Kim Jong-nam,the half-brother of North Korean dictator Kim Jong-un,pictured in 2010.Credit:AP
TheJournal cited an unnamed"person knowledgeable about the matter"for the report,and said many details of Kim Jong-nam's relationship with the CIA remained unclear.
Reuters could not independently confirm the story. The CIA declined to comment.
The Journal quoted the person as saying"There was a nexus"between the CIA and Kim Jong-nam.
"Several former US officials said the half brother,who had lived outside of North Korea for many years and had no known power base in Pyongyang,was unlikely to be able to provide details of the secretive country's inner workings,"theJournal said.
The former officials also said Kim Jong-nam had been almost certainly in contact with security services of other countries,particularly China's,theJournal said.
South Korean and US officials have said the North Korean authorities had ordered the assassination of Kim Jong-nam,who had been critical of his family's dynastic rule. Pyongyang has denied the allegation.
Two women were charged with poisoning Kim Jong-nam by smearing his face with liquid VX,a banned chemical weapon,at Kuala Lumpur airport in February 2017. Malaysia released Doan Thi Huong,who is Vietnamese,in May,and Indonesian Siti Aisyah in March.