South Korea said on Tuesday it would be difficult to make actual progress at the six-nation talks, if they are resumed, unless the U.N. Security Council defines North Korea\'s uranium enrichment program as illegal. Following years of adamant denials, North Korea revealed its industrial-scale uranium enrichment plant last November, creating new hurdles to efforts by regional powers to resume the six-party talks involving the two Koreas, the United States, China, Japan and Russia. South Korea and its ally the United States had wanted to take the North\'s uranium program, which could give the communist regime a new source of fission material to make atomic bombs, to the Security Council for new sanctions, but China opposed the move, arguing that the issue can be handled at the six-party talks, according to South Korean officials.