Moon Jae-in of the Democratic Party of Korea has just been elected South Korea's new president. This is the second conservative-to-liberal transition of power in the country's democratic history. It began unexpectedly last October, with the eruption of a corruption scandal involving then-President Park Geun-hye, culminating in her impeachment and removal from office earlier this year. Although Park's ouster was painful, it also demonstrated the resilience of South Korea's democracy.

Moon takes office at a time of heightened tensions with North Korea. To understand what kind of policy he will pursue requires familiarity with liberal foreign policy thinking in South Korea since the 1998-2003 presidency of Kim Dae-jung.

Kim had watched the Cold War come to a peaceful end in Europe, and he wanted to bring his own country's confrontation with the North to a similarly nonviolent conclusion. So he pursued direct engagement with North Korea, and his Sunshine Policy was taken up by his successor, Roh Moo-hyun. Before he died in 2009, Roh (under whom I served as foreign minister) was a political mentor and close friend to Moon.