Cheong Wa Dae said Wednesday the Defense Ministry had deliberately not reported the arrival of four launchers for a US anti-missile system. It came a day after the presidential office made public the ministry’s omission of the information in a briefing and President Moon Jae-in’s order to investigate.

According to Cheong Wa Dae, the related content was written on the draft of the report, but deleted in the final report made to Chung Eui-yong, chief of the National Security Office. Cheong Wa Dae also disclosed that Chung asked Defense Minister Han Min-koo later if he knew the four launchers were already in Korea and that Han answered, “Is there really such a thing?” Han denied he had ordered the omission in the briefing, saying “there could be differences in nuance when people talk.”

Deliberate omission in a military briefing is a serious matter, but Cheong Wa Dae needs to rethink if the revelation of the omission serves national interest. It would be to investigate the incident calmly and reprimand those responsible according to the investigation results. There are criticisms that making a fuss about a defensive weapon under the rising North Korean nuclear and missile threat is not desirable.

The disclosure of the omission and the order of investigation came out of the blue. Experts or those interested in the system would be well aware that a Terminal High Altitude Area Defense battery consists of at least six launch vehicles, operations centers and radar. As everyone knows, two of the six launchers were already deployed in Seongju, North Gyeongsang Province, in April. It is easily expected that four more launchers should be installed to complete the battery. News media reported the four launchers were spotted being transported along a local expressway to a US base in Korea. The ministry said that it would not confirm their existence, movement and deployment schedule, citing security reasons.

Then, Moon said the omission of the four launchers in the briefing was “very shocking.” If he had been really unaware of the existence of the four launchers in Korea, that would be a problem in itself. THAAD was one of the most contentious issues for presidential candidates, including Moon, and its deployment in Korea was discussed many times during their debates.

If he first knew about the four launchers Tuesday or if he intended to prevent the arrival of additional launchers, he might well have been shocked. But he needs to calm down and ponder whether he made a mountain out of a molehill.

The revelation of the omission was so sudden and unexpected that opposition parties suspected it might be an attempt to create anti-THAAD national sentiment or to divert attention from Moon’s controversial nominations.

Considering the launchers were brought in by the US to protect its bases in Korea and that China expects the new South Korean administration to move to get THAAD out of the Korean Peninsula, Cheong Wa Dae should not have rattled on about the omission incident and the order of investigation.

The Chinese Foreign Ministry expressed concern Wednesday about the Defense Ministry not reporting the four launchers to Cheong Wa Dae and repeated its call for the withdrawal of the system.

The US Defense Department said Tuesday it had been “very transparent” in its deployment of the THAAD system in South Korea.

It is questionable if the revelation was needed ahead of a Korea-US summit expected to be held this month.

North Korea has fired nine missiles this year, including three after Moon took office. It is expected to deploy some of those missiles soon. THAAD is a weapon to intercept North Korean missiles. The US regards the system as a cornerstone of its alliance with South Korea.

Wrongdoings within the military should be corrected, but investigation should not lead to questioning the rationale of the system or the alliance with the US.

The THAAD issue should be treated calmly and prudently in view of the national interest.