Other steps toward the installment of the U.S. missile defense system have already been taken, including an environmental assessment.
On Tuesday, eight military helicopters were seen flying over the Lotte-owned golf course in Seongju, in central South Korea.
The Chinook multi-mission choppers were transporting equipment for THAAD, Yonhap news agency reported.
A military official who spoke on the condition of anonymity confirmed the deployment.
"We have been preparing materials and equipment needed for THAAD, the materials were moved in containers," the official told Yonhap, adding air transport was used in order to "reduce friction with residents."
In March, Seoul's military and environmental authorities were met with some resistance, when local residents blocked a road being used to transport a large truck carrying equipment for environmental testing.
Activists with the Seongju Struggle Committee to Stop THAAD Deployment said Tuesday the military moved two bulldozers, one excavator, two containers and two water tanks.
The group is protesting the deployment and described it as an "illegal move" that is being "carried out without an environmental impact assessment."
South Koreans are evenly divided about deployment: A poll taken in January indicated about 51 percent of respondents support THAAD.
But officials in Seoul are moving forward on THAAD in coordination with the U.S. military.
A handful of presidential candidates also voiced their complaints to a visiting Chinese official on Tuesday, local newspaper Segye Ilbo reported.
Beijing may have sanctioned South Korea business activities in China and blocked Chinese tourism to South Korea.
Wu Dawei, the Chinese envoy on Korean peninsula affairs, agreed to impose heavier sanctions against North Korea, but also stressed dialogue while expressing continued opposition to THAAD deployment, according to the report.