the size of three buses, that has been flying over northwestern America in recent days.
Image: A high-altitude balloon floats over Billings in Montana
A senior defence official said the US has “very high confidence” it is a Chinese high-altitude balloon and was flying over sensitive sites to collect information, while China has not immediately denied the balloon belonged to them.
Beijing admitted that the balloon had come from China, but insisted it was a “civilian airship” that had strayed into American airspace and that it was for meteorological and other scientific research.
US Secretary of State Antony Blinken is postponing a high-profile visit to China which had been due to begin on Sunday.
What are spy balloons?
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The devices are lightweight balloons, filled with gas, usually helium, and attached to a piece of spying equipment such as a long-range camera.
They can be launched from the ground and are sent up into the air where they can reach heights of between 60,000ft (18,000m) and 150,000ft (45,000m), above the flight paths of commercial aircraft in an area known as “near space”.
Once in the air, they travel using a mixture of air currents and pressurised air pockets, which can act as a form of steering.
Why are they still useful in the satellite era?
According to defence and security analyst Professor Michael Clarke, the biggest advantage of spy balloons over satellites are that they can study an area over a longer period of time.
Image: Professor Michael Clarke
“The advantage is they can stay in one place for a long time,” he told Sky News.
“Because of the way the Earth rotates, unless a satellite is over the Equator, you need three to five satellites going all the time to track the same spot.
“These balloons are also relatively cheap, and much easier to launch than a satellite.”
Will balloons continue to be used in future for spying?
Very much so, according to Professor Clarke.
Despite the wide use of satellite technology, countries including the UK are also focusing on the development and use of spycraft to operate in the upper atmosphere.
In August, it was announced the Ministry of Defence had agreed a £100m deal with US defence company Sierra Nevada to provide high-altitude unmanned balloons to be used for surveillance and reconnaissance.
Professor Clarke said: “(These balloons) are the very tip of the revolution for passive upper atmosphere aircraft.”
He said other defence firms, such as BAE, were working on ultralight solar-powered drones which are able to operate in the upper atmosphere and stay in place for up to 20 months.
Why have China used them now?
According to Professor Clarke, the use of these balloons, if indeed they were launched by China, will likely have been a message to the US following its decision to open new military bases in the Philippines.
“I think it’s a challenge,” he said.
“They (China) are signalling that if the US is going to come closer to them then they will be more aggressive with their surveillance.
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“It is also caused a political issue in the US now, because it will be seen as a sign of weakness not to shoot it down.
“This causes some embarrassment, but the US doesn’t need to respond.”
The balloon was spotted over Billings, Montana,on Wednesday – close to one of the US’s three nuclear missile silo fields at Malmstrom Air Force Base.
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0:19
Mao Ning, a Chinese foreign ministry spokesperson, says that those involved should be ‘cool-headed’
Military and defence leaders said they considered shooting the balloon out of the sky but decided against it due to the safety risk from falling debris.
Professor Clarke added: “I think the debris issue is a bit of an excuse. It was over one of the least densely populated areas of the US and if they needed to they could have asked everyone to stay inside.
“I don’t think they wanted to make it a bigger issue, because China are daring them to shoot it down and make it an international issue.”
Venezuela has accused Donald Trump of making a “colonial threat,” after the US president said the airspace “above and surrounding” the country should be considered closed “in its entirety”.
Mr Trumpmade the declaration amid growing tensions with president Nicolas Maduro – and as the US continues attacking boats it claims are carrying drugs from Venezuela.
He wrote on Truth Social: “To all Airlines, Pilots, Drug Dealers, and Human Traffickers, please consider THE AIRSPACE ABOVE AND SURROUNDING VENEZUELA TO BE CLOSED IN ITS ENTIRETY.”
Image: Air traffic above Venezuela on Saturday afternoon. Pic: FlightRadar24
Venezuela’s foreign affairs office called it a “colonial threat” and “illegal, and unjustified aggression,” and accused the president of threatening “the sovereignty of the national airspace… and the full sovereignty of the Venezuelan state”.
It added that Mr Trump’s words were part of a “permanent policy of aggression against our country” that breached international law and the UN Charter.
The Pentagon and the White House have so far not given any additional detail on the president’s statement, but it marks the latest escalation in tensions between the North and South American countries
Last week, the American aviation regulator warned of a “potentially hazardous situation” over Venezuela due to a “worsening security situation”.
Image: Nicolas Maduro is widely considered a dictator by the West. Pic: Reuters
Venezuela then revoked operating rights for six major airlines, which went on to suspend flights to the country.
