President Donald Trump embarked Wednesday on another round of high-stakes nuclear diplomacy with North Korea's Kim Jong Un.

The US President and the North Korean leader greeted each other warmly before a row of US and North Korean flags, shaking hands and laughing eight months after their initial meeting in Singapore.

Trump hailed the friendship, saying the greatest achievement of his diplomatic gambit was the amicable way they've gotten along.

"I think the greatest progress is our relationship," he said, before praising the iron-fisted despot as a "great leader" who could see his country's economy blossom.

"I think your country has tremendous economic potential. Unbelievable. Unlimited," he said. "I think you will have a tremendous future with your country -- a great leader. And I look forward to watching it happen and helping it to happen."