He was appointed to the latter position by United Nations Secretary-General Ban Ki-moon in October 2007, as successor of Pierre Schori from Sweden.

[5] A career diplomat, before being appointed Special representative of the Secretary-General for Côte d'Ivoire, Choi has served in various capacities in the foreign service of the Republic of Korea.

From 1995 to 1997, Choi was Deputy Executive Director, Korean Peninsula Energy Development Organization (KEDO) in New York City.

UNOCI undertook military operations using Mi-24 armed helicopters to prevent Gbagbo's forces from using heavy weapons against the civilian population, in conformity with United Nations Security Council Resolution 1975 (2011).

These air-strikes were the first ever in the history of United Nations Peacekeeping and were also considered as pivotal in bringing about the dénouement of the Ivorian post-electoral crisis several days later.