South Korean environmentalists held placards opposing the deployment of THAAD (Photo: VNA)

It is expected to take at least a year based on a similar evaluation for a THAAD deployment in Guam which had taken 23 months.

South Korean President Moon Jae-in ordered a proper environmental study of THAAD on Monday. The system has been subject to an informal environmental assessment afforded by what Seoul's presidential office Cheong Wa Dae has referred to as systematic efforts by the the defense ministry to make the THAAD battery appear smaller in size and scale.