North Korean leader Kim Jong Un has said an elevated U.S. security partnership with South Korea and Japan poses a grave threat to his country and vowed to further bolster his nuclear weapons program.

"I never expected to meet you at this place," said Kim to Trump. The US president had organised the last-minute rendezvous on Twitter, as it was then known, just 30 hours earlier when he suggested meeting Chairman Kim at the DMZ "just to shake his hand and say Hello (?