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.
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.
“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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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 real-life drama is unfolding just outside Hollywood. Ferocious wildfires have ballooned at an “alarming speed”, in just a matter of hours. Why?
What caused the California wildfires?
There are currently three wildfires torching southern California. The causes of all three are still being investigated.
The majority (85%) of all forest fires across the United States are started by humans, either deliberately or accidentally, according to the US Forest Service.
But there is a difference between what ignites a wildfire and what allows it to spread.
However these fires were sparked, other factors have fuelled them, making them spread quickly and leaving people less time to prepare or flee.
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LA residents face ‘long and scary night ahead’
What are Santa Ana winds?
So-called Santa Ana winds are extreme, dry winds that are common in LA in colder winter months.
The California Department of Forestry and Fire Protection warned strong Santa Ana winds and low humidity are whipping up “extreme wildfire risks”.
Winds have already topped 60mph and could reach 100mph in mountains and foothills – including in areas that have barely had any rain for months.
It has been too windy to launch firefighting aircraft, further hampering efforts to tackle the blazes.
These north-easterly winds blow from the interior of Southern California towards the coast, picking up speed as they squeeze through mountain ranges that border the urban area around the coast.
They blow in the opposite direction to the normal onshore flow that carries moist air from the Pacific Ocean into the area.
The lack of humidity in the air parches vegetation, making it more flammable once a fire is started.
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0:59
Wildfires spread as state of emergency declared
The ‘atmospheric blow-dryer’ effect
The winds create an “atmospheric blow-dryer” effect that will “dry things out even further”, said Daniel Swain, a climate scientist at University of California, Los Angeles (UCLA).
The longer the extreme wind persists, the drier the vegetation will become, he said.
“So some of the strongest winds will be at the beginning of the event, but some of the driest vegetation will actually come at the end, and so the reality is that there’s going to be a very long period of high fire risk.”
What role has climate change played?
California governor Gavin Newsom said fire season has become “year-round in the state of California” despite the state not “traditionally” seeing fires at this time of year – apparently alluding to the impact of climate change.
Scientists will need time to assess the role of climate change in these fires, which could range from drying out the land to actually decreasing wind speeds.
But broadly we know that climate change is increasing the hot, dry weather in the US that parches vegetation, thereby creating the fuel for wildfires – that’s according to scientists at World Weather Attribution.
But human activities, such as forest management and ignition sources, are also important factors that dictate how a fire spreads, WWA said.
Southern California has experienced a particularly hot summer, followed by almost no rain during what should be the wet season, said Professor Alex Hall, also from UCLA.
“And all of this comes on the heels of two very rainy years, which means there is plenty of fuel for potential wildfires.
“These intense winds have the potential to turn a small spark into a conflagration that eats up thousands of acres with alarming speed – a dynamic that is only intensifying with the warmer temperatures of a changing climate.”
The flames from a fire that broke out yesterday evening near a nature reserve in the inland foothills northeast of LA spread so quickly that staff at a care home had to push residents in wheelchairs and hospital beds down the street to a car park.
A billowing cloud of black smoke loomed over the main shopping street with its fancy restaurants and designer shops, threatening to destroy what many here consider to be their slice of paradise.
It is a reminder of the destructive power of this sort of weather.
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Martha Kelner reports from Pacific Palisades
Reza, a lifelong resident of Pacific Palisades, was evacuating with what belongings he could fit in his SUV.
“This is surreal, this is unbelievable,” he said.
“I’ve lived here all my life but this is like nothing I’ve ever seen before. This is the worst of the worst.
“I’ve never seen it with these winds, we just keep praying that the direction changes. But if the direction changes it’s to the detriment of somebody else, that’s the horrible part about it all.”
January is not normally wildfire season, but these are not ordinary circumstances, the blazes being propelled by the strongest winds in southern California for more than a decade, fuelled by drought conditions.
Authorities are warning that the winds will grow stronger overnight, meaning that conditions will likely worsen before they get better.
Police and the fire department went door to door, urging people to evacuate or risk losing their lives.
On the main road out of town, there was gridlock traffic, with some abandoning their cars to flee on foot.
On Mount Holyoake Avenue, Liz Lerner, an 84-year-old with congestive heart failure, was on her driveway and visibly panicked.
“I don’t drive, and I’m by myself,” she said.
“I have no relatives, I’m 100% alone and I don’t know what to do. My father built this house in 1949, this is my family home and this is the end. I’ve never seen anything like this.”
Around the corner, another man was hosing down his multi-million dollar home in a bid to save his property from the fire bounding towards it from a nearby canyon.
“I can’t decide whether to evacuate or stay and carry on hosing down my house,” he said.
“It’s hard to know which way the flames are heading.”
Other blazes were breaking out across LA with firefighting planes grounded because of winds which are growing stronger by the hour.
More homes, neighbourhoods and lives are under threat from this perfect and petrifying storm.
Since winning re-election, president-elect Donald Trump has expressed an interest in acquiring Greenland and the Panama Canal.
Speaking at a news conference on Tuesday, Mr Trump said he could not assure reporters that military or economic coercion would not be used to try and gain control of both areas.
“I can say this, we need them for economic security,” he said.
The two locations, which are nowhere near each other geographically, pose different interests to the incoming president.
But his desire to seize them both has caused immense backlash.
Why does Trump want Greenland?
Greenland is the world’s largest island and a semiautonomous territory of Denmark. With a population of 57,000, it has been part of Denmark for 600 years.
It is also a founding member of NATO and is home to a large US military base.
Straddling the Arctic circle between the US, Russia and Europe, the island offers a unique geopolitical advantage, that America has eyed for more than 150 years.
