The Nuclear Security Summit started here today with the participation of 53 world leaders and heads of delegations in addition to five international organizations including the United Nations. Marking the opening of the summit, President Lee Myung-bak of South Korea held a working dinner in honor of the participants, including Dr. Hashim bin Abdullah Yamani, the head of Saudi delegation to the Nuclear Security Summit and President of King Abdullah City for Atomic and Renewable Energy. The summit will tackle international issues and challenges and make a comprehensive review of progress that have been achieved since the 2010 Washington Summit.