Trilateral cooperation between South Korea, Japan and the United States is reaching unprecedented levels thanks to the leadership of South Korean and Japanese leaders, a senior US administration official said Friday, calling it a "huge innovation" that helps promote peace and stability in the region.

Ely Ratner, assistant secretary of defense for Indo-Pacific security affairs, noted the three countries are also seeking to institutionalize their defense cooperation.

"I think ... arguably the most important innovation and new trend in the regional security environment in so far is these types of groupings are starting to actually do things together," he said while speaking about the US network of alliances in the Indo-Pacific region during a seminar hosted by the Brookings Institution, a nonprofit organization based in Washington.

"This isn't just about getting together and having dialogue and sharing views," he added.

Ratner highlighted that the US, South Korea and Japan are talking about sharing "early missile warning data" amid unprecedented ballistic missile tests by North Korea.

"We are developing plans for more regularized exercises rather than just exercises in response to DPRK activities," he told the seminar, calling them "huge, important innovations to institutionalize and really cement that kind of cooperation."

DPRK stands for the Democratic People's Republic of Korea, North Korea's official name. Pyongyang launched a record 69 ballistic missiles in 2022, the largest number of ballistic missiles it fired in a single year.

Daniel Kritenbrink, assistant secretary of state for East Asian and Pacific affairs, stressed the importance of multilateral cooperation in dealing with challenges in the region.

"It starts with our bilateral treaty alliances and our many partnerships across the region, but then it extends to the unprecedented level of trilateral cooperation that we have achieved with Tokyo and Seoul, I think, based mostly on the historic rapprochement that has taken place between the two of them," he said of the importance of trilateral cooperation among the US, Japan and South Korea.

Kritenbrink added the US commends South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida for their leadership in mending ties between their countries, which he said "really unlocked the unprecedented trilateral cooperation that we see now."