U.S. Undersecretary of State John Bolton reiterated Friday that North Korea must completely abandon its nuclear program, which he maintained is exclusively for military use.

"We don't think that there is any peaceful aspect to North Korea's nuclear program," Bolton told a news conference at the U.S. Embassy in Tokyo. "The only explanation we have for what they have been doing is associated with a weapons program."

Bolton, who oversees arms control and international security, stressed that North Korea must give up its nuclear development in a complete, verifiable and irreversible manner.

He stressed that verification is the key aspect of dismantling Pyongyang's nuclear program, adding that the International Atomic Energy Agency needs to have complete access to its facilities.

The five permanent members of the U.N. Security Council or participants in the six-way talks on the North Korea nuclear issue could take part in the verification process, he said.

The members of the six-way talks are North and South Korea, China, the United States, Japan and Russia.

China and Russia have said that North Korea should be allowed to develop nuclear energy for domestic power supply purposes and for other nonmilitary purposes.

Bolton charged that North Korea's proposal to freeze its nuclear program, offered at the last round of six-party talks in June, may only be a time-buying strategy.

"Once a strategic decision to give up weapons of mass destruction is made, you don't need a freeze," Bolton said, referring to Libya, which decided to abandon its weapons program last December. "You can directly move from the decision to verification to absolute dismantlement."

In a meeting earlier Friday with Foreign Minister Yoriko Kawaguchi, Bolton said the international community should continue to urge North Korea to abandon its nuclear program.