South Korea's presidential office made it clear Tuesday that it has not received any formal briefing from the defense ministry on the presence of additional THAAD rocket launchers here.

The ministry said it has already briefed Cheong Wa Dae on the issue, responding to President Moon Jae-in's call for a probe into the matter related to the allies' missile defense system.

Moon said it's "very shocking" that the ministry had kept secret or did not announce the introduction of four more THAAD rocket launchers, according to his spokesman Yoon Young-chan. The equipment arrived in Korea apparently weeks or months ago.

A ministry official, however, said Wee Seung-ho, deputy minister for policy, briefed Moon's national security adviser Chung Eui-yong on pending defense issues last Friday.

"At that time, he reported the entry of four additional launchers (into South Korea)," the official said on the condition of anonymity, adding it reflects the ministry's official position.

Moon's office refuted the ministry's statement. 

There was no report on the extra THAAD launchers waiting to be installed at a former golf course in Seongju, North Gyeongsang Province, which has been chosen as the THAAD site, said Cheong Wa Dae.

One thing that seems certain is that Moon did not receive any briefing on the subject during his visit to the ministry a week after taking office. It's not clear whether he first raised the THAAD issue.

The State Affairs Planning Advisory Committee, a de-facto transition team for Moon, also said that it was told about only two THAAD launchers in operation, not about the other four, when receiving a briefing from the ministry.

The truth behind the dispute remains unconfirmed.

South Korean and US defense authorities have been reluctant to make public the specific process of deploying the highly strategic weapon.

In a statement issued on March 6, the US Forces Korea announced that the "first elements of the THAAD system arrived" in South Korea. THAAD stands for Terminal High Altitude Area Defense.

It was the only and last official confirmation on the delivery of THAAD components.

As two launchers were seen transported to the THAAD zone in late April, local media reported that four other launchers remain stored at nearby American military bases. The allies did not deny the news reports.

A THAAD battery requires at least six rocket launchers. 

The militaries of South Korea and the US were then quick in announcing that the THAAD system has reached its "initial operational capability" and it will be fully operational by the end of this year.

Moon, a liberal president, has maintained a negative view on what he says is a hasty deployment of THAAD in his country, a decision made by his predecessor Park Geun-hye to help counter North Korea's missile threats.

Moon said the administration should have gotten the National Assembly's approval based on public opinion, emphasizing the need for a transparent process. (Yonhap)