Last week, China’s Ministry of Commerce published a document that went by the name of “announcement No. 62 of 2025”.

But this wasn’t just any bureaucratic missive. It has rocked the fragile tariffs truce with the US.

The announcement detailed sweeping new curbs on its rare earth exports, in a move that tightens Beijing’s grip on the global supply of the critical minerals – and reminded Donald Trump just how much leverage China holds in the trade war.

China has a near-monopoly in the processing of rare earths – crucial for the production of everything from smartphones to fighter jets.

Under the new rules, foreign companies now need the Chinese government’s approval to export products that contain even a tiny amount of rare earths and must declare their intended use.

In response, US President Donald Trump threatened to impose an additional 100% tariff on Chinese goods and put export controls on key software.

“This is China versus the world. They have pointed a bazooka at the supply chains and the industrial base of the entire free world, and we’re not going to have it,” said US Treasury Secretary Scott Bessent.

On Thursday, China said the US had “deliberately provoked unnecessary misunderstanding and panic” over the rare earths restrictions.

“Provided the export licence applications are compliant and intended for civilian use, they will be approved,” a commerce ministry spokesperson added.

This week, the world’s two biggest economies also imposed new port fees on each other’s ships.

The flare-up in the trade war brings to an end months of relative calm after top US and Chinese officials brokered a truce in May.

Later this month, Trump and China’s President Xi Jinping are expected to meet and experts have told the BBC the rare earths restrictions will give China the upper hand.

China’s new controls are bound to “shock the system” as they target vulnerabilities in American supply chains, said international business lecturer Naoise McDonagh from Australia’s Edith Cowan University.

“The timing has really upset the kind of timeline for negotiations that the Americans wanted,” he added.

Rare earth minerals are essential for the production of a whole range of technology such as solar panels, electric cars and military equipment.

For example, a single F-35 fighter jet is estimated to need more than 400kg (881.8lb) of rare earths for its stealth coatings, motors, radars and other components.

China’s rare earth exports also account for around 70% of the world’s supply of metals used for magnets in electric vehicle motors, said Natasha Jha Bhaskar from advisory firm the Newland Global Group.

Beijing has worked hard to gain its dominance of the global rare earth processing capacity, said critical minerals researcher Marina Zhang from the University of Technology Sydney.

The country has nurtured a vast talent pool in the field, while its research and development network is years ahead of its competitors, she added.

While the US and other countries are investing heavily to develop alternatives to China for supplies of rare earths, they are still some way from achieving that goal.

With its own large deposits of rare earths, Australia has been tipped as a potential challenger to China. But its production infrastructure is still underdeveloped, making processing relatively expensive, Ms Zhang said.

“Even if the US and all its allies make processing rare earths a national project, I would say that it will take at least five years to catch up with China.”

The new restrictions expand measures Beijing announced in April that caused a global supply crunch, before a series of deals with Europe and the US eased the shortages.

The latest official figures from China show that exports of the critical minerals were down in September by more than 30% compared to a year ago.

But analysts say China’s economy is unlikely to be hurt by the drop in exports.

Rare earths make up a very small part of China’s $18.7tn a year economy, said Prof Sophia Kalantzakos from New York University.

Some estimates put the value of the exports at less than 0.1% of China’s annual gross domestic product (GDP).

While rare earths’ economic value to China may be tiny their strategic value “is huge”, she said, as they give Beijing more leverage in talks with the US.

Despite accusing China of “betrayal”, Bessent has left the door open to negotiations.

“I believe China is open to discussion and I am optimistic this can be de-escalated,” he said.

During a meeting with the US private equity group Blackstone’s chief executive Stephen Schwarzman on Thursday, China’s Foreign Minister Wang Yi also highlighted the need for talks.

“The two sides should engage in effective communication, properly resolve differences and promote stable, healthy and sustainable development of China-US relations,” Wang said, according to the ministry’s website.

What China has done recently is “getting its ducks in a row” ahead of those trade talks with the US, said Prof Kalantzakos.

In curbing rare earth exports, Beijing has found its “best immediate lever” to pressure Washington for a favourable deal, Ms Bhaskar said.

Jiao Yang from Singapore Management University believes that although Beijing holds the cards in the short-run, Washington does have some strategic options at its disposal.

The US could offer to lower tariffs, which is likely to be attractive to Beijing as the trade war has hit its manufacturers hard, said Prof Jiao said.

China’s economy is reliant on the income from the goods it makes and exports. The latest official figures show its exports to the US were down by 27% compared to a year ago.

Washington can also threaten to hit China with more trade restrictions to hamper efforts to develop its technology sector, said Prof McDonagh.

For example, the White House has already targeted China’s need for high-end semiconductors by blocking its purchases of Nvidia’s most advanced chips.

But experts say that is likely to have only limited effects.

Measures targeting Beijing’s tech industry may slow China but won’t “stop it dead in the water,” said Prof McDonagh.

China has shown with its recent economic strategy that it is willing to take some pain to achieve its long-term goals, he added.

“China can carry on even if it costs a lot more under US export controls.

