SEOUL - South Korean President Moon Jae-in has ordered an investigation into the unauthorized delivery of four THAAD anti-missile launchers in addition to two deployed by the United States military before his election, his spokesman said on Tuesday.

Yoon Young-chan, chief presidential press secretary, told a media briefing that Moon was "shocked" to hear that the additional launchers were brought in without being reported to the new government.

The presidential security adviser Chung Eui-yong reported to Moon that the launchers were secretly transported to the country. Moon ordered Chung and the senior presidential secretary for civil affairs to investigate secret delivery.

The security adviser is in charge of defense, security and foreign affairs. The civil affairs secretary is tasked with overseeing prosecutors, police and the intelligence agency.

About two weeks before the May 9 presidential election, two mobile launchers and radar for the US Terminal High Altitude Area Defense missile interception system were transported in the middle of night to a golf course at Soseong-ri village in Seongju county, North Gyeongsang province.

THAAD is composed of six mobile launchers, 48 interceptors, the AN/TPY-2 radar and the fire and control unit.

The clandestine transportation raised speculation that it was aimed to politicize security issues during the election campaign period, which tended to benefit conservative candidates in the past elections.

Moon spoke by phone with Defense Minister Han Min-koo, who was appointed by the ousted president Park Geun-hye, to verify the secret delivery in person, according to the presidential Blue House.

Defense Ministry spokesman Moon Sang-kyun told a regular press briefing earlier in the day that the status quo had been maintained regarding the THAAD battery deployment.

The state affairs planning advisory committee, which served as an actual transition committee for President Moon, held a reporting session with the Defense Ministry last Thursday.

During the session, the ministry did not report on the four launchers, the presidential press secretary said.

President Moon ordered the probe into how the launchers were delivered, who made the decision, why it was not made public and why it was not reported to the new government. He also ordered the investigation into whether the secret transportation was intended to avoid an environmental assessment on the THAAD deployment.

By law, no construction is allowed for a military base before the completion of the evaluation on whether it would have any environmental impact on people living around the base. Documents on the environmental assessment have yet to be submitted by the ministry.

Xinhua