The helicopter swooped into one of the most inaccessible corners of the Amazon rainforest. Brazilian special forces commandos leaped from its metal skids into the caiman-inhabited waters below.

Their target, lurking in the woodland along Brazil’s Bóia River, was a hulking steel mining dredge, caught red-handed as it drilled into the riverbed, pulverising it in search of gold.

Onboard, troops from the national environmental agency, Ibama, and the federal highway police found tools typical of this illegal industry: three bottles of mercury, 10g of gold and an enormous drill bit used to pulp the riverbed below.

But a more modern contraption also caught their eye: a sleek white receiver made by Elon Musk’s satellite internet firm Starlink, which is at the centre of an intensifying showdown between Brazilian authorities and the US billionaire that last week resulted in his social network X being blocked in South America’s biggest country.

“It’s a satellite internet antenna that provides communications to this whole criminal network,” said a special forces combatant as he showed off the device his unit had seized – one of scores taken from such criminals this year.

“We find it everywhere now. Every mining dredge has at least one of them,” the police officer added of the antenna that was being used to connect the barge and its security cameras with an absentee owner in a city hundreds of miles away.

As recently as two years ago, few in the backlands of the Amazon – where high-speed internet has long been an unthinkable luxury – had heard of Starlink or SpaceX, the rocket company that is Starlink’s parent and has sent more than 6,000 low-orbit satellites into space to beam down signals to secluded spots such as this.

Today, Starlink’s antennas are everywhere: at illegal mining operations, but also in isolated Indigenous villages, jungle lodges and ranches, and even military bases scattered across a vast rainforest region larger than the EU.

Starlink claims to have more than 250,000 clients in Brazil, up from fewer than 20,000 in February 2023. Nearly 70,000 of those dishes are in the Amazon where the company operates in more than 90% of municipalities.

“Starlink is a revolution in the way it brings good quality internet connectivity to pretty much any remote place in the world,” said Pedro Doria, a prominent Brazilian tech writer. “It’s revolutionary, and I’m not sure that many people in [the political capital] Brasília understand how – especially in the Amazon – you can’t live without Starlink any more.”

Ronaldo Lemos, a tech lawyer and innovation aficionado, travelled to the rainforest region to make a programme about Starlink’s Amazon revolution for his series Expresso Futuro. He was astonished at the technology’s rapid spread as he journeyed up the Negro River towards the border with Colombia, surfing the internet as he went.

In one port, Lemos met a physiotherapist who had given up his day job, bought up as many Starlink terminals as he could find, and was moving from river town to river town selling them for three times the original price.

“[There is] this huge demand for connectivity in the region,” said Lemos. “It definitely changed the profile of the region and I think that’s a good thing,” he added, celebrating how Starlink was giving previously isolated communities access to education and business opportunities.

But Lemos returned home troubled by what he had seen.

First, he feared Starlink’s massive penetration of the region potentially gave the US company access to highly sensitive information about a resource-rich region long seen as central to Brazil’s national security and sovereignty.

“Starlink knows the location of their equipment everywhere in the Amazon and with that information and a little data mining you can actually determine positions for mineral resources,” Lemos said.

“A company like Starlink might right now know more about the Amazon and the occupation of the Amazon by human activity than the Brazilian government actually does.”

Second, Starlink’s almost complete dominance of the Amazon’s satellite internet market gave Musk huge and potentially dangerous leverage over Brazil’s government.

“The events that we’ve seen in the past few days demonstrate that unfortunately Elon Musk has become really unstable and even juvenile in the way that he is behaving,” Lemos said of the billionaire’s refusal to comply with orders from Brazil’s supreme court and often crude attacks on the country’s judges and leftwing president.

“[This] erratic behaviour [means] it’s very hard for a country to actually depend on a person like him for critical applications like connecting the Amazon and so on.”

Brazil is far from the only country where such anxieties are being voiced about overdependence on Musk.

Starlink has more than 3 million customers in nearly 100 countries. But it is in Ukraine where the technology has proved how valuable it can be to a nation state. There are more than 42,000 Starlink terminals in the country where they are used by the military, doctors and energy workers and are viewed as a core piece of infrastructure in combating the Russian invasion.

In 2022, months after the conflict began, Musk threatened to stop covering the cost of operating Starlink in Ukraine, but he backtracked quickly. There have been multiple reports of tensions between Starlink and the Ukrainian military over the boundaries of its use, including an incident where Musk refused to enable a Ukrainian drone sub attack on the Russian fleet in Sevastopol.

“You never want to be reliant on one vendor regardless of who it is,” said Dmitri Alperovitch, an expert in cybersecurity and chair of the Silverado Policy Accelerator thinktank. However, there is no global rival to Starlink. Countries could at least follow the example of the US government in contracting with Starlink’s military arm, Starshield, where the US owns and controls the satellites, said Alperovitch.

Last year the New York Times reported that Taiwan, concerned about threats to undersea internet cables, had held talks with SpaceX about using Starlink but the discussions were hampered by concerns that Musk may come under pressure from Beijing to cut the service. China is a vital market for Tesla, the electric carmaker where Musk is CEO and in which he owns a 13% stake.

Makena Young, a fellow at the Center for Strategic and International Studies thinktank in Washington DC, said Starlink was in a unique position.

While it was not unusual for large companies to have a geopolitical impact, she said, it was “rare for them to make significant political decisions, the attention and implications of which are likely to swell when led by highly visible and potentially polarising individuals”.

When competition for Starlink finally emerges – with Amazon among the companies developing potential rivals – the Musk factor could play a role in which service customers choose.

Lemos said he hoped the tussle between Musk and Brazil’s supreme court would serve as “a wake-up call for all democracies” and urged the Brazilian government to seek other providers who could offer low-orbit satellite connectivity in the Amazon.

Lemos claimed Musk’s weaponisation of X had made it increasingly clear how the billionaire was using his social network as “a partisan foreign interference tool that tries to stir up division”. He highlighted the entrepreneur’s amplification of far-right content during the UK riots.

“My fear is that Starlink might become part of that same plot.”