The unprecedented ruling of the constitutional court of the Republic of Korea (ROK) on March 10 made Park Geun Hye the first president to be removed from office after impeachment.

The ROK has to complete a presidential by-election within 60 days, and the next president faces the formidable task of righting the wrongs of the Park administration.

From a geopolitical perspective, the decision to deploy an advanced US missile defence system tops the series of mistakes committed by Park during her four years in office.

The move caused the relationship between Beijing and Seoul to plummet to its lowest level since the establishment of diplomatic ties in 1992.

On February 28, the ROK’s retail giant Lotte Group agreed to a land swap deal with the government, paving the way for the deployment of the Terminal High Altitude Area Defense (THAAD) anti-missile system in the country.

In fact, a part of the THAAD battery and other related equipment have already reached the country – on March 6, to be precise.

With Seoul expediting the process of deploying the US missile shield under the pretext of guarding against the military threat from the Democratic People’s Republic of Korea (DPRK), its ties with Beijing have soured further.

As China was forced to take necessary counter measures, more and more Chinese consumers have shunned retail stores operated by Lotte on the Chinese mainland as well as the company’s duty-free shops in the ROK.

Chinese have also cancelled tourist trips to the neighbouring country, and Korean celebrities found their concerts and television appearances in China cancelled one after another. However, Chinese officials publicly denied a ban on the entertainers was in place.

The tense atmosphere between the two countries is now being felt even in some remote areas in China, while ROK officials talked about taking countermeasures to China’s countermeasures.

To the Chinese, the antiROK sentiment is justified. Take Lotte’s dilemma in China as an example. By jumping on the government’s bandwagon to help deploy THAAD, Lotte is seen to have crossed the bottom line of business operations and ethics.

It has acquired the hallmark of a company out to harm another country’s security interest. Therefore, it is only natural that its businesses in China have been dealt a heavy blow.

Worse, the severe consequences of THAAD’s deployment go far beyond the economic and trade fields, for it poses a threat to the security of countries in the region, including China.

Some in the ROK deem the introduction of THAAD an internal affair, to which China cannot possibly agree.

One country’s security apparatus should never threaten, let alone sabotage, those of other countries. This is the overriding principle defining international relations. And history warns us that even one misstep in this regard could push friendly countries to the brink of war.

The excuse used by the ROK and the United States to deploy THAAD does not hold water either. Even ROK citizens know the US anti-missile system can only intensify tensions with their neighbour in the north and thus make the country more insecure.

The developments on the Korean Peninsula in recent months show that responding to an arms threat with a counter-threat will not ease the long-standing hostility between the two neighbours. It also generates more reasons for the DPRK to continue its nuclear ambitions and missile program.

Although both Washington and Seoul refuse to concede that the deployment of THAAD poses a severe threat to China’s security interests, there is no denying that it could be used to spy on Chinese territory.

The anti-missile system can detect the launch of missiles as far as 3,000 kilometers away, George Nelson Lewis, a physicist and expert on missile defence at Cornell University in New York, was quoted on March 9 by the London-based Financial Times as saying.

If that were even half true, it would mean a large part of Chinese territory would be under THAAD’s surveillance. No country will tolerate such an act of blatant infringement on its national security.

More seriously, many in China believe the US anti-missile system, as part of the ‘pivot’ to Asia policy implemented by the previous US administration, serves as the US strategic hedging against China.

In response to potential missile threats from the DPRK, Japan has also openly showed its interests in introducing the THAAD system. In recent years, the US has strengthened its military alliances in the Asia Pacific in an apparent move to counter China’s rise. No doubt, its military alliance with the ROK and Japan has assumed a rising importance in implementing its regional strategy. By placing the anti-missile system in China’s neighborhood, Washington can fill the missing link of its global missile defense system and contribute to its strategic maneuvering in the Asia Pacific as well. But its regional allies will have to face the backlash and even take the risks. Seoul's icy-cold relationship with Beijing is a case in point. Thanks to efforts by both neighbours, China has become the ROK’s largest trading partner, the largest destination of its overseas investment and its largest source of overseas students. At the same time, the country is one of China’s most important partners in investment and trade and people-topeople exchanges.

The current difficulty in bilateral ties has been the result of the ROK’s cooperation with the US in deploying the missile defense system on its soil in disregard of China’s rightful concerns and legitimate interests. Beijing has repeatedly demanded Seoul value bilateral ties, take anti-THAAD voices from people on both sides seriously and stop the process of deployment.

The ball is now in the ROK’s court. Given that a political transition could naturally lead to major policy changes, the ouster of Park has created an opportunity to change the THAAD policy. The next ROK president should seize this opportunity so that ties with China can be repaired, because amiable Beijing-Seoul relations will benefit both countries.

A sensible approach for Seoul would be to mitigate the THAAD security threat to China by canceling the wrong decision or at least postponing its deployment permanently.

As China’s Foreign Minister Wang Yi has put it, the stubborn deployment of the THAAD system by the US and the ROK is now the biggest issue affecting Beijing-Seoul ties.

China strongly advised the ROK to halt the deployment and not stray further down the wrong path, otherwise it will only end up hurting itself and others, Wang warned.

The ROK presidential election is due to be held on May 9. Moon Jae-in, the liberal politician tipped to become the next president, is a well-known advocate of a “sunshine policy” of engagement with the DPRK. He has said that if elected, he would review how the government would deploy the US missile defence system and would consult China.

As the presidential election unfolds, the outside world will have a clearer idea about the policy orientation of the ROK’s next leader. For whoever wins the election, how to improve ties with Beijing will be a major challenge ahead.

It is hoped he or she will come up with a solution that could address the concerns of both countries through peaceful negotiations.

After all, the relationship between China and the ROK has bilateral and regional significance because both play an important role in stabilising the situation on the Korean Peninsula as well as in East Asia cooperation and development.

The writer is Senior Editorial Writer, China Daily (Asia), Hong Kong. This is a series of columns on global affairs written by top editors and columnists from members of the Asia News Network and published in newspapers and websites across the region.