“But if China cuts off these rare earth supplies, that can actually stop everyone’s industry. That’s the big difference.”

When Kerry Dunstan and his partner set out to buy a new electric car this summer, one of the questions they asked was, “How’s the battery?”.

They’d found a 2021 Nissan Leaf with just 29,000 miles on it, and the dealer told them the condition of the battery, or its state of health (SOH), was still around 93%.

The couple were sold. For £12,500, they got an EV with a big boot and plenty of room for passengers.

Though Mr Dunstan, a cabinetmaker who also owns a somewhat snazzier electric Volvo SUV, hasn’t quite fallen in love with the aging Leaf.

“I like sporty, jazzy cars – and it’s just a bit ‘meh’,” he says.

However, he adds the Leaf has performed exactly as expected during the three months they’ve owned it.

It used to be that age and mileage were the two headline details pored over by would-be buyers of second-hand cars. But as more people shift to electric, scrutinising the health of a car’s battery has become arguably even more important.

How has that battery been treated? Did the last owner regularly fast charge it to 100%, for example? That has the potential to shorten an EV battery’s lifespan.

This battery black box problem has put some consumers off buying a second-hand EV. But battery analytics firms say they can reveal the condition of an old EV’s battery with high accuracy. And industry experts say some EVs are lasting longer than many predicted.

Take Mr Dunstan’s Nissan Leaf. This is a model of EV built without the kind of sophisticated, liquid-based battery cooling system common to many other EVs. While Nissan has rectified this in the latest generation of Leafs, earlier models show a considerable shortening of their range year by year, according to data analysed by US insurance and research firm NimbleFins.

Mr Dunstan is unfazed. “I charge both my EVs to 100% and I put them on charge when I need to charge them – I don’t worry about it,” he says.

For people in the market for a second-hand EV who are plagued by battery anxieties, however, Austria-based firm Aviloo says it has a solution. “We really can, completely independently, determine the state of health of a battery,” says chief product officer, Patrick Schabus.

Aviloo is one of several battery analytics businesses in the market. The company, which provides battery health certificates for major UK outlet British Car Auctions, offers two products.

There’s a premium test, where EV owners plug a data logging box roughly the size of a glasses case into their car so that it can monitor battery performance while they use the car over a few days, going from 100% charge down to 10%.

Or, they can opt for a quicker flash test, which uses a different box to suck up data from the car’s battery management software and then analyse it with the help of a computer model. “We can do this at a standstill in under two minutes,” says Mr Schabus.

The premium test observes battery discharge closely, picking up fluctuations in current or voltage, and can reveal extra detailed information about the health of individual cells in the battery, says Aviloo.

Marcus Berger, Aviloo’s chief executive, says his company’s analytics results sometimes diverge “substantially” from the battery SOH percentages produced by some cars’ own built-in analytics systems.

He challenges conventional wisdom that batteries with an SOH below 80% are too far gone: “An EV with a state of health below 80% can still be a great car… It just needs to be priced [appropriately].”

In New Zealand, EV owner Lucy Hawcroft, who works in a sustainability role for an infrastructure firm, bought a Nissan Leaf with her husband roughly three years ago. She recalls getting an SOH result of 95% or so from the dealership. But a year later an independent mechanic checked the SOH again for them.

“It dropped quite a bit,” she recalls. “My husband was a bit surprised, or concerned, about that.”

However, the car still has a range of around 160km (100 miles) when fully charged. The pair mostly use it for short journeys of up to 10km. Mrs Hawcroft says she has friends whose EVs have much bigger ranges, of around 400km: “That would be ideal.”

For David Smith, sales director at Cleevely Electric Vehicles in Cheltenham, being able to analyse used EVs’ batteries in detail is a deal-maker. Most customers ask for this information, he says. His company uses SOH reports from ClearWatt, another battery analytics firm.

“They’re completely independent. We can’t interfere with the reports,” he says. “Once customers have seen the report, that aids the sale nine times out of 10.”

Matt Cleevely, managing director at Cleevely Electric Vehicles, adds that it’s often possible to replace groups of cells or modules within a battery pack – far cheaper than installing a whole new battery.

As for how you should charge your own EV in order to best take care of its battery, Simona Onori at Stanford University says, “There is likely a sweet spot between frequent fast charging and avoiding it altogether.” However, she adds that, to her knowledge, this is not something that has yet been thoroughly studied.

Despite some consumers’ wariness, battery technology has noticeably improved in recent years, says Max Reid, head of battery costs at market research firm CRU. “The older batteries might last maybe 500 to 1,000 [charging] cycles,” he explains. “Now, it’s 10,000 cycles in some of these new EV cells coming out.”

Batteries that are no longer good enough for the EV they were designed for can still be useful, says Paul Chaundy at Second Life EV Batteries, in Dorset. For instance, some of his customers are businesses that use former EV batteries to store electricity at their premises. They might have, say, six electric forklifts but a grid connection only large enough for charging ports to supply two or three of the forklifts.

Regarding the varying methodologies car manufacturers use to generate SOH reports for their own vehicles, Mr Chaundy says, “We need more standards around that, I think.”