Many people have taken the news on Friday that the United States and China have agreed to set up economic and financial working teams as a sign the two countries have moved past the incident of the "spy balloon" — which the US side has since admitted was not spying at all — to focus on repairing bilateral ties. Yet, just one day later, it was reported that the Joe Biden administration is mulling a huge arms sale to Vietnam.

The deal, which includes F-16 fighter jets as well as other advanced weapons, is supposedly to help Hanoi markedly enhance its ability to defend Vietnam's "sovereignty and territorial integrity" in the South China Sea, according to the Biden administration.

The move is a threat to regional peace and stability, and unmistakably intended to be a provocation to China. The arms deal clearly indicates the Biden administration does not want the maritime dispute between China and Vietnam to be settled through peaceful negotiations and dialogue, something the two neighbors have been engaged in for a long time.

The US' military assistance to the Philippines is of the same kind and with the same aim. For China and its neighbors, the disputes are reasons for talks and for cooperation to help build trust. But Washington regards the disputes as crevices into which it can drive wedges to alienate China from countries in the region.

After repeated stress tests on its economy from its efforts to decouple the US economy from China's, the Biden administration seems to realize that the US has no choice but to learn to co-exist with the world's second-largest economy. Jose Fernandez, the US under-secretary for economic growth and the environment, told a briefing in New York on Friday, the US won't be able to cut China out of the critical minerals supply chain, saying "We are perfectly happy to work with them on this and right now we purchase many of the minerals from Chinese companies."

But the weapons deal is a reminder to those feeling positive about the easing of their ties that, even though the two sides appear to have reached a tacit understanding on the necessity for co-existence, their relations are still strained.

Beijing is well aware of the double-faced nature of the US' China policy that is determined by the complexity of the Sino-US ties as well as the partisan divide in Washington. So while the two sides are also likely to build similar working teams on trade and climate change, the US' military and security policies and diplomatic offensive targeting China will continue to fuel tensions. In other words, although neither country can afford to be without each other, for the time being at least, what defines their ties continues to be frictions.

In a nutshell, the formation of various kinds of working teams, not to mention the resumption of suspended communication mechanisms, does not signal an overall improvement of Sino-US ties. As both sides are holding a wait-and-see attitude, their relations will continue to be defined by tensions, uncertainties and mistrust.