Cheong Wa Dae effectively ordered the Ministry of National Defense on Wednesday to reassess the environmental impact of the deployment of a US anti-missile system on its site.

However, it excluded from the reassessment the two launchers and radar of the Terminal High Altitude Area Defense that had already been installed.

The presidential office also said whether to deploy additional four launchers would be determined after the completion of the environmental impact assessment.

Cheong Wa Dae doubts the ministry conducted a summary assessment to speed the deployment by assessing the environmental impact on the initially provided area of the site. The presidential office said the whole area should have undergone an environmental impact assessment, hence a full-blown assessment will start.

The assessment requires public participation and usually takes more than a year.

It will buy President Moon Jae-in time to try the “diplomatic card” he vowed to use during his campaign. There is speculation he may seek Beijing’s understanding while attempting to give momentum to inter-Korean relations.

But his strategic ambiguity on the THAAD issue is like walking a tightrope. It appears risky to maintain the balancing act for long. The assessment period should be minimized. A prolonged uncertainty is likely to send the wrong signals to the US and China.

Though Washington has said it fully understands Seoul’s position, foot-dragging on the assessment will be of little use to either side. Right now, Washington is saying it trusts Seoul, but the trust may sour if Seoul strains the alliance.

Following news on the decision to suspend the deployment of additional launchers, the Global Times, an English-language sister newspaper of the People’s Daily, the official news outlet of the Chinese Communist Party, said in an editorial that the pressure on Seoul has taken effect, shaking its will. A protracted assessment will give the impression that South Korea may eventually cancel the THAAD deployment.

A signal to avoid sending is that Moon thinks South Korea has a better chance of working with China to contain North Korea than working with the US, as US Senate Minority Whip Dick Durban told the Washington Examiner.

A worrisome scenario is that the assessment will cause division at home.

The full-fledged assessment entails public participation. If residents want, the Defense Ministry should hold hearings or briefings.

Naturally, it should collect comments from residents living in an area near a proposed military establishment. The problem is a public hearing may turn into a battleground for pro-THAAD and anti-THAAD groups. Not only anti-THAAD residents, but their sympathizers living away from the site may stage joint violent protests during the hearing, disrupting and delaying the assessment process.

If a major negative impact is found, public sentiment could suddenly turn around.

North Korea launched a salvo of anti-ship cruise missiles Thursday, while the installation of additional launchers is suspended. It was the communist state’s fifth missile provocation after Moon took office one month ago. It has been seen as a message that Pyongyang would not be pressured into abandoning its nuclear and missile programs.

Given the higher frequency of the North’s missile tests in recent months, the complete deployment of the system is urgent. Anti-missile capability has become a matter of survival for the South.

Suspending the launcher installation for long is risky as the North has been stepping up missile provocations. The assessment should end as soon as possible to fill the void in the missile shield.

The Moon administration should stick to its official position that the THAAD deployment is an irreversible alliance decision.

The assessment authorities should be meticulous about gathering comments from residents to prevent public hearings from becoming a fighting arena of political ideologies.

The Moon administration needs to manage international relations wisely, keeping its stance that the Korea-US alliance is the foundation of the national security. It should avoid creating a situation where the issue of installing additional launchers will shake the basis of the alliance.