North Korean leader Kim Jong Un has ordered his aides to "re-explain" to Tokyo the findings of a probe into the whereabouts of missing Japanese nationals suspected to have been abducted by Pyongyang decades ago, according to a South Korean activist.

Kim gave the directive after his historic summit with U.S. President Donald Trump in Singapore last month, said Choi Sung-yong, head of a group representing families of South Koreans abducted by North Korea, citing an informed source in the North's capital.

This would signal a shift in tone from Pyongyang's previous unwillingness to open up dialogue with Tokyo — which has been somewhat sidelined amid the flurry of diplomacy over North Korea's nuclear program, resulting in a recent thaw in relations between the North and the United States.