North Korea is on a quest to develop nuclear-armed ballistic missiles that can strike the United States, and the best way to counter Pyongyang is with combat power and strong alliances, the commander of U.S. forces in the Pacific said on Tuesday.

Admiral Harry Harris, the head of U.S. Pacific Command, told a South Korea support group in Washington that no threat in the region was "more dangerous than North Korea" and its leader Kim Jong Un.

"He recently threatened pre-emptive nuclear strikes against the United States and other countries in the region," Harris said. "Folks, make no mistake about it. North Korea is on a quest for nuclear weapons, the means to miniaturize them and the ways to deliver them intercontinentally."