Mr Trump warned a few days ago that land operations against alleged Venezuelan drug traffickers would begin “very soon”.
Such a move would be a major escalation in Operation Southern Spear – the US naval deployment in the Caribbean Sea and eastern Pacific that has so far attacked at least 21 vessels.
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0:59
Three killed as US strikes another alleged drug boat
Venezuela has said the attacks, which have killed more than 80 people, amount to murder.
The US has released videos of boats being targeted, but hasn’t provided evidence – such as photos of their cargo – to support the smuggling claims.
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1:41
Venezuela claims Trump creating ‘fables’ to justify ‘war’
The Pentagon has sought to justify the strikes by labelling the drug gangs as “foreign terrorist organisations” – putting them on par with the likes of al Qaeda.
It claims the boats targeted are carrying drugs bound for the US, although Sky’s chief correspondent says the final destination is likely to be Europe and West Africa.
The US is also offering a reward of $50m for the arrest of the Venezuelan president, who has been indicted in American courts on federal charges of narco-terrorism and conspiracy to import cocaine.
Mr Maduro has denied Mr Trump’s claims that he is involved in the drugs trade himself and said his counterpart wants to oust him so he can install a more sympathetic government.
Venezuelan officials have also claimed Mr Trump’s true motivation is access to the country’s plentiful oil reserves.
Mr Maduro, who has been president since 2013, has been accused of being a dictator who has cheated in elections.
“We all know that there are people out there [who] are violent and commit violent crimes,” said Patrick Withrow, sheriff of San Joaquin County.
“But these animals walked in and shot children at a children’s birthday party.”
Image: Bystanders watch at the scene of the shooting in Stockton, California. Pic: AP
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1:48
Children killed in birthday party shooting
Officers were called to the banquet hall in Stockton just before 6pm local time (2am UK time).
Around 100-150 people had gathered to celebrate a child’s birthday.
The sheriff told reporters he had been at a Thanksgiving celebration in Oregon during the incident but “put down my grandbabies to come hunt down these animals who took somebody else’s babies away from them”.
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Image: Investigators examine the scene on Sunday. Pic: AP
Image: A man walks near the remains of flares near the site of Saturday’s shooting. Pic: Bronte Wittpenn/San Francisco Chronicle/AP
He appealed for the public to send in “any little bit” of information that could lead to the arrest of the gunmen.
“If you know anything about this, you have to come forward and tell us what you know.”
There is currently nobody in custody over the incident.
Image: First responders attending. Pic: AP
Although the investigation is still under way, Sheriff Withrow said there appeared to have been “multiple shooters” who began the attack indoors and then moved outside.
The shooting was “not a random act”, he said. “They walked into this area and were probably looking for somebody in particular.”
He confirmed that guns had been found on the roof of a nearby building but it was too early to say whether they were “related to this crime”.
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Police have also towed multiple cars in the area, some damaged with bullet holes, in case they can be used as evidence.
“Please continue to give us more information,” he said, “and we will follow every single lead.”
A vigil was held for the victims on Sunday, according to local media, with the entire local council in attendance.
On Saturday, Stockton mayor Christina Fugazi said that “families should be together instead of at the hospital, standing next to their loved one, praying that they survive”.
California governor Gavin Newsom’s office added that he had been briefed on the “horrific shooting”.
Children are among the fatalities in a mass shooting at a child’s birthday party in California.
Police said four people had died and 10 were wounded in the incident in Stockton, about 60 miles east of San Francisco.
Officers were called on Saturday to a banquet hall just before 6pm local time (2am UK time) and district attorney Ron Freitas said children were among the dead.
He said the attacker was still at large.
Image: First responders walk through a parking lot near the scene of a mass shooting in Stockton, California. Pics: AP
“We can confirm at this time that approximately 14 individuals were struck by gunfire, and four victims have been confirmed deceased,” San Joaquin County Sheriff’s Office said on X.
The post said early indications suggest it could be a “targeted incident” but that information remains limited.
Police have so far not disclosed the attacker’s identity and the motive is unclear.
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Stockton’s vice mayor Jason Lee confirmed on Facebook that the shooting on Lucile Avenue happened at a child’s birthday party.
Image: Pics: AP
Mayor Christina Fugazzi also said that “families should be together instead of at the hospital, standing next to their loved one, praying that they survive”.
Californiagovernor Gavin Newsom’s office added that he had been briefed on the “horrific shooting”.