As the trade negotiators of China and the United States gather in Shanghai on Tuesday and Wednesday to resume their talks aimed at ending the ongoing tariff war the mood surrounding them is palpably more subdued than it was ahead of the previous round of talks in May.

Patience is needed because the shortening odds that they would be able to navigate their way to a deal last time around were dashed on the wrecking reefs of seeming intransigent differences on a number of key issues, and the subsequent rhetoric from both sides that they are willing to out-wait the other.

That the two sides have returned to the negotiating table is a positive sign that they still want to strike a deal. After all, they both know neither will be the winner in a full-blown trade war. Recognizing that fact, they should demonstrate a shared willingness to find, if not a clean-sweep solution, at least a way out of the current deadlock.

Their one-year trade quarrel has already inflicted wounds on businesses of both sides, not to mention the harm it has done to the global economy. The International Monetary Fund warned last month that current and threatened US-China tariffs could slash global economic output by 0.5 percent in 2020, not a pleasant thought, especially when uncertainties from other directions such as Brexit are added to the mix.

China has already demonstrated it is going to engage in the talks with sincerity. As a sign of goodwill, it announced purchases of more US agricultural products on Sunday, including soybeans, cotton and pork. Something that will have pleased US farmers. The US should reciprocate if it wants any progress to be made.

China insists on equality and respect as a basis for reaching any possible deal, and the US should give its go-to tactic of maximum pressure a couple of days off as it has proven ineffective against China.

It may be just a coincidence that this round of talks is being held in Shanghai, where 47 years ago, the two sides signed the Shanghai Communiqué that laid the foundation for the normalization of bilateral relations. But it is certainly an auspicious venue.

The differences that existed then between the two countries after decades of estrangement were definitely much greater than they are today. Yet by keeping the big picture of Sino-US relations in mind, and by agreeing to disagree, negotiators still managed to reach a deal that served both countries' interests over the 40 years to come by focusing on their common ground.

Hopefully, the wisdom of the older generation will guide the two sides' discussions this time around.