Clinton said Friday she's certain North Korea will try produce enriched uranium to advance its nuclear ambitions in the future but "no one can point" to specific locations or programs.
The secretary of state made the comments during an interview with Fox News in Seoul.
"I don't have any doubt that they would try whatever they possibly could," Clinton said. "Have they? I don't know that, and nobody else does either."
U.S. intelligence officials have said they were confident North Korea ran an enrichment program at one time and that the program could still exist.
Officials had "some reason to believe that something having to do with highly enriched uranium" was part of the information made available once inspectors began their work in North Korea, she said, adding that "what we do know for sure is that they ... reprocessed plutonium."
Clinton wouldn't say if President George Bush's removal of North Korea from the U.S. list of state sponsors was good or bad because "that is part of the process that we're engaged in right now" to jump-start negotiations among the Koreas, Japan, the United States, Russia and China.
"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," Clinton said.