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?
Advertisement
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.
Please use Chrome browser for a more accessible video player
“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.
Please use Chrome browser for a more accessible video player
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.”
A case of the flesh-eating screwworm parasite has been detected in a person in the United States for the first time.
The parasitic flies eat cattle and other warm-blooded animals alive, with an outbreak beginning in Central America and southern Mexico late last year.
It is ultimately fatal if left untreated.
The case in the US was identified in a person from Maryland who had travelled from Guatemala.
Beth Thompson, South Dakota’s state veterinarian, told Reuters on Sunday that she was notified of the case within the last week.
A Maryland state government official also confirmed the case.
The person was treated and prevention measures were implemented, Reuters reports.
The Centres for Disease Control and Prevention (CDC) and the Maryland Department of Health did not immediately respond to requests for comment.
What is screwworm?
The female screwworm fly lays eggs in the wounds of warm-blooded animals and once hatched, hundreds of screwworm larvae use their sharp mouths to burrow through living flesh.
It can be devastating in cattle and wildlife, and has also been known to infect humans.
Treatment is onerous, and involves removing hundreds of larvae and thoroughly disinfecting wounds. They are largely survivable if treated early enough.
The confirmed case is likely to rattle the beef and cattle futures market, which has seen record-high prices because of tight supplies.
The US typically imports more than a million cattle from Mexico each year to process into beef. The screwworm outbreak could cost Texas – the biggest cattle-producing state – $1.8bn (£1.3bn) in livestock deaths, labour costs and medication expenses.
Image: A view shows a calf after being sprayed with a disinfectant spray to prevent screwworm. Pic: Reuters
The United States Department of Agriculture (USDA) has set traps and sent mounted officers along the border, but it has faced criticism from some cattle producers and market analysts for not acting faster to pursue increased fly production via a sterile fly facility.
What is a sterile fly facility?
The case also comes just one week after the US agriculture secretary, Brooke Rollins, travelled to Texas to announce plans to build a sterile fly facility there in a bid to combat the pest. Ms Rollins had pledged repeatedly to keep screwworm out of the country.
A sterile fly facility produces a large number of male flies and sterilises them – these males are then released to mate with wild female insects, which collapses the wild population over time. This method eradicated screwworm from the US in the 1960s.
Mexico has also taken efforts to limit the spread of the pest, which can kill livestock within weeks if not treated. It had started to build a $51m sterile fly production facility.
The USDA has previously said 500 million flies would need to be released weekly to push the fly back to the Darien Gap, the stretch of rainforest between Panama and Colombia.
The troops are authorised to use their weapons for self-protection.
A White House official told NBC News that despite being armed, as of Saturday night, the National Guard troops in DC are not making arrests, and will continue to work on protecting federal assets.
The troops were largely deployed from outside the state and were framed by President Trump as a concerted effort to tackle crime and homelessness in the nation’s capital.
Such deployments are not common, and are typically used in response natural disasters or civil unrest.
More from US
Democrats have bashed the deployment as partisan in nature, accusing Mr Trump of trying to exert his presidential authority through scare tactics and said his primary targets have been cities with black leadership.
Image: Armed members of the South Carolina National Guard patrol outside of Union Station. Pic: AP
Pentagon plans to deploy US army to Chicago
Yesterday it was reported that the Pentagon was drafting plans to deploy the US army in Chicago, the largest city in the state.
The governor of Illinois then accused Mr Trump of “attempting to manufacture a crisis” and “abusing his power to distract from the pain he is causing working families”.
Officials familiar with the proposals told the Washington Post that several options were being weighed up by the US defence department, including mobilising thousands of National Guard troops in Chicago as early as September.
Mr Trump had told reporters on Friday that “Chicago is a mess”, before attacking the city’s mayor, Brandon Johnson, and hinting “we’ll straighten that one out probably next”.
The governor of Illinois has accused Donald Trump of “attempting to manufacture a crisis” over reports the US president was considering deploying the military in the state.
US newspaper The Washington Post reported on Saturday that the Pentagon was drafting plans to deploy the US army in Chicago, the state capital.
It comes as part of Mr Trump’s crackdown on crime, homelessness, and illegal immigration in mainly Democrat-run cities. He recently deployed the National Guard in Washington DC.
In a statement responding to the report, governor JB Pritzker said Illinoishad “received no requests or outreach from the federal government asking if we need assistance, and we have made no requests for federal intervention”.
He added: “The safety of the people of Illinois is always my top priority.
“There is no emergency that warrants the President of the United States federalising the Illinois National Guard, deploying the National Guard from other states, or sending active duty military within our own borders.”
The governor then said: “Donald Trump is attempting to manufacture a crisis, politicise Americans who serve in uniform, and continue abusing his power to distract from the pain he is causing working families.
More on Chicago
Related Topics:
“We will continue to follow the law, stand up for the sovereignty of our state, and protect the people of Illinois.”
Officials familiar with the proposals told the Post that several options were being weighed up by the US defence department, including mobilising thousands of National Guard troops in Chicago as early as September.
The Pentagon said it would not comment on planned operations, adding: “The department is a planning organisation and is continuously working with other agency partners on plans to protect federal assets and personnel.”
Image: People protest against President Donald Trump’s use of federal law enforcement and National Guard troops in Washington DC. Pic: AP
Mr Trump, however, told reporters on Friday that “Chicago is a mess,” before attacking the city’s mayor Brandon Johnson and hinting “we’ll straighten that one out probably next”.
Mr Johnson has not yet commented on Saturday’s reports, but said on Friday that the president’s approach to tackling crime has been “uncoordinated, uncalled for and unsound”.
“There are many things the federal government could do to help us reduce crime and violence in Chicago, but sending in the military is not one of them,” he added.
It comes after around 800 National Guard troops were deployed in Washington DC earlier this month, despite the US capital’s mayor revealing crime in the capital was at its “lowest level in 30 years”.
Please use Chrome browser for a more accessible video player
1:44
What’s it like having the army on DC’s streets?
According to preliminary figures from Washington DC’s Metropolitan Police, violent crime is down 26% in 2025 – after dropping 35% in 2024 compared with 2023.
In June Mr Trump ordered 700 US Army marines and 4,000 National Guard troops to Los Angeles in California, during protests over mass immigration raids.