"This is a great first step in terms of bringing a bunch of fallen Americans home", said Rear Admiral Jon Kreitz, the deputy director of the agency in charge of identifying the remains, the Defense POW/MIA Accounting Agency (DPAA).
US spy agencies are seeing signs that North Korea is constructing new missiles at a factory that produced the country's first intercontinental ballistic missiles capable of reaching the United States, according to officials familiar with the intelligence.
The U.S. -led United Nations Command planned a formal repatriation ceremony Wednesday at Osan, where the remains have been examined and catalogued by DPAA.
After a solemn ceremony at the US military's Osan Air Base in South Korea, 55 boxes of remains draped in the United Nations flag were taken to a USA military plane, which will then take them to a military laboratory in Hawaii for further analysis and identification.
"We don't know who's in those boxes, " Secretary of Defense Jim Mattis told reporters Friday at the Pentagon.
One leading expert on North Korea's missile program agrees. "We have lots of work to do".
"This is an worldwide effort to bring closure", Mattis said.
Friday's transfer of the remains coincided with the 65th anniversary of the 1953 armistice that ended fighting between North Korean and Chinese forces and South Korean and US -led forces under the U.N. Command.
Members of support group the Korean War Prisoners Of War and Missing In Action Network have told families to be cautious about the latest releases, saying they could be from other nationalities, not necessarily American.
The remains will undergo a lengthy forensics process at the military lab, which is staffed by more than 30 anthropologists, archaeologists and forensic odontologists. The Post stressed that this does not prove that the country is expanding its nuclear program, but it does show that it has continued to work on its advanced weapons.
An armistice that ended the Korean War has yet to be replaced with a peace treaty, leaving the peninsula in a technical state of war. That could then allow the North to demand the pullout of 28,500 USA troops deployed in South Korea.
"Just over 1,000 men are unrecovered" from the so-called Demilitarized Zone and nearby buffer zones, according to DPAA.
If North Korea's Kim Jong Un wants to attend the 2018 Asian Games, he need not worry, according to Indonesian envoys in Pyongyang this week.
It also comes despite U.S. President Donald Trump's claim on Twitter, shortly after his landmark summit with North Korean leader Kim Jong Un in Singapore, that Pyongyang was "no longer a Nuclear Threat".
USA spy satellites have detected renewed activity at the North Korean factory that produced the country's first intercontinental ballistic missiles capable of reaching the United States, according to a senior US official.
Satellite photos reportedly show that North Korea continues work on developing intercontinental missile technology.