Relations between South Korea and China are at rock bottom. You need look no further than what happened in Beijing and Seoul this week as the two countries marked the 25th anniversary of diplomatic ties.

Commemorative events held for the silver anniversary in the two capitals were anything but as glittering as they should have been. There was no joint ceremony, unlike in 2012 when the 20th anniversary celebrations drew senior officials including Xi Jinping, who was then the vice president.

This year, no minister or higher-level official attended anniversary events held in Seoul and Beijing. President Moon Jae-in and Xi -- and their foreign ministers, too -- exchanged congratulatory messages. But Xi even indirectly touched on the row over the Terminal High Altitude Area Defense system in the message.

Due to China’s retaliation against the decision to deploy the US missile shield system in South Korea, a chill has been prevalent between the two countries in the months leading up to the anniversary.

China’s restrictions on travel to Korea resulted in a sharp drop in the number of Chinese visitors to Korea -- and to a lesser degree Korean visitors to China too -- and Chinese authorities’ well-orchestrated, harsh discriminative punishments against Korean firms like Lotte and Hyundai Motor have hit Korean industry hard.

The retaliatory measures are hard to accept. First of all, the THAAD battery does not target China, for which it needs a more powerful, longer-range radar. The Chinese actions also go against the guiding principle that the two countries should separate politics from other areas of their bilateral relations. Besides, what Chinese authorities have taken per se do not fit into the image of a country striving to gain respect as a global superpower.

In any case, the cold reality shows that the cooperation the two countries have built up over the past quarter of a century could be in danger of being wiped out with a single stroke. It is truly regrettable and painful, especially if one looks back on what they have achieved so far.

Since the former Korean War adversaries forged official ties in the wake of a thaw in the Cold War, their bilateral relations expanded by leaps and bounds. Economic cooperation stood out, with bilateral trade surging 33-fold as China benefited from Korean industrial technology and capital at a time when it was being catapulted into the world economy and Korea too benefited from advancing to one of the world’s fastest-growing markets.

Human exchanges had expanded remarkably as well. Before the THAAD row erupted, the number of people visiting each other’s country reached 11 million. There are about 60,000 Korean students studying in China and an almost equal number of Chinese students are staying in South Korea. It would be no exaggeration to say the two countries cannot now live well without each other.

The biggest problem is that the row over THAAD is not easy to solve. Xi has already said that the THAAD issue is one of China’s “core interests.” Chinese officials say the THAAD radar is intended to spy on China, but one knows that it is nothing but a pretext to check US military might in the region and challenge American global hegemony.

For their part, South Korea and the US cannot back off from the deployment of the THAAD battery unless the North does away with its nuclear and missile threats.

The best solution could be China pressuring or persuading North Korea to abandon its nuclear bombs and missiles. Then South Korea and the US would have no reason to stick to the missile interceptor system.

For China, what’s at stake is not only its relations with South Korea but also its reputation as a responsible leader of the international community. Remember China already has a long list of issues – like border disputes with India and territorial disputes with Japan and other Asian countries – which makes the world suspect its rise. China cannot change such a negative perception unless it changes itself.