WASHINGTON -- The US missile defense system deployed in South Korea, THAAD, is a purely defensive system that is only designed to protect South Korea and its people against threats from North Korea, a state department spokesperson said Monday.

Vedant Patel, principal deputy spokesperson for the department, also insisted any call or demand from other countries to withdraw THAAD would be "inappropriate."

"THAAD is a prudent and limited self defense capability designed to counter a DPRK weapons program," Patel said in a telephonic press briefing.

"Criticism or pressure on the ROK to abandon its self-defense is inappropriate," he added, referring to South Korea by its official name, the Republic of Korea.

His remarks come after South Korea announced that the country has formed a consultative body to assess the environmental impact of the US THAAD system deployed in Seongju, located some 300 kilometers south of Seoul, a move that Seoul officials said will help "normalize" the operation of the THAAD system.

South Korea decided to host the US missile defense system in 2016 at the height of North Korean nuclear and missile provocations, but the system has been operating in a status of "temporary installation" pending an environmental impact assessment.

The Yoon Suk-yeol administration, which came into office in May, has also hinted at the possibility of deploying additional THAAD units in South Korea following a series of North Korean missile launches this year.

Pyongyang has already launched more than 30 ballistic missiles this year, which mark the largest number of ballistic missiles it fired in a year, according to the US

"The US and the ROK made an alliance decision to deploy THAAD to the ROK as a purely defensive measure to protect the ROK and its people from armed attack and to protect alliance military forces from the DPRK's weapons of mass destruction and ballistic missile threat," said Patel.

The department spokesperson also called on Pyongyang to return to dialogue.

"We are prepared to meet with the DPRK without preconditions and we hope the DPRK will respond positively to our outreach," he said.

DPRK stands for the North's official name, the Democratic People's Republic of Korea. (Yonhap)