"North Korea's most important objective is the maintenance of its regime and socialism," Defense Agency director-general Shigeru Ishiba said in a television interview.

But "if North Korea thinks that speaking out on its possession of nuclear weapons will help maintain the current regime, it is a big miscalculation," he said.

US officials told the Japanese government that North Korea said it possessed nuclear weapons at three-way nuclear talks in Beijing with the United States and China, which ended Friday.

"We have long said we cannot rule out possibilities that they are developing nuclear weapons and even possess them," Ishiba said.

"Therefore, the Japanese government was not shocked by their remarks," he said.

"But we have to remember that nuclear weapons development is totally different from possession of nuclear weapons and capabilities to load them on a missile," he added.

Ishiba said Japan was unlikely to counter North Korea's nuclear threat by developing its own atomic arms.

"I never support such a discussion that we will possess nuclear weapons because North Korea possesses them," he said.

He also said Japan would join multilateral talks in the future on the North Korean crisis as Tokyo should play a key role in economic pressure on North Korea.

"When we put economic pressure on North Korea, the United States will not be an actor as the United States has almost no economic relations," Ishiba said.

"The actors are those which have economic relations with North Korea," he said.

"Japan will join the multilateral talks sometime in the future as Japan has close economic relations," he said. "Japan will be a key player. Without Japan, North Korea cannot be pressured."

Ishiba said economic support for North Korea will be offered only when North Korea resolves the nuclear issue as well as returns Japanese nationals kidnapped by North Korean agents during the Cold War years.

North Korea allowed five Japanese to return to Japan last year, but has refused to release their family members and other kidnapped Japanese still living in North Korea.

The current crisis stems from US revelations made last October that North Korea was pursuing a secret nuclear weapons drive in breach of international accords, including the 1994 Agreed Framework between Washington and Pyongyang.

North Korea has ratcheted up tensions, expelling international nuclear inspectors, testing missiles and announcing its withdrawal in January from the Non-Proliferation Treaty.

North Korea has asserted that its very existence is threatened by US plans to launch nuclear war against the isolated and impoverished country, branded by US President George W. Bush as part of an "axis of evil" along with Iran and Iraq.

SPACE.WIRE