Deputy Foreign Minister Lee Soo-hyuck said on Thursday that the nature of the controversial uranium enrichment experiment conducted by South Korean scientists is totally different from that of North Korea's nuclear arms program. The official made the remarks before leaving for Tokyo to attend a preparatory meeting among South Korea, the U.S. and Japan for an envisaged fourth round of six-way nuclear discussions. Lee stressed that Seoul's uranium enrichment experiment, conducted four years ago, was a one-time research activity, while Pyongyang has previously admitted to operating a nuclear arms development program.