China's President Hu Jintao (R) shakes hands with US President Barack Obama during an expanded bilateral meeting before attending the 2012 Nuclear Security Summit in Seoul March 26, 2012. [Photo/Xinhua]

Jordan's Princess Raiyah (L to R), Jordan's King Abdullah, South Korean President Lee Myung-Bak, Jordan's Crown Prince Hussein and Prince Rashed bin al-Hassan pose during a bilateral meeting in Seoul March 25, 2012 on the eve of the 2012 Seoul Nuclear Security Summit. [Photo/Agencies]