The agreement, which involves a land swap between Seoul and retail giant Lotte, was approved on Monday.
"We received a message that the board approved the exchange of land for THAAD (Terminal High Altitude Area Defense) deployment," the South Korean Defense Ministry said in a statement, as quoted by AFP.
That news was met with disapproval from China’s Foreign Ministry, with front man Geng Shuang claiming the system "severely disrupts regional strategic balance and jeopardizes the strategic security interests of regional countries including China."
Beijing "will definitely take necessary measures to safeguard its security interests," he said during a news briefing, adding that "all the consequences entailed will be borne by the US and the Republic of Korea."