Singapore President Tony Tan Keng Yam (R front) presents an Honorary Degree of Doctor of Letters by the National University of Singapore (NUS) to UN Secretary-General Ban Ki-moon (L front) at Singapore's Istana, on Aug. 30, 2016. United Nations Secretary-General Ban Ki-moon was conferred an Honorary Degree of Doctor of Letters by National University of Singapore (NUS) on Tuesday during his two-day visit to the city state. (Xinhua/Then Chih Wey)
