South Korea\'s chief nuclear negotiator will visit the United States next month to discuss recent developments in efforts to restart the stalled six-party talks on ending North Korea\'s nuclear weapons program, government officials here said Sunday. Cho Tae-yong, Seoul\'s chief envoy to the six-party talks, will make a series of visits to the U.S. and China next month as the sides try to coordinate their positions on the conditions for the reopening of the talks, the officials said.