Secretary of State Hillary Clinton told FOX News that nobody knows whether North Korea ever tried to produce highly enriched uranium, despite claims seemingly to the contrary from intelligence officials. 

In an interview in Seoul, South Korea, on Friday, Clinton said she's certain the regime in North Korea would try  to produce the substance if it could to further its "nuclear ambition," but that the U.S. does not have solid evidence that any program exists or ever existed. 

"I don't have any doubt that they would try whatever they possibly could. Have they? I don't know that, and nobody else does, either," Clinton told FOX News. "Clearly, there was some reason to believe that something having to do with highly enriched uranium -- whether it was happening in North Korea, whether it had been imported into North Korea -- was part of the information derived once we got inspectors into North Korea," she said. 

Clinton said nobody can point to "any specific location" or "any specific outcome of whatever might have gone on, if anything did." 

Top U.S. intelligence officials have said they have high confidence that North Korea was running an enrichment program and moderate confidence the program could still exist. 

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But Clinton has stirred doubt about the threat posed by any such enrichment program during her four-country tour of Asia, her first trip abroad as secretary of state. 

She has urged those focused on it to remember that it was the reprocessing of plutonium that enabled the North to become a nuclear state. The North detonated a low-yield nuclear device in October 2006. That device, and the arsenal of six to 10 nuclear bombs the North is believed to possess, was developed through the reprocessing of plutonium. 

One of Clinton's chief aims this week is to reinvigorate the stalled Six-Party talks aimed at persuading Pyongyang to dismantle its nuclear programs. 

Late last year, in exchange for a verbal pledge by North Korea to allow tough inspections of its nuclear facilities -- on which the North later reneged -- the Bush administration removed the country from Washington's list of nations that sponsor terrorism. 

Clinton suggested the "de-listing" of the country could be reversed as they try to jump-start the talks. 

"This is still an open effort on our part to get the North Koreans back to the Six-Party talks. The role that that decision did play and might play in trying to engage them once again is of, you know, paramount concern to me right now," she told FOX News. 

Clinton's last stop -- after visiting Japan, Indonesia and South Korea -- is China

On another front, the war in Afghanistan, Clinton seemed unconcerned that the recent gathering of NATO defense ministers in Krakow, Poland, ended with America's allies agreeing to send only an additional 1,400 troops to the country. 

"We are only at the beginning of that process," she said. "I think a number of countries are waiting to see more specifically what our plan is, why we think their contribution of troops would be helpful." 

She said the U.S. wants "civilian help" from other countries as well. 

"We want their help training the Afghan army; we want their help training the Afghan police. So there's going to be a number of ways people can contribute," she said. 

FOX News' James Rosen contributed to this report.