Moon Jae-in is the man in the middle.
The South Korean president has become the mediator between Donald Trump and Kim Jong-un and is leading the diplomatic efforts to try to get North Korea to disarm.
Mr Moon's trip to Pyongyang on Tuesday, his third meeting with Mr Kim since April, may be his toughest challenge yet. He has to make real progress in persuading the North Koreans to make concrete steps to denuclearise. Otherwise the flurry of inter-Korean summits and the much-hyped Singapore meeting this year will be seen as glossy photo-ops, and President Trump may begin to lose patience.
With his approval rating dropping at home, Mr Moon needs a win. Here are some of the main obstacles he will need to overcome...
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