Trump's comments came as he continued to lavish praise on Kim Jong Un, a global pariah due to his reclusive country's nuclear program and abysmal human rights record, even after a breakdown in their nuclear talks earlier this year in Vietnam. Trump, who said he had "just received a beautiful letter" from Kim, said Kim had kept his word in halting tests of nuclear weapons and long-range ballistic missiles.
On Tuesday, officials at South Korea's National Intelligence Service and Unification Ministry, which oversees ties with North Korea, said they couldn't confirm the report on Kim Jong Nam.
While Kim Jong Nam spent much of his life abroad after falling out of favor with his family, he was constantly aware of the monitoring presence of Pyongyang and obsessed by fears that he would get assassinated, South Korean officials have said. Following his death, the NIS told South Korean lawmakers that North Korea had tried for several years to kill him and that he sent a letter to Kim Jong Un in 2012 begging for the lives of himself and his family.
Kim Jong Nam was the eldest son in the current generation of North Korea's ruling family and could have been seen as a threat to Kim Jong Un's rule.
The Journal said Kim Jong Nam met on several occasions with CIA operatives, but also that many details of his relationship with the agency remain unclear.
Messages left with the CIA weren't immediately returned.
Kim Jong Nam was killed on Feb. 13, 2017, when two young women smeared VX nerve agent on his face at a Kuala Lumpur International Airport terminal.
Murder charges were dropped against the women earlier this year. They had been accused of colluding with four North Koreans who prosecutors said had fled the country the day of the attack.
Lawyers for the women have said they were pawns in a political assassination with clear links to the North Korean Embassy in Kuala Lumpur. The U.S. and South Korea also have blamed North Korea, but Malaysian officials never officially accused Pyongyang of involvement.