Admiral Harris, confirmed by the U.S. Senate to be the U.S. Ambassador to South Korea, presented his credentials to President Moon on July 25, 2018. He served until 2021. Previously, he served 40 years in the U.S. Navy, retiring in June 2018. The first Asian-American to hold 4-star rank in the Navy, he commanded U.S. Indo-Pacific Command, U.S. Pacific Fleet, and U.S. Sixth Fleet. From 2011 to 2013, Harris served as the Assistant to the Chairman, Joint Chiefs of Staff where he was the Chairman's direct representative to the Secretary of State. Harris participated in Operations Attain Document, Earnest Will, Desert Shield/Desert Storm, Enduring Freedom, Iraqi Freedom, and Odyssey Dawn. He amassed over 4400 flight hours, including over 400 combat hours.

Harris’ personal decorations include the State Department’s Distinguished Honor Award and the CIA's Agency Seal Medal and Ambassador's Awards. He received South Korea's Tong-il and Gwanghwa Medals. He has also been decorated by Australia, France, Japan, Mongolia, the Philippines, and Singapore.

A 1978 graduate of the U.S. Naval Academy, he holds master's degrees from Harvard's Kennedy School of Government and Georgetown's School of Foreign Service. He serves on the board of directors of The Korea Society.