Harris will serve as Washington's top envoy to Seoul at a time when the allies have been seeking close coordination on a range of issues, including North Korea's nuclear weapons program and bilateral trade.

At his confirmation hearing earlier this month, Harris expressed support for Trump's decision to suspend joint military exercises with South Korea while the US negotiates the dismantlement of North Korea's nuclear weapons program.

"I believe we should give exercises, major exercises, a pause to see if Kim Jong-un is in fact serious about his part of the negotiations," he said, referring to the North Korean leader.

"Today, following the summit, we are in a dramatically different place."

Trump and Kim met in Singapore on June 12 and committed to the "complete denuclearization" of the Korean Peninsula in exchange for security guarantees from the US  

The Navy admiral was born in Japan to a Japanese mother and American father. He led the US Pacific Command in Hawaii for three years until last month, with oversight of the 28,500-strong US Forces Korea.

On foreign policy issues, he is considered a hawk, along with some of the latest additions to Trump's national security team – Secretary of State Mike Pompeo and National Security Adviser John Bolton.