The two leaders strolled through the hotel garden between talks sessions, echoing a break they took at their first summit in Singapore.

Unlike that occasion, this time they had their interpreters with them. They said little, although they looked relaxed.

And in the background, Kim's sister and close aide Yo Jong, who has displayed a repeated ability to appear in summit images of her brother in both Singapore and at inter-Korean meetings in Panmunjom, the truce village in the Demilitarized Zone that divides the peninsula.

She peered around a pillar, before lurking behind a large potted plant as the men stopped to chat, joined by a smiling US Secretary of State Mike Pompeo and Kim's righthand man Kim Yong Chol.

The group milled awkwardly around a table for a few minutes, seemingly unsure whether to sit down.

It was a sticky, overcast day in Hanoi and Trump at one point gestured toward the sky before the group was ushered into a swanky cafe inside the colonial-era hotel.

Built in 1901, the Metropole has hosted Angelina Jolie, Brad Pitt and Charlie Chaplin, who famously honeymooned there.

Beneath the 360-room hotel are Vietnam War-era bunkers where Hanoians once sought shelter from American bombs raining down on the city.

The convivial stroll was a world away from the war of words Kim and Trump engaged in during 2017, when the US president dubbed the North Korean a "rocket man" on a "suicide mission", with Kim calling him a "mentally deranged US dotard" in return.

Trump is a former reality television star, but Kim has also shown himself keenly aware of the optics of their summits.

"There are people who hold a sceptical view of our meeting," he said Thursday, sitting alongside Trump.

"And for them, I think watching us have a great time will be like watching a scene from a fantasy movie."

It was another echo from Singapore, when Kim mused to Trump that viewers would see the spectacle as a "fantasy ... from a science fiction movie".