The United States and North Korea on Friday put forward starkly different accounts over the breakdown of a high-stakes summit in Hanoi, with Pyongyang warning it would not put more on the table.

After weeks of building expectations and with a signing ceremony ready to go, President Donald Trump abruptly ended his second-ever meeting with North Korean leader Kim Jong Un and declared a deadlock.

"Sometimes you have to walk and this was just one of those times," an unusually downbeat Trump told reporters.

"Basically they wanted the sanctions lifted in their entirety and we couldn't do that," Trump said before flying back to Washington.

But in an exceptionally rare meeting with reporters, North Korean Foreign Minister Ri Yong Ho summoned the press in Hanoi at midnight and denied the White House account that Pyongyang was only seeking a complete deal.

North Korea had offered to "permanently and completely dismantle all the nuclear production facilities" at its main complex in Yongbyon if the US dropped sanctions "that hamper the civilian economy and the livelihood of our people", Ri said.

He warned that the North's stance was "invariable" and that its offer will "never change", even if the US proposes more negotiations in the future.

The North Koreans appeared to be looking to make their case to the world after Trump insisted that he could obtain a better deal.

"I'd much rather do it right than do it fast," Trump told reporters, reaffirming his "close relationship" with Kim.

"There's a warmth that we have and I hope that stays, I think it will."

White House spokeswoman Sarah Sanders told reporters on Air Force One that Trump was aware of Ri's comments but offered no further clarification.

– 'It will take a little while' –

The outcome in Hanoi fell far short of the pre-meeting expectations and hopes, after critics said the initial historic meeting in Singapore between the two leaders was more style over substance.

At that meeting, Kim and Trump signed a vague document in which Kim pledged to "work toward complete denuclearisation of the Korean peninsula". Progress subsequently stalled, with the two sides disagreeing on what that means.

The US president, who touted his "special relationship" with Kim, has since frequently dangled the prospect of a brighter economic future for a nuclear-free North Korea, at one point saying there was "AWESOME" potential.

But it was not enough.

The leaders walked away with no set plans for a third meeting, although Trump said he hopes to see Kim again soon.

US Secretary of State Mike Pompeo, who accompanied Trump, said both sides "need to regroup" before agreeing to another meeting, adding: "My sense is it will take a little while."

Pompeo however also said "there's still a basis for believing that we can move forward".

Beyond the sub-par summit result, Trump came under fire at home for saying that Kim "didn't know" about the torture of an American college student jailed in the North.

Otto Warmbier, who was arrested for allegedly taking down a poster, returned home in 2017 in a coma and died soon afterward, with a US judge ruling that the 22-year-old had died from torture.

House Speaker Nancy Pelosi said she thought there was "something wrong" with a US president choosing to believe "thugs" such as Kim and Russian President Vladimir Putin over the US intelligence community.

– 'Major failure' –

With a table already prepared for a working lunch and signing ceremony, Trump moved up his final news conference by two hours as he and Kim left without any accord.

"This is a major failure," tweeted Joe Cirincione, president of the Ploughshares Fund peace foundation, saying it showed the limits of top-level summitry with "not enough time or staff" to work out a deal.

Trump flew around the world for the meeting and Kim undertook a mammoth two-and-a-half-day trek through China in his olive green train, travelling 4,000 kilometres (2,500 miles).

Trump headed home, and Kim will stay on in Hanoi for a state visit.

The US leader placed calls from Air Force One to the leaders of US allies Japan and South Korea to discuss the summit, Sanders said.

Seoul said that Trump "expressed regret" to President Moon Jae-in, who helped arrange the summits, over not striking a deal with Kim.

Japanese Prime Minister Shinzo Abe, a longstanding hawk on North Korea, told reporters that he "fully supports President Trump's decision to make no easy compromise".

In China, North Korea's primary ally, foreign ministry spokesman Lu Kang voiced understanding, saying that "solving this problem is definitely not something that can be achieved overnight"

– 'Rocket man' –

As in Singapore, the two men put on a show of bonhomie in Vietnam, appearing to share jokes in front of reporters.

They even indulged in a poolside stroll Thursday around the gardens of the luxury Metropole Hotel.

It was a far cry from the height of missile-testing tensions in 2017 when Trump slammed Kim as "rocket man" and the younger man branded the American president a "mentally deranged US dotard".

