The unprecedented ruling of the Republic of Korea's constitutional court on Friday 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 a US missile defense system tops the series of mistakes committed by Park during her four years in office. The move caused China-ROK relations to plummet to the lowest level since the establishment of diplomatic ties between them.

The ROK's retail giant Lotte Group agreed to a land swap deal with the government on Feb 28 paving the way for the deployment of the Terminal High Altitude Area Defense anti-missile system in the country. In fact, a part of the THAAD battery and other related equipment have already reached the ROK - on March 6, to be precise.

With the ROK 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, its ties with China have soured further. As China was forced to take necessary countermeasures, more and more consumers have shunned retail stores?operated by Lotte in China.

By jumping on the ROK government's bandwagon to help deploy THAAD, Lotte has crossed the bottom line of business operations and ethics. Therefore, it is only natural that its businesses in China have suffered a heavy blow.

Yet 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. One country's security apparatus should not 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 crisis.

The excuse used by the ROK to deploy THAAD does not hold water. Even ROK citizens know the US anti-missile system can only intensify tensions with the DPRK 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 neighbors. In fact, it could only break the established strategic equilibrium in the region.

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 a single or a few missiles as far as 3,000 kilometers away, George Nelson Lewis, a physicist and expert on missile defense at Cornell University's Judith Reppy Institute for Peace and Conflict Studies, was quoted last week 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. As such, the next ROK president will have to face other countries' backlash against Park's THAAD policy, which has already thwarted the healthy development of Beijing-Seoul ties.

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. The ousting of Park has created an opportunity to change the THAAD policy, and the next ROK president should seize this opportunity so that its ties with China can be repaired, because amiable Beijing-Seoul relations will benefit both countries.

The author is a senior writer with China Daily.

wanghui@chinadaily.com.cn