It’s even more valuable as the Arctic opens up more to shipping and trade.
The idea of purchasing Greenland is not a new idea for Mr Trump, as it came up during his first term in office. But he has since reiterated the benefit it could have for America’s national security.
“We need greater national security purposes,” Mr Trump said. “I’ve been told that for a long time, long before I even ran.
“People really don’t even know that Denmark has any legal right to it, but if they do, they should give it up because we need it for national security.”
Mr Trump’s claim to the island coincided with a visit by his son, Donald Trump Jr, who was in Greenland filming for a documentary, Sky News US partner network, NBC News said.
As well as its location, Greenland holds rich deposits of various natural resources.
Locked inside the island are valuable rare earth minerals needed for telecommunications, as well as uranium, billions of untapped barrels of oil and a vast supply of natural gas that used to be inaccessible but is becoming less so.
Many of the same minerals are currently mostly supplied by China, so other countries such as the US are interested in tapping into available resources closer to home.
A front-row seat to the climate crisis
More than the oil, gas or minerals, Greenland has a lot of ice – and provides a front-row seat to the globe’s climate crisis.
If that ice melts, it would reshape coastlines across the globe and has the potential to dramatically shift weather patterns.
In fact, Greenland holds enough ice that if it all melts, the world’s seas would rise by 24ft (7.4m).
Greenland also influences hurricane and winter storm activity. Because of its mountains of ice, it has the power to change patterns in the jet stream, which brings storms across the globe and dictates daily weather.
Often, especially in winter, a blocking system of high pressure off Greenland causes Arctic air to plunge to the west and east, sweeping across North America and Europe, winter weather expert Judah Cohen told the Associated Press.
What effect could this have on the UK?
British politician and security expert, Mike Martin, explained on X that the seas between Greenland and the UK – which has Iceland in the middle – are “utterly vital” for NATO.
He explained that during the Cold War, the UK would often have 50 ships stationed in the area to look after the Greenland-Iceland-UK (GIUK) gap – which is the “only sensible route” that the Russian northern fleet has to get into the Atlantic Ocean.
Both the UK and Denmark continue to have a shared security interest in the gap.
The UK government website states that as part of the UK’s Arctic Policy Framework, it will continue to develop military capability in collaboration with Denmark, to allow it to operate in the region and in order to safeguard UK interests and those of its allies.
However, if overtaken by the US, this collaboration could be affected.
‘Greenland is not for sale’
Addressing Mr Trump’s comments in an interview with Danish broadcaster TV2, Danish Prime Minister Mette Frederiksen said she did not believe the US would use military or economic power to secure control over Greenland.
“Greenland is not for sale,” Ms Frederiksen said, adding: “We need to stay calm and stick to our principles.”
Referring to the US as Denmark’s “most important and closest ally” she said she welcomed the US taking a greater interest in the Arctic region, but said it would have to be done in a way that is “respectful of the Greenlandic people”.
In the past, Greenland’s Prime Minister Mute Egede has called for independence from Denmark, but said he has no interest in the island nation becoming part of the US.
While Aaja Chemnitz, a Greenlandic member of the Danish parliament, added: “Most people don’t want it.
“I think some people find it quite disrespectful. And the way it has been done, and just the fact that you’re saying that you can buy another country.”
French foreign minister Jean-Noel Barrot also weighed in on the matter, saying on Wednesday that the European Union would not let “other nations of the world attack its sovereign borders, whoever they are”.
“If you’re asking me whether I think the United States will invade Greenland, my answer is no. But have we entered into a period of time when it is survival of the fittest? Then my answer is yes,” Mr Barrot said.
Why does Trump want the Panama Canal?
The Panama Canal is a waterway that connects the Caribbean Sea with the Pacific Ocean. It acts as a shortcut route, saving time and costs for transporting goods, according to the Embassy of Panama website.
Under the Jimmy Carter administration, control of the canal was handed from the US to Panama in 1979, with the US ending its joint partnership in controlling the strategic waterway in 1999.
It is now administered by the Panama Canal Authority, an autonomous government entity, although a Hong Kong-based contractor operates two ports connected to it, NBC reported.
Mr Trump has claimed that the US is being treated unfairly when it is “overcharged” higher rates for its ships to sail the canal than those of other countries.
He claimed that Panama is in “violation” of a deal with the US and that “China is basically taking it over”.
“We gave the Panama Canal to Panama. We didn’t give it to China,” Mr Trump said on Tuesday. “They’ve abused that gift.”
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Trump takes dig at Jimmy Carter on Panama Canal
Panamanian President Jose Raul Mulino denied in a video statement last month that China has influence over the canal and shot down the idea of the US taking back authority over it.
“Every square meter of the canal belongs to Panama and will continue to be so,” he said.
Could Trump actually do it?
The incoming president has offered few details on how he might carry out his plans to grow the US footprint, even as he promised throughout the news conference to return the country to a “golden age” of improved national security and “common sense”.
If Greenland becomes independent, it could choose to become associated with the US.
One option could be to form a so-called “free association” pact with America, similar to the status of Pacific island nations Marshall Islands, Micronesia and Palau.
Mr Trump has also suggested he would impose tariffs on Denmark if it resists his offer to purchase the island.
This could make things difficult for Danish companies, particularly drugmakers like Novo Nordisk, which sells the weight loss drug Wegovy and the type 2 diabetes medicine Ozempic, according to investment magazine Barron’s.
Eswar Prasad, a professor of trade policy at Cornell University, told the magazine that the Trump administration could tailor specific tariffs to target products made by Danish companies regardless of where they are manufactured.