VIENNA, June 13, 2016 (Xinhua) -- (R to L) European Union (EU) foreign policy chief Federica Mogherini, International Atomic Energy Agency's (IAEA) Director-General Yukiya Amano and Director General of the United Nations Industrial Development Organization (UNIDO) Li Yong attend the 20-year anniversary of the Comprehensive Nuclear-Test-Ban-Treaty (CTBT) in UN headquarter in Vienna, Austria, June 13, 2016. (Xinhua/Qian Yi)