Cases of co-mingled remains are the most hard because they require identifying which skeletal fragments belong to the same person, said Luis Fondebrider, president of the Argentine Forensic Anthropology Team, a non-governmental group that applies forensic science to investigate human rights violations.
While North Korea razed both its only known nuclear testing site in Punggye-ri and the Iha-ri Driver Training and Test Facility in May, leading monitor 38 North noted on Thursday that "commercial satellite imagery of North Korea's Sohae Satellite Launching Station from June 12 shows no apparent activity related to dismantlement of its rocket engine test stand" and said last week that it "has not yet identified any activity associated with the dismantlement of facilities at Sohae or any other test sites in North Korea". Last week, he said the North's nuclear program no longer constitutes a danger following his summit with Kim in Singapore.
A USA official familiar with the process said the remains could be co-mingled - meaning not separated by individual - and could include people who were not American. Even if, implausibly, U.S.
US President Donald Trump on Friday extended the national emergency against North Korea by another year, asserting that the reclusive nation continued to pose an "unusual and extraordinary" threat to the US' national security, foreign policy and economy.
In the joint statement, Kim "reaffirmed his firm and unwavering commitment to complete denuclearisation of the Korean Peninsula", but made no reference to a timeline.
The Trump administration on Friday issued a routine notice to Congress describing the threat as reasoning for keeping sanctions in place on North Korea. "It creates both a hedge against relations with the USA going sour, and opens doors to economic activity back up".
The suspension of the exercises was regarded as a major win for Pyongyang as well as for regional superpower and North Korea ally, China.
Trump has often criticized his predecessors' handling of USA foreign policy, including the nuclear crisis with North Korea.
Trump lavished praise on Kim, which critics said downplayed the dictator's poor human rights record and lent him undeserved legitimacy on the world stage.
FILE PHOTO: Caskets that contain the remains of U.S. soldiers from the Korean War that were discovered in and repatriated from North Korea arrive at Hickam Air Force Base in Honolulu, Hawaii, U.S. April 12, 2007.
The order appears to undermine the president's claim.
Trump said on Wednesday the remains of 200 American servicemen had already been sent back, following on from the agreement he reached with Kim in Singapore.
About 100 wooden transport cases are being sent to the Demilitarized Zone, starting Saturday, to prepare for receiving US troop remains from North Korea, a representative for US Forces Korea said.