The defense chiefs of Japan, the U.S. and South Korea on Sunday pledged to work together to realize the denuclearization of North Korea during a meeting in Singapore, with Defense Minister Takeshi Iwaya telling his counterparts that their gathering “is extremely important” and that the situation on the Korean Peninsula has drastically changed.

Iwaya issued the warning at the outset of the trilateral meeting on the sidelines of the Asia Security Summit, known as the Shangri-La Dialogue, as talks between Washington and Pyongyang remain stalled following U.S. President Donald Trump and North Korean leader Kim Jong Un’s failed summit in Hanoi in late February.

Acting U.S. Defense Secretary Patrick Shanahan and South Korean Defense Minister Jeong Kyeong-doo expressed eagerness to deepen trilateral cooperation to tackle issues related to the peninsula.

“The three ministers pledged that Japan, the ROK, and the United States will closely cooperate to support diplomatic efforts to establish complete denuclearization and permanent peace on the Korean Peninsula,” a joint statement issued by the three ministers read.

ROK is the acronym for the Republic of Korea, South Korea’s formal name.

“The U.S. reaffirmed its ironclad commitments to Japan and the ROK,” the statement added.

The three defense chiefs met for the first time since North Korea fired projectiles — which some experts believe were short-range ballistic missiles — on May 4 and May 9 in an apparent attempt to stir Washington into making concessions in denuclearization negotiations.

Iwaya told Shanahan and Jeong that Pyongyang’s recent actions were a clear violation of U.N. Security Council resolutions, and he called on the United States and South Korea to view it in the same way.

U.S. President Donald Trump said at a joint news conference with Prime Minister Shinzo Abe in Tokyo last week, “My people think it could have been a violation, as you know. I view it differently.”

South Korea, meanwhile, has remained silent on whether it has determined the projectiles were ballistic missiles or not, an indication that Tokyo, Washington and Seoul are still divided over how to address the issue.

U.N. Security Council resolutions prohibit North Korea from launching any type of ballistic missile.

Meanwhile, during separate bilateral talks on Saturday, Iwaya asked Jeong to prevent a recurrence of a radar lock-on incident that occurred late last year, expressing eagerness to end discussions on the issue that has led to worsening ties between the two neighbors.

“I believe there is only one truth” but Japan and South Korea “should take one step further based on a future-oriented viewpoint,” Iwaya told reporters the same day after he spoke with Jeong for more than 30 minutes in Singapore.

Jeong again rebuffed Japan’s allegation of the radar lock-on.

The minister, however, said that he and Iwaya exchanged views “in a candid manner” and that Seoul will make active efforts to improve relations with Tokyo.

As tensions on the Korean Peninsula have been rekindled following the breakdown of the second U.S.-North Korea summit in Hanoi in late February, Tokyo and Seoul may be leaning toward improving bilateral relations, diplomatic sources say.

The defense chiefs of the two countries held in-depth talks for the first time since a South Korean destroyer allegedly locked its fire-control radar on a Japanese patrol plane flying over the Sea of Japan near the Noto Peninsula, in Ishikawa Prefecture, last December.

Iwaya and Jeong also chatted together on Friday night at the venue of the ceremony of the three-day meeting, which will end Sunday.

Strains between Tokyo and Seoul have been running high especially after the radar lock-on incident.

In January, Japan concluded that South Korea’s denial of the alleged radar lock was “baseless” and had cut off any discussion about the incident since.

Seoul, meanwhile, claimed that Japanese Self-Defense Force planes deliberately flew at low altitude near South Korean naval vessels multiple times, terming the acts a “clear provocation.”

The two nations have also been engaged in several disputes based on differing interpretations of thorny issues related to history, such as recent rulings by South Korea’s Supreme Court ordering Japanese companies to pay compensation for work done by Korean nationals during Japan’s colonial rule of the peninsula.

A series of court rulings in South Korea have ordered Japanese companies to compensate for what Seoul calls forced labor during Japan’s 1910-1945 colonization of the Korean Peninsula.

Tokyo has argued that the issue of wartime compensation was resolved by a 1965 treaty that established diplomatic ties between the two countries, under which Japan provided South Korea with $500 million in financial aid.

With bilateral relations showing little sign of improving, North Korea fired projectiles that appeared to be short-range ballistic missiles on May 4 and 9, fanning fears about peace and stability in the region.

In the wake of Pyongyang’s missile launches, Tokyo and Seoul may have started to consider the possibility of talks, the sources said.