According to Seoul's defense ministry and the US Forces Korea, helicopters will transport construction materials, equipment and containers into the Seongju base to avoid confrontations with residents and civic activists opposed to the deployment of THAAD in South Korea.

One helicopter will bring a container into the base Friday, while other choppers will transport replacement troops and food supplies as usual, they said, adding the new construction work will last about four to five months.

Containers will be used as a temporary accommodations during the construction.

The renewed construction at the Seongju base drew particular attention following a string of missile firings by North Korea over the past week.

The THAAD base has two accommodations -- one exclusively used for American troops and the other shared by Korean and American soldiers.

This time, the shared accommodation, which was formerly used as a golf course clubhouse, will undergo a transformation that includes the removal of locker room walls and baths, the installation of small shower stalls and noninflammable building materials, and the replacement of air conditioners and water purifiers, a ministry official said.

Between 2017 and 2018, the two countries' militaries transported THAAD launchers and construction equipment on six occasions, which resulted in injuries to about 10 people during clashes between protesters and police.

"Last year, water leaks in the accommodation roofs were repaired, and water treatment facilities were replaced," the ministry official said. "This time the dilapidated and cramped accommodation will be repaired to improve the living conditions of the soldiers stationed there."

About 50 residents in Seongju and neighboring Gimcheon held a protest rally at the entrance of the THAAD base Friday afternoon, calling for an immediate end to the construction. (Yonhap)