The repatriation is part of the June summit agreement between US President Donald Trump and North Korean leader Kim Jong-un, which also includes seeking to build "new" ties, foster a "lasting and stable" peace regime and pursue the complete denuclearization of the peninsula.

"The Korean War fallen have never been forgotten by the United States of America nor the 16 other sending states that comprise the UNC. UNC never leaves troops behind, living or deceased, and will continue the mission of repatriation until every service member returns home," the command said in a press kit.

"UNC is taking great responsibility to ensure remains from the Korean War are being handled with dignity and are properly accounted for so their families may receive them in an honorable manner," it added.

The ceremony will be attended by 500 people, including South Korea's Defense Minister Song Young-moo, UNC commander Gen. Vincent Brooks and US Ambassador to Seoul Harry Harris.

Upon return from the communist state on Friday, the remains were examined and catalogued at Osan Air Base by the Defense POW/MIA Accounting Agency until Tuesday. POW stands for Prisoners of War and MIA means Missing in Action.

Following the repatriation ceremony, the remains will be flown to a DPAA laboratory at Joint Base Pearl Harbor-Hickam in Hawaii, where historians and scientists will work for forensic identification, the command said.

At the DPAA lab, staffed by more than 30 anthropologists, archaeologists and forensic odontologists, the remains are examined to produce a biological profile that includes sex, race and age at death. Scientists use various techniques, such as analysis of skeletal remains and sampling mitochondrial DNA. They also analyze material evidence, including uniforms, personal affects and identification tags.

When the identification process is complete, the remains will be returned to their next of kin for burial.

Since 1990, an estimated 629 sets of US war remains have been recovered, according to the UNC.

The US estimates that some 7,630 sets of remains, including about 1,000 in the Demilitarized Zone, are in the North.

The repatriation event comes amid growing concerns about a lack of progress in the North's denuclearization efforts.

Washington and Pyongyang appear to be at loggerheads over the sequence of what could be a long peace process.

The North wants the US to agree to a political declaration of a formal end to the Korean War in an apparent move to ensure its regime security, while the US apparently wants the communist state to take concrete denuclearization steps first, including an accurate declaration of its nuclear and missile programs. (Yonhap)