SEOUL, Oct. 31 (Xinhua) -- South Korea's defense ministry on Monday denied a claim by an opposition lawmaker that a behind-the-scene heavyweight may have intervened in the July decision between Seoul and Washington to deploy a U.S. missile shield system on South Korean soil.

Defense Ministry spokesman Moon Sang-kyun told a routine press briefing that it would never be true after being asked about Rep. Kim Jong-dae's claim that a political big shot behind the curtain may have meddled in the deployment decision of Terminal High Altitude Area Defense (THAAD).

Kim, a lawmaker of the minor Justice Party, said in his Facebook page on Thursday that the THAAD deployment decision was made in July and that rumors were rife about the attempt of Lockheed Martin, the THAAD manufacturer, to contact heavyweights of the Park Geun-hye government.

The opposition lawmaker said the behind-the-curtain figure pulling the strings favorable to Lockheed Martin must be found.

Kim didn't refer to Choi Soon-sil, a longtime confidante of President Park Geun-hye, who has been suspected of having interfered with state affairs, including the editing of presidential speeches and the accessing of presidential reports on diplomatic and defense affairs.

Reversing an earlier stance of so-called "Three Nos," South Korea abruptly announced a joint decision with the United States on July 8 to install one THAAD battery in southeastern South Korea by the end of next year. Three Nos mean no proposal, no consultation and no decision on THAAD deployment.

Denying the suspected intervention, the defense ministry spokesman said the THAAD deployment decision was announced after going through legitimate consultation procedures.