Two leading presidential candidates have showed inconsistent views on national security.

They have been changing their stances, with national security emerging as a hot campaign issue amid mounting military tension on the Korean Peninsula.

Moon Jae-in of the Democratic Party of Korea initially called for the government to review its decision to host the Terminal High Altitude Area Defense anti-missile system. He had opposed the US missile shield being deployed in Korea. Some figures in his camp had argued the system would aggravate the problem of North Korean nukes, echoing China’s opposition to the missile shield.

Later he toned down his position, saying the matter should be dealt with by the next government and that it should be ratified by the parliament. Then he changed from opposition to approval, as concerns over a US military clash with North Korea mounted.

“If North Korea continues provocations with atomic bomb tests and missile launches, THAAD may be deployed,” he said.

On Monday, he dropped his pledge to seek a parliamentary ratification of the THAAD deployment. In fact, the National Assembly has never dealt with the deployment of a defensive weapon as a matter requiring its approval.

Meanwhile, Ahn Cheol-soo of the People’s Party recently said he would keep trying to persuade the party to change its opposition to the deployment of THAAD.

Last year, when Korea and the US announced an agreement to install the system, he proposed the matter should be put to a national referendum. However, the accord was not an issue to be approved or rejected by a referendum. Criticism grew that voting on the deployment was an ill-informed proposal, and days later, he withdrew the offer.

Last October, he supported the system, saying the accord between the two countries should be respected. However, the People’s Party maintains its platform against THAAD. He tried to change the platform in February, but failed to persuade leading lawmakers of the party, who support the Sunshine Policy for economic cooperation with North Korea.

As Ahn’s approval rating rose, the party began to review its platform.

Moon seems to have changed his position on the system to reassure conservatives who feel nervous about his liberal views on national security. He has been criticized by the conservative camp for being friendly to North Korea.

For Ahn, it is hard to tell which position voters should believe, his or the People’s Party’s.

Ahn said it is problematic to emphasize national security for political benefits.

Of course, it is wrong to take advantage of tension on the Korean Peninsula to attract votes. However, using national security politically is one thing and vetting candidates’ views on security is another. When it comes to a matter concerning the lives of the people, detailed vetting is essential.

The two candidates’ move to the right raises questions among voters and fans conservative rivals’ criticism over their changes in position.

Whoever wins the election will face a hair-trigger security situation. The North seems to have paraded intercontinental ballistic missiles during a military review Saturday. Satellite images show it is set to conduct its sixth atomic bomb test. The US vows a strong response including a possible military option.

The next leader may have to decide on more grave security issues than the THAAD deployment. In light of the highly charged security environment, the next president may be required to mobilize all military and diplomatic capabilities of the nation.

Changing views on an issue vital to the survival of a nation to get votes is far from a desired presidential trait.

According to poll results so far, either Moon or Ahn will likely decide on the nation’s security issues as the next president. If they changed their positions due to the evolving situation, they should follow up with efforts to convince voters why they did so.