All this has fed expectations that the two sides could soon make peace—or at least extend their truce. Mr Trump told reporters that he might let the deadline slide if a good deal is within reach. Another meeting between Mr Trump and Xi Jinping, China’s president, is under discussion. Investors have taken heart. American and Chinese stockmarkets have both risen by about 10% this year.
The outlines of a deal have been in view for a while. China would probably promise to buy lots of goods from America, from soyabeans to natural gas, and allow foreign companies more access to its economy. America would cut tariffs and perhaps promise to remain open to Chinese investors, as long as they are not part of a state-backed assault on sensitive technology.
Yet when negotiators get into the details, problems surface. After many frustrating years waiting for China to open its markets, the Americans suspect that its pledges will be empty. The Chinese suspect that America is motivated by a desire not for fair trade but for thwarting a new rival.
Two key outstanding questions are thus how to measure whether China lives up to its word, and what America can do if it fails. Scott Kennedy of the Centre for Strategic and International Studies in Washington says changes should be measured by China’s economic outcomes, not by its stated policies. The government has, for instance, agreed to scrap rules that foreign firms must find local partners to make cars in China. The test, says Mr Kennedy, ought to be whether foreign carmakers actually do set up wholly owned firms in China and operate them successfully.