Moon has ordered a probe at the defence ministry, saying it was "very shocking" the launchers had been brought in without being reported to the new government or to the public, presidential Blue House spokesman Yoon Young-chan said on Tuesday.
The Defence Ministry intentionally omitted details about the Terminal High Altitude Area Defence (THAAD) system battery (THAAD) in a report last week, when the new government was preparing for Moon's summit with U.S. President Donald Trump next month, Yoon told a briefing.
"The Blue House has confirmed that the Defence Ministry has intentionally dropped the introduction of four more launchers in its report," Yoon said.
Moon took office on May 10 without a transition period because a snap presidential election was held just two months after his predecessor, Park Geun-hye, was ousted in a corruption scandal. Moon inherited his defence minister along with the rest of his cabinet from the previous administration.
The THAAD battery was initially deployed in March in the southeastern region of Seongju with just two of its maximum load of six launchers to counter a growing North Korean missile threat.
An earlier version of the defence ministry report specified the total number of launchers being prepared for deployment and the name of the U.S. military base where the four were being kept, but the reference was removed in the final version delivered to the Blue House, Yoon said.
The Pentagon said it had been "very transparent" with South Korea's government about THAAD deployment.
US MISSILE DEFENCE TEST
During his successful presidential campaign, Moon called for a parliamentary review of the THAAD system, the deployment of which has infuriated China, North Korea's lone major ally. Moon had also called for more engagement and dialogue with Pyongyang.
In Washington, the U.S. military said on Tuesday it had staged a successful, first-ever missile defence test involving a simulated attack by an intercontinental ballistic missile.
"The intercept of a complex, threat-representative ICBM target is an incredible accomplishment ... a critical milestone for this program," Vice Admiral Jim Syring, the director of the Missile Defence Agency, said in a statement.
Moon's order of a probe over the THAAD deployment came amid signs of easing tensions between South Korea and China, a major trading partner.
China had been incensed over the THAAD deployment, saying it would do little to deter the missile threat from North Korea while allowing the U.S. military to use its radar to look deep into its territory and at its own missile systems.
Beijing is also troubled by the possibility the THAAD system would open the door to a wider deployment the U.S. missile defence systems, possibly in Japan and elsewhere, military analysts say.
South Korean companies have faced product boycotts and bans on Chinese tourists visiting South Korea, although China has denied discriminating against them.
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