Before the summit, there was talk that there could be a political declaration ending the 1950-53 Korean War, which finished technically with an armistice rather than a peace treaty.

Trump's failure to clinch a deal paradoxically brought him praise within his Republican Party — some members had privately fretted that he was too eager to seal a historic accord.

Senate Majority Leader Mitch McConnell said that Trump "should be commended for his personal commitment to persuading Kim Jong Un to pursue a different path — and for walking away when it became clear North Korea was not ready to commit enough to denuclearisation."

Fags and food: Five things we learned from the Hanoi summit
Hanoi (AFP) Feb 28, 2019 –

Cigarette breaks and poolside strolls: the world again saw a more human side to North Korean leader Kim Jong Un and US President Donald Trump as their unlikely diplomatic rapprochement endured for a second date.

But bonhomie and bromance are not always enough and the summit ended abruptly without an agreement, with sanctions proving a deal-breaker.

Here are five things we learned from the two-day gathering in Vietnam's capital Hanoi.

– Food for thought –

Hanoi was not a summit for anyone hoping to diet.

The US president was treated to a five-course lunch with the Vietnamese prime minister that included scallops, mango, spring rolls, cod, Wagyu beef, wood-ear mushrooms, lotus seeds and longans, a tropical fruit.

Perhaps understandably, the US side reportedly asked for a more "simple" dinner with Kim and backroom staff were said to be wrangling over the menu until the last minute.

In the end, the 80s classic of prawn cocktail, avocado and thousand island dressing kicked off the meal, followed by a fusion of styles for the main: grilled sirloin with a kimchi-stuffed pear. A runny chocolate "lava" closed it out.

The following day's working lunch was abruptly cancelled but for the record, the menu showed they were due to eat snow fish – a deliciously tender Asian species – apple foie gras jelly and banoffee pie. In the event, the empty table settings spoke volumes.

– Trains, planes and automobiles –

For their first historic meeting in Singapore, Kim borrowed a plane from his Chinese friends but this time, he undertook a mammoth 4,000-kilometre (2,500-mile) rail journey in his olive green train.

Footage of him taking a cigarette break at a brief stopover in China lit up social media, his ever-present sister Kim Yo Jong rushing to his side to hand him an ashtray.

And to complete the set, automobiles played another role in this summit.

In Singapore, Trump set Secret Service hearts pounding by allowing Kim a glimpse into his top-secret armoured "Beast".

This time, a senior North Korean delegation was given a guided tour around a Vietnamese car factory touted as a model for Pyongyang's potential economic development.

– Vox pop Kim –

At home, Pyongyang carefully choreographs Kim's every appearance in its tightly-controlled media, with state television often not even broadcasting natural sound from his events.

And while foreign journalists have tried before to draw an unscripted response from the reclusive leader, no one had ever been successful before.

So it must have come as quite a surprise to the Washington Post reporter who dutifully asked Kim if he was confident he could reach a deal with Trump, when he actually answered.

The North Korean went on to answer several more shouted questions at media opportunities — but analysts warned against interpreting it as some new openness on Pyongyang's part.

In fact, a double booking snafu had already revealed the North Koreans' reticence about close proximity to reporters. The White House set up a media centre for its press corps in Kim's hotel, but the journalists were then unceremoniously ejected.

– Sister in shot –

Kim's sister Kim Yo Jong rarely leaves her brother's side, to the extent she has several times accidentally found herself in shot when the world's cameras are trained on him.

At the inter-Korean summit last April, she wildly swerved off to the side of the red carpet when she realised she was in her brother's limelight.

This time, as Trump and Kim took a poolside stroll at the luxury Metropole Hotel in Hanoi, she tried to make sure she was not the focus by hiding behind a tree — but was still clearly visible peeping through the leaves.

– What about North Korea? –

After the summit abruptly ended without a deal, the world's media scrambled to Trump's press conference to learn what the US president thought.

But Trump has a constant ability to surprise and he began not by talking about the past two days in Hanoi, but doing a tour of some of the rest of the world's hot spots — including Venezuela, and India and Pakistan.

In contrast to his wide-ranging and lengthy news conference in Singapore, a jaded looking president wrapped up well within the hour with the parting shot: "That's it ladies and gentlemen. I'm about to get on a plane and fly back to a wonderful place called Washington DC."

His unenthusiastic tone belied the reality: aftershocks from his former lawyer's testimony are waiting for him at home.