US President George W Bush and presidential candidate John Kerry have clashed over how to handle the North Korean nuclear stand-off.
It was the first of three televised debates between the US candidates
In a televised debate ahead of November elections, Mr Bush defended his six-nation talks approach while Mr Kerry backed bilateral talks with the North.
Both agreed the US' greatest security threat was nuclear proliferation.
Analysts believe Pyongyang is waiting to see who is the next US president before it makes its next move.
"I want bilateral talks which put all of the issues, from the armistice of 1952, the economic issues, the human rights issues, the artillery disposal issues, the DMZ issues and the nuclear issues on the table," said Mr Kerry.
Mr Bush responded: "I can't tell you how big a mistake I think that is to have bilateral talks with North Korea. That's precisely what Kim Jong-il wants."
He argued that face to face talks between the US and North Korea would "unravel" the current framework, which brings pressure on Pyongyang from its traditional ally China, in addition to Japan, Russia, and South Korea, as well as the US.
"If Kim Jong-il decides not to honour an agreement, he's not only doing an injustice to America, he would be doing injustice to China as well. And I think this will work," said Mr Bush.
The current administration believes the bilateral approach taken by former President Bill Clinton gave too much to Pyongyang in exchange for too little.
But Mr Kerry argued that Mr Bush's approach was not working, and had given Pyongyang the time to build up its nuclear arsenal.
"Today there are four to seven nuclear weapons in the hands of North Korea," he said.
Analysts believe Pyongyang may be waiting to see who will win the November elections before it makes its next move. It has refused to take part in a fourth round of six-nation talks which was planned for this month.
But US Secretary of State Colin Powell stressed on Thursday - after talks with his Chinese counterpart - that Washington was still committed to this mechanism.
"I'm quite confident that the six-part framework is a framework in which this matter will be dealt with for the foreseeable future, because it serves the interests of all parties," Mr Powell said.
He said that North Korea's neighbours in particular had "an even greater equity in seeing a denuclearised peninsula than does the United States".
Chinese Foreign Minister Li Zhaoxing, standing at his side, said the "entire international community" agreed that the six-nation approach was the best way to deal with the problem.
While acknowledging that there "were some complicating factors and new difficulties" that hampered the talks, Mr Li stressed that "nothing is more precious than peace".
He did not elaborate on what the "complicating factors" were.
Seoul's secret tests
The talks on the nuclear stand-off have been put on hold since Pyongyang made clear its dissatisfaction with Washington's stance.
Pyongyang has also been pressing for a full probe into South Korea's recent admission that its scientists had carried out secret nuclear experiments.
The nuclear stand-off intensified in 2002 when Washington accused Pyongyang of operating a nuclear weapons programme based on enriched uranium in violation of a 1994 agreement.
North Korea has denied running the uranium-based programme but its officials have recently said the country turned plutonium from 8,000 spent fuel rods into nuclear weapons.