The official was identified last may by US media as Andrew Kim, a former South Korean citizen who moved to the US with his parents when he was 13 years old. According to sources, Kim joined the CIA after graduating from college and rose through the Agency’s ranks to serve its stations in Moscow, Beijing and Bangkok. His most recent overseas post was reportedly in Seoul, where he served as the CIA’s station chief —the most senior American intelligence official in the country.

Following his return to the US from Seoul, Kim reportedly retired, but returned last year to head the CIA’s new Korea Mission Center (KMC). The purpose of the specialized unit is to analyze Pyongyang’s ballistic missile and nuclear weapons programs, which the administration of US President Donald Trump considers as matters of priority for the White House. It was as head of the KMC that Kim reportedly met Mike Pompeo once he became Director of the CIA in January 2017. The two men worked closely together and it is believed that Kim’s role was instrumental in organizing the negotiations between Washington and Pyongyang that led to last summer’s historic high-level meeting between President Trump and Supreme Leader Kim Jong-un. According to American and South Korean media, Kim accompanied the then-CIA director on his secret trip to North Korea. He also accompanied Pompeo on his trips to North Korea once the Kansas Republican became Secretary of State.

The Yonhap News Agency said on Tuesday that Kim initially intended to leave his CIA post in the summer, but was persuaded by Secretary Pompeo to continue. However, he has now tendered his resignation, which will take effect on December 20. Citing “multiple sources”, including “a senior official at South Korea’s National Intelligence Service”, the Seoul-based news agency said that Kim plans to take up an academic post at Stanford University, adding that he intends to continue serving as an adviser to the secretary of state. Prior media reports have stated that “Kim is widely viewed as a hawk on North Korea”, so there are suspicions that his departure from the CIA stems from his disagreement with the policy of negotiation signaled by President Trump. However, the CIA has not commented on the Yonhap report. The South Korean agency said that the CIA is already reviewing candidates to succeed Kim.