A South Korean protester sits next to a poster with an illustration of U.S. President Donald Trump to oppose a plan to deploy an advanced U.S. missile defense system near the U.S. Embassy in Seoul June 5. (Ahn Young-Joon/AP)

South Korea has suspended the deployment of a controversial American missile defense system, with the new liberal administration declaring that no further moves can take place until an environmental assessment is carried out — a process that could take a year or even two. 

The decision highlights the potential for a rift between the United States under President Trump and South Korea with its new liberal president, Moon Jae-in, who is due to visit the White House later this month for their first meeting. 

Moon’s office Wednesday said it would suspend the deployment of the Terminal High Altitude Air Defense (THAAD) system. The antimissile battery is designed to protect the South against North Korea, but it has elicited strong opposition, particularly where it is being deployed. 

The U.S. Army expedited the movement of the THAAD battery to South Korea ahead of Moon’s anticipated victory in a snap presidential election last month. Moon vowed to review the previous government’s decision to host the system. 

Two launchers and the powerful X-band radar were already in place before his victory on May 9, but Moon expressed outrage last week when it emerged that four more launchers had been brought into the country without his knowledge. 

A full THAAD battery contains six launchers mounted on trucks, each capable of firing eight interceptor missiles. But Moon’s office accused an official in the Defense Ministry of deliberately failing to tell the president’s staff about the arrival of the final four launchers. Moon called the omission “very shocking” and ordered an investigation. A deputy defense minister was suspended as a result. 

An official from the president’s office said Wednesday that the missile defense system would be frozen as it is.

“We are not saying the two launchers and other equipment that has already been deployed should be withdrawn. But those that have yet to be deployed will have to wait,” a senior official told reporters in Seoul, according to the Yonhap News Agency.

Gary Ross, a Pentagon spokesman, suggested that the deployment should be above politics.

“The U.S. trusts the [South Korean] official stance that the THAAD deployment was an Alliance decision and it will not be reversed,” Ross said. “We will continue to work closely with the [South Korean] government throughout this process.”

The president has ordered a full-blown environmental impact assessment of the deployment, on the grounds of a former golf course in the southern area of Seongju.  

The unnamed official said the assessment could take at least a year, or perhaps two, noting that a similar evaluation for a THAAD deployment in Guam had taken 23 months, Yonhap reported. 

But there was no hurry to get the system up and running, given that North Korea has been a threat to the South for years, the official said.

“[North Korea’s] nuclear tests have been going on for a long time, and so whether we must urgently install [the THAAD battery] by ignoring our legal procedures is a question,” he said. 

North Korea has been test-firing missiles in quick succession recently, apparently part of an avowed plan to develop an intercontinental ballistic missile capable of reaching the mainland United States. 

As if to underline the threat, North Korea launched a salvo of missiles Thursday morning, although they appeared to be cruise missiles rather than the ballistic missiles it has been firing recently.

“North Korea fired multiple unidentified projectiles, assumed to be surface-to-ship missiles, this morning from the vicinity of Wonsan,” South Korea’s Joint Chiefs of Staff said Thursday, according to local media. They flew about 125 miles, it said. Wonsan is on North Korea’s east coast, on the sea between the Korean Peninsula and Japan, and has been the site of several recent launches.

Most of the previous launches have been medium- or intermediate-range missiles that can reach all parts of South Korea. The THAAD system was deployed to intercept those missiles, but it has greatly angered Beijing, which is concerned that its powerful radar will be used to spy on China.