O VER THE past two years investors and executives watching the trade tensions between America and China have veered between panic and nonchalance. Hopes for a cathartic deal that would settle the countries’ differences have helped global stockmarkets rise by a bumper 13% this year. But on May 5th that confidence was detonated by a renewed threat by President Donald Trump to impose more tariffs on Chinese imports. As The Economist went to press negotiations rumbled on, but no one should be under any illusions. Even if a provisional agreement is eventually struck, the deep differences in the two countries’ economic models mean their trading relations will be unstable for years to come.

Some trade spats are settled by landmark agreements. In the 1980s tensions between Japan and America were resolved by the Plaza Accord. In September Mr Trump agreed to replace NAFTA , which governs America’s trade with Canada and Mexico, with a renamed but otherwise rather similar accord (although the new treaty has yet to be ratified by Congress). Even by those standards the China talks have been an epic undertaking involving armies of negotiators shuttling between Beijing and Washington, DC , for months on end. Yet they have never looked capable of producing the decisive change in China’s economic model that many in Washington crave.

There is some common ground (see Finance section). China is happy to buy more American goods, including soyabeans and shale gas, in an effort to cut the bilateral trade deficit, a goal which is economically pointless but close to Mr Trump’s heart. It is willing to relax rules that prevent American firms from controlling their operations in China and to crack down on Chinese firms’ rampant theft of intellectual property. Any deal will also include promises to limit the government’s role in the economy.