The U.S. Pacific commander called Tuesday for greater trilateral military cooperation with South Korea and Japan as the three countries plan to hold their first joint missile-tracking exercise to better defend against North Korea.

Adm. Harry B. Harris Jr. made the remark during a speech at a security seminar in Washington, saying the North is posing a "real threat" with its pursuit of nuclear weapons and delivery missiles in addition to "hundreds of thousands of rockets within range of Seoul."

He also said that "no threat is more dangerous than North Korea."

"The best way to effectively counter North Korea's aggression is through incredible combat power, unrelenting resolve in the face of provocations and sustained partnerships with our closest allies," the commander said during the seminar hosted by the Institute for Corean-American Studies (ICAS).

"This is a big reason why I'm doing everything possible to encourage trilateral cooperation with Japan and the Republic of Korea. The current level of military cooperation between Japan, South Korea and the U.S. is good, but I'd like it to get better," he said.

The U.S. has long sought to bolster trilateral security cooperation with South Korea and Japan as a counterbalance to China's rise, leading efforts to put together the three-way military intelligence sharing agreement signed in late 2014.

Such efforts got a boost from a landmark agreement between South Korea and Japan in late December on resolving the issue of Japan's wartime sexual slavery, a major thorn that had soured not only relations between the two countries, but also three-way cooperation with the U.S.

Harris applauded the two countries for having the "courage and vision to settle this difficult, historic issue."

Next month, the three countries plan to hold an anti-missile exercise in Hawaii to better counter North Korea's ever-growing nuclear and missile threats. The maneuvers will take place on the sidelines of the Rim of the Pacific (RIMPAC) exercise, U.S.-led biennial multinational naval wargames.

It will be the first anti-missile drills between the countries.

"I'm excited by the opportunity to conduct the exercise and I look forward to learning about the capabilities of each of the countries when we work together. I think the most important thing is that we're going to learn how we can improve and we won't know that until we do the exercise," Harris said.

"But it's not this exercise that's the most important. It's the next one, because the next one will hopefully apply what we learn during this exercise to make our ability to operate together in a ballistic defense environment better," the commander said.

Harris also said that the U.S. THAAD missile defense system will be of "particular utility in areas like the Korean peninsula," and that he is pleased that the two countries have begun formal discussions on whether to bring the system to the South. (Yonhap)