Trump hailed what he called a "beautiful" letter he received from Kim.
Trump and Kim agreed at the first US-North Korea summit in Singapore to work towards the complete denuclearisation of the Korean peninsula, easing fears of war between their countries.
Trump's comments came as he continued to lavish praise on Kim Jong Un, who has aggressively pursued a nuclear weapons program while running a government accused of brutal human rights abuses, even after a breakdown in their nuclear talks earlier this year in Vietnam. "Kim Jong Nam likely had enough personal, intimate, and family information in his head to warrant an approach from CIA - or any intelligence agency - for debriefing purposes", said Darrell M. Blocker, a longtime CIA operative and now an ABC News contributor. "I wouldn't let that happen under my auspices", Trump said.
Moon Chung-in, the presidential special adviser for unification and national security, said in Seoul Wednesday that Kim's letter to Trump "could open up new possibilities" between the North and the United States following the "setbacks" since the Hanoi summit.
Earlier Tuesday, Bolton had told the Wall Street Journal at an event in Washington that North Korea is not complying with the terms agreed upon during Trump's first summit with Kim, in Singapore a year ago. There's no nuclear testing, there's no large, you know, long-range missiles going up.
"On the day he was killed, he was found with $120,000 in cash in his little backpack and so that may have been as a payment for his services", she said.
That, according to the Wall Street Journal report, would have limited his value as a source of intelligence.
Tensions have risen again recently, as North Korea resumed some limited testing of weapons and warned of "truly undesired consequences" if the U.S. was not more flexible.
Reuters has also reported that Russian tankers had supplied fuel to North Korea by transferring cargoes at sea.
Q: Any plan, any thought, about another meeting with Kim Jong Un?
"The book says that security camera footage from Kim Jong Nam's last trip to Malaysia showed him in a hotel elevator with an Asian-looking man who was reported to be a USA intelligence agent", Reuter noted.
On February 13, 2017, when Kim Jong-nam appeared at a check-in counter at a Kuala Lumpur airport terminal in Malaysia, he was jumped by two women who smeared something on his face.
Trump also addressed Tuesday a recent report that the North Korean leader's half brother Kim Jong-nam had been a Central Intelligence Agency informant. In February, Trump walked out of his second round of meetings with Kim without reaching an agreement.