The de facto inception of the installment of a US missile shield on Wednesday was met with mixed responses from South Korea’s presidential candidates, prompting even some advocates to take issue with the unanticipated move and the lack of a related environmental impact assessment.

The planned stationing of the Terminal High Altitude Area Defense system has been one of the biggest sources of debate in the election race, with security and foreign policy ascending on the agenda in the face of North Korea’s escalating threats.

Of the five major contenders, Yoo Seong-min of the conservative splinter Bareun Party and Hong Joon-pyo of the far-right Liberty Korea Party support the deployment plan, while the far-left Justice Party’s flag-bearer Sim Sang-jeung opposes it. Ahn Cheol-soo of the center-left People’s Party has shifted his stance in favor of it, deserting his initial resistance. Front-runner Moon Jae-in of the progressive Democratic Party of Korea clings to a reserved stance that the next government should make the final decision, though he has recently turned a bit more supportive.

Shortly after the announcement on the deployment of key parts, the campaigns of Moon and Sim issued criticism.

“I don’t think it’s something the government should push ahead with by constraint ahead of the presidential election,” Moon told reporters after visiting an Army live-fire drill in Pocheon, Gyeonggi Province.

“It’s desirable to pass it to the next government so as to use it as a diplomatic bargaining chip on various issues, especially the North Korean nuclear program.”

Moon’s spokesperson Park Kwang-on earlier expressed “strong regret,” saying the decision snubbed public opinion and the due process.

“The fact that the equipment was brought in even before an environmental impact assessment was done and in disregard of the residents’ opposition means that the THAAD deployment is taking place without following basic procedures, not to mention public consensus,” Park said at a news briefing.

“This would completely block the next government’s leeway for a policy decision, which is extremely inappropriate,” he added, calling for the Defense Ministry to cease the process.

Sim adopted a tougher tone, calling the move “unacceptable and invalid” and saying the next government should reassess the program “from square one.”

“The sudden deployment amounts to violence with which to thwart our people’s right to self-determination and trample sovereignty,” she wrote in a Facebook post.

While vowing to hold the Defense Ministry accountable, Sim blamed the Park Geun-hye government and opposition leaders -- namely Moon and Ahn -- for having failed to secure national consensus and flip-flopping on the THAAD issue.

Ahn, for his part, reaffirmed his support for the program but expressed concerns about its potential environmental impact and the reported violence involving residents in Seongju, North Gyeongsang Province, where the assets will be located.

“The THAAD should be deployed in line with the agreement with the US,” he told reporters during a rally in Chuncheon, Gangwon Province.

“But it’s a problem that they skipped the environmental impact assessment. I’m also worried that there was a clash with the residents.”

Ahn’s People’s Party released a separate statement displaying regret over the surprising late night placement and calling for “due process and careful discussions” with the residents.

In contrast, Hong and Yoo welcomed the move, saying the early stationing would help curb further political and public disputes.

THAAD is the “best defensive weapon available” to counter North Korea’s evolving nuclear and missile threats, and will hopefully be in complete operation within this year, said Kim Myung-yeon, chief spokesperson for Hong’s Liberty Korea Party.

“We no longer need consumptive debate, just like those who resist it or say it’s a job for the next government,” he said in a commentary.

Yoo echoed the view, calling for Moon and Ahn to stop flip-flopping on THAAD and work together to resolve the North Korean threats that have raised the need for the system.

“I’ve been arguing for a long time that (THAAD) should be deployed before the election because it’s the way to prevent a spilt in public opinion. They’ve made a good decision,” he told reporters on the sidelines of a rally in Seoul.

“It’s a matter of military and security sovereignty. Through diplomacy with China, we need to make it clear as much as possible that the deployment has nothing to do with them and strive to promote China’s understanding so that its economic retaliation will be lifted as fast as possible.”

By Shin Hyon-hee (heeshin@heraldcorp.com)