Former US ambassador to the UN John Bolton said on Wednesday that six-way talks on North Korea's nuclear arms had failed and a breakthrough would only come after the collapse of Kim Jong-Il's regime.
"Six-party talks have not worked. They are not likely to work," said the blunt-talking former diplomat, who relinquished his UN post in December in the face of strong opposition to his nomination by opposition Democrats.
In a speech to reporters in Tokyo, he said North Korea was unlikely to voluntarily give up nuclear arms.
World powers "need to do something different in order to prevent North Korea from becoming an even greater threat to the region and around the world than it already is," said Bolton, now a senior fellow at the American Enterprise Institute, a conservative think tank.
The six-party talks, which group the two Koreas, China, Japan, Russia and the United States, were launched in 2003 in a bid to persuade Pyongyang to abandon its efforts to develop nuclear weapons.
However, North Korea carried out its first nuclear test on October 9 last year, and the latest round of the talks in December ended in deadlock as Pyongyang insisted financial sanctions be lifted before it would discuss nuclear disarmament.
"I think, realistically over time, the only answer to the North Korean nuclear weapons programme is the collapse of the regime and North Korea, and hopefully a peaceful reunification of the Korean peninsula," said Bolton.
China had invested much in the talks, only to see failure, Bolton said. "I think continuing the failed process would cause even more embarrassment for China," he said.