The recent nomination of a South Korean-born American diplomat as the new U.S. ambassador to South Korea is a positive development for relations between Seoul and Washington, diplomatic sources said Sunday. The Barack Obama administration tapped Sung Kim, the State Department\'s top Korea expert, as its new top envoy to Seoul, according to sources in Washington on Saturday. If his nomination is confirmed by the Senate, the 51-year-old diplomat will become the first person of Korean descent to be appointed U.S. ambassador to South Korea.