The White House is expected to announce the nomination of Sung Kim as the replacement of current U.S. ambassador to South Korea Kathleen Stephens.

Kim reportedly has begun preparing for his confirmation hearing at the Senate after the South Korean government gave its formal consent to his nomination.

Meanwhile, foreign policy adviser to the Chief of Naval Operations Clifford Hart has been nominated to replace Kim to become the new U.S. special envoy for the six-party talks.

Hart is a career diplomat and an expert on China. In the past, he has handled issues related to China and Taiwan at the State Department.