Currently, two launchers and a radar of the THAAD system is deployed and in operation in Southeastern, South Korea. The system typically requires a total of six launchers, however, the installment of remaining four launchers, which are currently in South Korea, has been halted. 

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The decision is made by President Moon who ordered an investigation after he claimed that his office was not briefed about the arrival of the four new launchers. He also demanded a full environmental impact assessment of the deployment site, which can take up to weeks or even months to complete. 

The United States expressed frustration on the decision by President Moon. Ed Royce, the chairman of House Foreign Affairs Committee, addressed the issue on Wednesday night, and stated, "I hope any environmental concerns related to the full deployment of THAAD will be dispelled with a quick and thorough review. We need to use every tool at our disposal - including additional sanctions - to address the Kim regime's threats."