The defectors, who now live in Seoul, chatted and laughed at the office of North Korea Free Radio as they awaited news from the US president and the leader of their former homeland.

But they quickly fell silent as it became clear the talks were deadlocked.

Cha Ri-hyuk, 33, told AFP at the radio station -- which is staffed by defectors and broadcasts into North Korea -- that he was not shocked by the no deal outcome.

"I knew that Kim Jong Un would never give up the nukes. If the two countries were to make an agreement, I think they would have done it in Singapore last year," added Cha, who left North Korea in 2013.

Jo Young-hwa, aged 39, who defected a year earlier, said his countrymen "don't care" about the summits.

"Whenever I talk to them in the North, they are not interested. They don't bother trying to learn anything about it," he said.

"If you say something 'wrong' you can be prosecuted. You are being monitored by so many people all the time."

The no deal outcome will come as a huge disappointment for South Korea's president, who had touted the summit as a "remarkable breakthrough" for peace negotiations on the Korean peninsula.

His presidential office said earlier this week it had hopes Trump and Kim would formally declare an end to the 1950-53 Korean War.

Big questions now face the dovish leader, who was set to unveil details of a new economic cooperation policy between the two Koreas on Friday.

In Seoul's main railway station, dozens of people of all ages were glued to TV screens, sombre faced as Trump explained why he and Kim had failed to reach an agreement.

Some expressed sympathy for the North Korean leader.

"I feel bad for Kim Jong Un who made a very long train journey to get to Hanoi only to walk away from the meeting with empty hands," said Jang Ho-su, 36, a government employee.

Lee Gap-yong, a 71-year-old a taxi driver, said Trump could have been "more flexible".

"I think he wanted too much out of Kim, to an extent that Kim could not agree to."

South Korea's presidential office expressed regret at the summit's outcome but said "meaningful progress" had been made.