“It isn’t surprising that this broke down over the sequence magnitude of sanctions relief – North Korea has been saying it for months: full sanctions relief, not end of war, is what it views as a measure that must come before any further nuclear steps,” said Vipin Narang, a non-proliferation expert at Massachusetts Institute of Technology. “One can only paper over the differences for so long.”

But despite failing to sign a deal, Trump won plaudits from across the aisle for choosing to walk from the negotiating table rather than strike a weak agreement that would leave Kim’s nuclear programme largely undisturbed.

Some of his strongest critics had warned he could sign a flimsy accord to score a political win.

“No deal is better than a bad deal,” said David Kim, a researcher at the Stimson Center and a former State Department official in the Obama administration. “Reagan walked away from negotiations in Reykjavik but it ultimately turned out OK for him. Patience is a virtue.”

Even former US vice-president Joe Biden appeared to back Trump’s decision.

“The president did the right thing by walking away,” he reportedly said at a leadership forum in Nebraska on Thursday. But he warned: “Diplomacy matters, preparation matters.”

US-North Korea talks remain best way to achieve lasting peace

Kim’s departure from Hanoi with nothing from his wish list that included sanctions relief and a peace treaty to formally end the Korean war has heightened his domestic political risk – state media on Friday gave a positive spin to talks and suggested Kim and Trump would meet again.

“North Korea seemed to have miscalculated and came out of this with no progress towards sanctions relief and perhaps a tarnished reputation as a good-faith negotiator,” said Mintaro Oba, who worked in the US State Department during the Obama administration.

The collapse of the talks is likely to further cripple Pyongyang’s future ability to negotiate.

“People who had been sceptical of North Korea’s full denuclearisation commitment will have a stronger view on this,” said Li Mingjiang, a China specialist at Nanyang Technological University (NTU) in Singapore.

“Hawks in the US will gain an upper hand in decision-making. All these make it more difficult for North Korea to manoeuvre in its talks with the US in the future. The sanctions are unlikely to be loosened up in the near future. I would say this is a major loss for North Korea.”

China could be among the growing ranks of those increasingly frustrated with Pyongyang. Although it remains the North’s closest ally and top trading partner, Beijing has long called on its neighbour to reform, and has joined the international sanctions against the regime.

“China will be extremely disappointed because it was proven that North Korea is not on the same page, despite their fourth summit in Beijing in January,” said Jaewoo Choo, a professor in Chinese foreign policy at Kyung Hee University in Seoul. “Kim failed to give face to China who apparently was asked by Trump to mediate with Kim.”

Yun Sun, director of the China Program at the Stimson Center, said Beijing could see an upside in reasserting itself as mediator between Washington and Pyongyang.

“The good future is of course one where they continue to talk, and have China as the facilitator,” said Sun. “But Trump might feel diplomacy is not working for denuke and Kim might feel he gets nothing in return, so either or both of them could resume the hard line.”

Li from NTU said protracted negotiations between the sides could be to Beijing’s advantage.

“Washington may realise that it has to ask for China’s assistance and Pyongyang may constantly need Beijing’s support as well,” he said. “In this sense, China may have the opportunity to propose some policy suggestions and act as a mediator.”

Trump-Kim summit 2019: Xi could be ‘more helpful’

South Korea, a close US ally which hosts 28,500 American troops, may be among the biggest losers in Hanoi. The failure to make progress on denuclearisation is likely to derail President Moon Jae-in’s plans to resume stalled inter-Korean economic projects and host Kim on a historic visit to South Korea sometime later this year.

“Seoul will find it more difficult to persuade the Americans,” said Li. “And South Korea’s engagement policy towards the North will encounter greater pressures from Washington. The rift between Seoul and Washington may become wider.”

Said Kim Jong-ha, a security expert at Hannam University: “With high expectations comes great disappointment. Now South Korea faces a situation where it has to live with North Korea’s nuclear weapons.”

Moon Jae-in may be the biggest loser of the Trump-Kim summit flop

Japan, which views Pyongyang as its main security threat, appears to feel relief that Trump did not loosen the screws on the North for little in return.

“I fully support President Trump’s decision not to make the easy choice,” said Japanese Prime Minister Shinzo Abe on Thursday.

Abe, who has been largely isolated in the denuclearisation process so far, indicated his desire to take a more active role. “I am determined that I must meet Chairman Kim next,” he said, repeating his wish to sit down with the North Korean leader.