The remains were recovered in North Korea between 1996 and 2005, at a time when Pyongyang allowed US and South Korean scientists to explore battle sites from the 1950-1953 conflict.

The Pentagon's Defense POW/MIA Accounting Agency, which has a large lab in Hawaii, said that its scientists had worked with South Korean counterparts in a joint forensic review over the past month.

"Working cooperatively and thoroughly, they concluded that the 64 individual remains are of South Korean origin, though the remains haven't been individually identified," the DPAA said in a statement.

The remains will be handed over to South Korea during a ceremony at Pearl Harbor in Hawaii later Thursday.

The US last returned 12 sets of South Korean remains in 2012, during a repatriation ceremony.

In July, Pyongyang returned 55 cases of US remains, in line with an agreement between Trump and North Korean leader Kim Jong Un at their summit in Singapore in June.