The meeting in Singapore offered a dramatic image makeover for Kim, previously known for his apocalyptic threats of nuclear war and accused of ordering the killings of his own uncle and half-brother.

During his three-day visit, a smiling Kim shared a historic handshake with Trump, took selfies with top Singaporean officials and toured the city-state's scenic waterfront, drawing throngs of onlookers.

Trump praised Kim as a "very talented man" who "loves his country very much," after ignoring a reporter's question on whether he raised the issue of Otto Warmbier -- a US student who died after being detained in the North for more than a year.

"Some say Kim is 'cute' or 'friendlier than expected,' but they should not be deceived by Kim's smiling face at this political show," Choi Jung-Hun, a North Korean defector living in Seoul, told AFP.

The Kim family has ruled the impoverished, nuclear-armed nation with a pervasive personality cult and little tolerance for dissent.

North Korea stands accused of a litany of state-sanctioned rights abuses including torture, rape, execution and brutal crackdowns on dissent.

The regime is estimated to have up to 120,000 political prisoners in its sprawling gulag system.

Kim also had his own powerful uncle, Jang Song-Thaek, executed in 2013 for treason, and is accused of ordering the assassination of his half-brother, Kim Jong Nam, at a Malaysian airport in 2017.

- 'Diplomatic reality show' -

Days before Tuesday's summit, more than 300 rights groups including Human Rights Watch urged Pyongyang to improve its dire rights records.

"Kim Jong Un is trying to become an international statesman, but this effort will fail if he continues to preside over a country that has been referred to as the 'world's biggest open prison'," said Brad Adams, Asia director at HRW.

Trump repeatedly suggested lifting sanctions on the North as ties improved, and praised Tuesday's summit as a "tremendous success".

But while many sanctions were imposed over the North's missile and nuclear weapons tests, some were imposed over rights abuses, John Sifton, HRW Asia advocacy director, said.

That means human rights would be "staying on the agenda of subsequent negotiations, whether they (Kim and Trump) want it or not" Sifton warned on Monday.

Amnesty International also urged efforts to shed light on the "near total denial of human rights" in the North at the summit.

"It would be deeply disappointing if the catastrophic human rights situation in North Korea is completely overlooked as diplomatic relations continue to thaw," it said last week.

The US State Department's latest rights report on the North, released earlier this year, describes "egregious human rights violations" in the authoritarian state, from public executions to widespread surveillance of citizens.

Trump acknowledged earlier this month that he had not raised the issue of human rights during the preparation stage for the summit but on Tuesday said it had been discussed.

Choi urged the international community to see the "dark side behind the diplomatic reality show".

"I really hoped that Trump raised the issue of human rights during the meeting with Kim... so that this dialogue would mean something even for poor North Koreans rotting in prison camps," he said.