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"It has been a terrible year for principles of the UN Charter, from barrel bombs, to beheadings ... to attacks on UN schools," Moon said referencing a series of conflicts around the world including in Syria and the Gaza strip.
Moon went on to say these conflicts illustrated the fragility of global states and institutions. He also described a "rise of divisive politics."
US President Barack Obama is due to take the stage at 10 a.m.
(This post was updated at 9:34 a.m.)