The extending of the talks between China and the United States to resolve their trade and economic frictions will hopefully give substance to the optimism expressed by both sides that they can reach a deal.

US President Donald Trump, senior US officials, and Vice-Premier Liu He, the special envoy of President Xi Jinping, who is heading the Chinese delegation, all expressed the belief on Friday that the two sides have made significant progress toward reaching a comprehensive agreement that will put an end to the current trade standoff.

It is to be expected that the discussions at this stage will be the toughest test yet for the two teams of negotiators, and their task is not one to be envied. However, the unscheduled two-day extension to their discussions indicates that tangible headway is being made in their joint efforts to find a mutually acceptable way to resolve their differences and put an end to their quarrel.

Given what was said on Friday, it seems the talks have gone more deeply and extensively into the bilateral relationship than either side initially anticipated. As US President Donald Trump observed, "we're covering things that we didn't even know we'd be covering."

So the fact that the to-and-fro is still in progress this far down the line highlight that there is a shared desire to secure an accord that delivers on the rapport that has been established — also perhaps beyond both side's expectations.

But it would be getting ahead of the situation to consider the final push toward a consensus on principled, mutually beneficial cooperation all done and dusted. That consensus, which President Xi identified as the objective of the talks when he met with the US negotiators after the previous round of negotiations in Beijing, has still not been completed, and probably will not be until the two leaders meet to agree on the final details. But there is no doubt that both sides are aware of how momentous such a consensus would be, beyond the tangible rewards it would offer both countries. For if the two sides can iron out their core differences by abiding by the principles of mutual respect and mutual benefit, it would reset their relationship in a way that would bode well for the future.

History in the past four decades shows that the two countries benefit in an all-around way from harmonious trade and economic relations, as they provide the ballast for their relationship.

There is obviously still more work to be done. However, if neither side puts a foot wrong, a deal will finally be signed sooner or later.