(AFP) - Steadily, almost warily, the two leaders approached each other on a colonnaded verandah, their hands outstretched as a gaggle of media watched from a platform and the rest of the world looked on.

Weeks in the making after decades of war, antagonism and venom, the first encounter between North Korean leader Kim Jong Un and Donald Trump was a crucial moment.

Within the first minute in Singapore, the US president had proclaimed, he would know whether a deal over the North's nuclear arsenal was possible.

The drive to the venue took both men through the tourist enclave of Sentosa island and past the towers of Shrek's castle at a Universal Studios theme park.

But they emerged from their limousines grim and unsmiling, and the first few moments of their meeting appeared uneasy.

As the two shook hands for around 13 seconds, Trump reached out to touch Kim's shoulder, looking down at the shorter man as he spoke.

The two turned to face the cameras in front of a dozen American and North Korean flags, upright and unsmiling.

But as Trump ushered the North Korean towards their meeting room, Kim's lips creased into the beginnings of a smile, and the two men visibly relaxed the moment they turned off the stage at the Capella Hotel.

They chatted and smiled as they went into the first-ever one-on-one encounter between a leader of the North and a sitting US president.

The first minute of the meeting, Trump said, had felt "really great".

"I think it's going to be really successful and I think we will have a terrific relationship, I have no doubt."

- 'Not easy' -

Held on a former British military base, the summit came 65 years after Pyongyang's Chinese-backed forces fought the US-led UN coalition to a standstill in the Korean War, and followed years of increasing tensions over the North's banned nuclear and ballistic weapons programmes.

According to the South Korean news agency Yonhap, it was the first time the US and North Korean emblems had been officially displayed side-by-side since the New York Philharmonic played a concert in Pyongyang in 2008.

In Seoul, South Korean President Moon Jae-in -- whose country remains technically at war with the North -- watched live ahead of a cabinet meeting.

"I, too, could hardly sleep last night," he told his ministers, hoping for a "new era among the two Koreas and the United States".

Sitting across from Trump at a small side table, Kim told the US president through a translator: "It was not easy to get here.

"The past worked as fetters on our limbs and the old prejudices and practices worked as obstacles on our way forward," he went on, his listener looking him in the eye and nodding. "But we overcame all of them and we are here today."

Trump responded "That's true," before another handshake -- smiling this time -- and a thumbs-up from the US president.

© Agence France-Presse