But despite local fears, radiation levels were 0.01659W/㎡, 0.004136W/㎡, and 0.000886W/㎡ at 100 m, 500 m, and 700 m from the radar. That is a mere 0.009 to 0.166 percent of the permissible standard 10 W/㎡ and lower than the radiation from a cellphone searching for a mobile relay station, a Defense Ministry spokesman said.

Officials from the two ministries went to the site in Seongju, North Gyeongsang Province by helicopter to avoid a clash with angry protesters who are blocking the road.

Based on the results, the Environment Ministry plans to provisionally conclude the environmental assessment within this month. That would clear the way for the U.S. to set up the remaining four launchers that have sat in storage so far pending a review, a plan already approved by President Moon Jae-in after North Korea's latest missile test.

Electromagnetic radiation from the Terminal High-Altitude Area Defense battery stationed in southwestern Korea is virtually zero and has no harmful effect on people, tests by the environment and defense ministries show.

Noise levels including an emergency generator for the powerful X-band radar were 51.9 ㏈, 50.3 ㏈, and 47.1 ㏈ at 100 m, 500 m, and 700m from the radar. The standard daytime noise level in residential areas is 50 dB. The spokesman said, "There is almost zero effect of noise on local residents since the nearest village is 2 km away."

But local protesters and civic groups refused to accept the findings, which they dismissed as "perfunctory" and only aimed at vindicating the Defense Ministry.

An Environment Ministry official said, "We've cross-checked the earlier provisional assessment. The only thing left now is for experts to review the figures and give their final opinion by the end of this month."

Once that is done, it will be possible to level the ground for the remaining launchers and build barracks and other facilities, including connecting to the power grid.

At the moment helicopters have to airlift fuel for emergency power generation every day over the heads of the protesters. The radar and the first two launchers were deployed on April 26 but run on a generator because there is no high-voltage power connection.

Originally, Cheong Wa Dae and the Defense Ministry had planned to put off full deployment until after a full-scale environmental study that is supposed to take about a year, a step which the previous administration skipped in its haste to deploy the THAAD battery. But Moon approved a temporary full deployment right after North Korea test-launched a Hwasong-14 intercontinental ballistic missile on July 28.

The Defense Ministry spokesman pledged not to repeat the mistake of the last government, which deployed the first two launchers at dead of night, but try to persuade locals.