The Sejong Institute held this year's 16th Colloquium on Tuesday, June 14, 2016 on the topic of "ROK's Diplomatic and National Defense Strategy amid North Korea Sanctions Regime and the U.S.-China Conflicts." The colloquium was moderated by Dr. Myon woo Lee who heads the Department of Security Strategy Studies, and our senior fellow Dr. Daewoo Lee presented his research findings. Participating as designated discussants were Dr. Haksoon Paik, Dr. Hyun-ik Hong, and Dr. Jaehung Chung who discussed about the security situation on the Korean Peninsula and in Northeast Asia as well as the measures strengthening South Korea's diplomatic and national defense strategies. Dr. Daewoo Lee contented that it is necessary (a) to strengthen trilateral security cooperation between South Korea, U.S., and Japan by renewing the ROK-Japan relations and tightening the ROK-U.S. alliance, (b) to promote Seoul's policy toward North Korea and gain active support from the international society by engaging in summit meetings and facilitating multilateral cooperation on North Korea sanctions, and (c) to prepare for measures of North Korea assistance in the case of Pyongyang's decision to rollback on its nuclear weapons program. During the follow-up discussion session, President Chang Soo Jin and other research fellows engaged in an active discussion on the topic.