Here is more from Josh Rogin of the Washington Post:
Kim Ki-jung, former Moon adviser who is now president of the Institute for National Security Strategy, a government-funded think tank, told me in an interview that [President Joe] Biden must recognize there is an opening and act boldly [on negotiations with North Korea].
The Institute for National Security Strategy (INSS) was founded in 1977, and has more than a dozen North Korean defectors as well as around 50 experts as in-house researchers. Reports indicate that INSS is an affiliate of South Korea's National Intelligence Service (NIS).
Kim Ki-jung was chosen as new president of the think tank in 2020, raising eyebrows due to his close relationship to President Moon Jae-in and the fact that he was embroiled in misconduct allegations in the past.