The timing could not be better. On 1 September 1939, German troops crossed the border into Poland, triggering the start of the second world war. Eighty years to the day later, on 1 September 2019, Donald Trump plans to impose a 10% tariff on a fresh range of Chinese imports into the US. If that happens, it will mark the moment when trade’s cold war turns hot.

Make no mistake, the unexpected announcement threatens to have serious consequences. Up until now, the Chinese goods targeted for tariffs have been carefully selected to avoid hurting consumers. That is no longer the case. From next month, almost everything China sends to the US will be affected. In bald terms, that means Americans are going to be paying more for their smartphones, laptops and clothes. Trump boasts that the US is going to be “taxing the hell out of China” but he has got the economics completely wrong. The taxes will be paid by Americans faced with paying more for imports.

With less than 18 months to go before the culmination of the 2020 presidential election race, this is a strategy fraught with risk. Trump is gambling that China’s leader, Xi Jinping, will bow to the pressure and sign a comprehensive trade deal that would provide greater market access for American companies, increase imports of US agricultural products and act to prevent the theft of American intellectual property.

The US president is also using the threat of a full-blown protectionist standoff between the world’s two biggest economies to bully the Federal Reserve, America’s central bank, into further cuts in interest rates. Global tensions were top of the Fed’s list of concerns when it announced a quarter-point cut in official borrowing costs last week. Those tensions have just got a whole lot worse.

China is waiting to see whether someone with less protectionist instincts wins the race for the White House next year

Trump also thinks that he will be able to squeeze more trade concessions out of the European Union if he can bring China to heel. Germany – particularly its car industry – has been served notice by the president that it is next.

But the strategy relies on Beijing buckling, something that it has yet to do. China’s initial response to Trump’s announcement – that this is not the way to negotiate – signals that Xi is prepared to play the long game. To be sure, tariffs are hurting the Chinese economy, which is growing at its slowest pace since the early 1990s. But China is still expanding by just over 6% a year, three times as fast as the US.

What’s more, global financial markets were caught completely unawares by Trump’s latest salvo and there was a predictable response to his tweets: tumbling share prices, cheaper oil and a flight into safe havens such as gold.

Xi thinks that turmoil on Wall Street is not necessarily what the president wants in the coming months. China is also waiting to see whether someone with less protectionist instincts wins the race for the White House next year, and whether Republicans shaping up for tight congressional races in 2020 will start putting pressure on Trump to be conciliatory if the US economy starts to slow under the weight of the trade war.

But China will do more than sit back and wait for Trump to reconsider. It has weapons of its own and will announce retaliation: by banning certain US companies from doing business, by limiting the exports of rare earth materials that are crucial for hi-tech US companies, and by raising tariffs on American goods.

How will Trump respond to that? Not by folding, that’s for sure. And that leaves the global economy balanced on a knife edge.

BA’s pilots will be aware that Willie Walsh is not one to shy away from a confrontation. Photograph: Andy Rain/EPA

BA pilots should be wary of Willie’s warm words

No adjective appears next to Willie Walsh’s name more often than “pugnacious”. The former pilot, who runs British Airways’ parent company, IAG, rarely shies away from confrontation and usually leaves his opponent nursing a bad headache. Just ask Richard Branson, who once offered him a £1m wager over the future of Virgin Atlantic, only for Walsh to suggest that the stakes be changed to a “kick in the groin”.

The Irishman is rather more conciliatory in the tone he takes with pilots, having served 18 years in the cockpit at Aer Lingus.

With BA facing the prospect of summer strikes by pilots, Walsh spoke of his “huge respect” for the professionalism of his aviators. But he has form for ruthless strikebreaking, both at BA and Aer Lingus, and his underlying message was no less robust for its scrupulous politeness.

He was not involved in pay negotiations, he said, but knew what it was like to sit on both sides of the table.

He claimed he would not have made such a generous offer as a manager (BA has suggested an 11.5% rise over three years), and that, in his days as a union representative, he would have grabbed it and run. When Walsh deploys that kind of rhetoric, it usually indicates that his resolve has hardened.

BA has plenty to lose here, given that strike action could cost it £40m a day. But if summer holidays are disrupted, the carrier may not struggle to make public villains out of the pilots, who tend to earn significantly more than many of their passengers.

BA will also point out that the Unite and GMB unions, which represent less well-paid staff such as cabin crew, have already accepted the airline’s pay offer.

Conciliation talks are continuing, but pilots will know that they are up against a battle-hardened opponent.

Rocket fuel? Greggs’s vegan sausage roll. Photograph: Amy Fortune/Alamy Stock Photo

Vegan success shows Greggs can roll with a changing market

The vegan sausage roll has acted as rocket booster for Greggs, helping propel it towards a very modern form of retail success as it reaches new customers.

The news that the Newcastle-based company now sells more takeaway coffee in the UK than Starbucks, while only Tesco sells more sandwiches and McDonald’s more breakfasts, is astounding. Hold the McMuffin.

Shareholders are getting a Quorn-and-pastry-funded £35m special dividend, after sales at established stores leapt 10.5% and profits jumped more than 50% to £40.6m in the six months to 29 June. While others are closing shops, Greggs is on track to open its 2,000th outlet in the next few weeks as part of plans for 100 new sites this year.

Six years ago it was another story: the company put a freeze on expansion after a string of profit warnings prompted by falling sales. It seemed customers had tired of lukewarm sausage rolls and tatty stores. An attempt at reinvention with the Greggs Moment coffee shop was a flop, and the company was making more excuses than it was snacks.

But since Roger Whiteside was appointed chief executive in 2013, the chain’s fortunes have been transformed. It’s amazing what careful consideration of the changing desires and behaviour of your customers can do for business.

Bringing Greggs up to date with modern food trends – with porridge for breakfast, fresh salad for lunch and actually decent, ethically sourced coffee, as well as the vegan sausage roll – has brought in punters who never bothered before. Clever use of social media – capitalising on Piers Morgan’s outrage over the meatless savoury snack, for example – has also updated the bakery’s image.

The company’s success on the high street is a prescient lesson for so many retailers who are retreating from stores. If you create something desirable and work out how to communicate with potential customers in a creative modern way, perhaps you too could get on a roll.