Secretary of State Rex Tillerson holds a press briefing during the UN General Assembly in New York, US, Sept 20, 2017. [Photo/Agencies]

Symbolism matters on diplomatic occasions, and it will during the planned visit of US President Donald Trump to China later this year. Plenty of thought is no doubt being devoted to it, and plenty of endeavors will be underway to make sure his visit is successful, even fruitful.

However, US Secretary of State Rex Tillerson's ongoing trip to Beijing must be anything but symbolic.

Rather than being a routine show of mutual goodwill to set the stage for Trump's visit, the guest and his hosts must avail themselves of their meetings to engage in candid communication to straighten at least one thing out－what each can expect from the other to ensure the situation on the Korean Peninsula does not deteriorate and spiral out of control.

Of course trade is important. It may actually be the foremost topic addressed during the meetings, particularly as fear of a potential trade war looms large on both sides of the Pacific. Mutual assurances are indispensable for averting that scenario.

But as long as both parties make room for some give-and-take on trade issues, Tillerson's talks will be of more immediate portent if they can take some of the heat out of the peninsula's inflammable nuclear crisis.

Both Trump and Democratic People's Republic of Korea leader Kim Jong-un appear jumpy these days. And the rest of the world seems to have grown increasingly blasé about this of late, even as the two leaders exchange vows of mutual destruction, few seem ready to believe their words should be taken seriously.

Perhaps; but that does not mean nothing will happen. The escalating exchanges of threats and insults pose an ever growing risk and they increase the chances of a costly miscalculation. That Pyongyang just took Trump's most recent threat to eliminate it as "declaration of war" may well show its existential concerns: It is unlikely it will make good on its threat to shoot down US bombers flying in international airspace, unless they threaten its survival.

Reason dictates that despite all the saber-rattling and verbal abuse, every party is well aware that war has to be avoided as the costs would be too great to bear.

The latest UN sanctions need time to begin to bite. On Thursday, China announced it has ordered DPRK enterprises operating on its soil to close within 120 days.

But to ensure that the worst-case outcome does not materialize, while further coordinating their stances on the implementation of the UN sanctions to make sure they work, Beijing and Washington also need to discuss what else they can do to resolve the peninsula crisis peacefully.