North Korea has jeopardized the future of its regime by saying that it possesses nuclear weapons, the Defense Agency director general said Sunday.

"It would be a grave miscalculation if (Pyongyang) believes that by saying it has nuclear (weapons), its political system will be maintained," Shigeru Ishiba said on a TV Asahi program.

"Conducting nuclear development, possessing nuclear weapons and miniaturizing the weapons to missile-mountable size are all different things," the defense chief said.

North Korea said during a meeting with the United States and China in Beijing on Wednesday that it possesses nuclear weapons and has started reprocessing spent fuel rods, which would enable it to make more nuclear arms, according to U.S. sources.

On whether the Tokyo-Pyongyang Declaration has become invalid in light of North Korea's statement, Ishiba said, "It can be interpreted in that way, but what's important is whether it's a plus or minus for Japan. We must place value on the points in (the declaration)."

Prime Minister Junichiro Koizumi and North Korean leader Kim Jong Il signed the declaration on Sept. 17, 2002, following summit talks in Pyongyang. By doing so they promised to comply with all related international agreements in resolving the nuclear issue.

If North Korea does possess nuclear arms, it would be in violation of the 1994 U.S.-North Korea nuclear accord in which Pyongyang pledged to freeze and dismantle its nuclear program in exchange for construction of two light-water nuclear reactors and a supply of fuel oil.