HONOLULU (Yonhap) -- North Korea and the country's leader Kim Jong-un are the biggest sources of threat from the perspective of the United States' military command responsible for the Indo-Asia-Pacific region, a U.S. defense official said, vowing that Washington will not allow Kim to destabilize regional security.

The comments were made by Rear Adm. Mark Montgomery, director for operations at the U.S Pacific Command in Honolulu, Hawaii, during his meeting with a group of South Korean journalists on Tuesday (Hawaii time).

Kim is currently using the country's nuclear program as a means to show off its power, Montgomery said, adding that it remains to be seen whether North Korea could conduct an additional nuclear test following the latest one in January.

Asked how serious a threat North Korea's missile capabilities pose, he said the country has demonstrated the level of missile and rocket engine technology with which it could launch a projectile into space.

The flag officer said the U.S. and South Korea will take actions that are proportional to the development. He, however, did not specify what actions the allies are planning to take.

The official also highlighted how effective it will be in defending against North Korea's missile threats if the advanced U.S. air defense system, Terminal High Altitude Area Defense, is deployed on South Korean soil.

THAAD could intercept what the Patriot missile interception system cannot, the rear admiral said. He expressed hope that South Korea will reach a conclusion in favor of deploying the THAAD system.

He also said trilateral military cooperation between South Korea, the U.S. and Japan is necessary in dealing with any military crisis or an emergency situation on the Korean Peninsula.