 He served in the latter position until May 2008, when he was appointed Permanent Representative to the United Nations.In his latter role, Sin has been tasked with expressing North Korea's positions on the issue of his country's nuclear activities.In October 2008, Sin told a session of the General Assembly that North Korea had developed nuclear weapons in response to the threat it perceived from the United States, but that it had begun dismantling its nuclear apparatus and that it supported the "denuclearisation of the Korean peninsular".