A US military aircraft flew the remains of more than 50 American servicemen out of North Korea on Friday, prompting a personal "thank you" from Donald Trump to Kim Jong Un.
The return of the remains -- on the 65th anniversary of the end of the Korean War -- marks the partial fulfilment of an agreement reached between the US president and North Korea's leader at their historic summit in Singapore last month.
"After so many years, this will be a great moment for so many families. Thank you to Kim Jong Un," Trump said in a tweet.
The White House said it was "encouraged" by the return of the remains and the "momentum for positive change".
"Today's actions represent a significant first step to recommence the repatriation of remains from North Korea and to resume field operations in North Korea to search for the estimated 5,300 Americans who have not yet returned home," it said.
After leaving the North Korean port city of Wonsan, the C-17 cargo plane landed at the Osan US Air Base in South Korea, where American soldiers stood in ceremonial ranks.
The plane -- which had 55 sets of remains on board, according to the United Nations Command (UNC) in South Korea -- came to a halt next to a group of 10 honour guards carrying the flags of the UN, the US and South Korea.
After the rear door was opened, other uniformed guards went aboard and re-emerged each carrying in their arms a box draped in a white-and-blue UN flag.
They then slowly walked to awaiting vans, put the boxes in the vehicles and saluted, before the vans left the scene.
"It was a successful mission following extensive coordination," General Vincent Brooks, commander of the UNC and United States Forces Korea, said in a statement.
"Now, we will prepare to honour our fallen before they continue on their journey home."
More than 35,000 Americans were killed on the Korean Peninsula during the war, out of which around 7,700 are still considered missing, including 5,300 in North Korea alone, according to the Pentagon.
Between 1990 and 2005, 229 sets of remains from the North were repatriated, but those operations were suspended when ties deteriorated over Pyongyang's nuclear weapons programme.
The remains flown to Osan on Friday are expected to be sent to Hawaii for forensic identification, following a formal repatriation ceremony next Wednesday.
Trump has hailed his summit agreement with Kim as effectively ending the North Korean nuclear threat, although it contained only an ill-defined commitment on Pyongyang's part to the "denuclearisation of the Korean peninsula" -- a long way from the complete, verifiable and irreversible disarmament demanded by Washington.
The issue of repatriating remains of American war dead was seen as a far less contentious one, and the summit agreement specified the immediate return of those remains "already identified."
According to US officials, North Korea is estimated to have as many as 200 sets of remains ready for delivery.
Former New Mexico governor Bill Richardson, who has worked on repatriation issues and visited North Korea several times, warned that Pyongyang might hold up further repatriations in order to squeeze some cash out of the United States.
"They'll give a certain amount of remains for free right away," Richardson told the Washington Post. "But then they'll say, 'The next ones, we need to find them, locate them, restore them.' And then they'll start charging, and they'll milk this."
The initial repatriation provides the White House with a tangible result from the Singapore summit, which has otherwise failed to deliver on the denuclearisation expectations raised by the US president.
US Secretary of State Mike Pompeo was despatched to Pyongyang in early July to nail down the North's summit commitments -- including returning the remains of US servicemen.
Pompeo described the talks as "constructive" but the North Korean foreign ministry condemned his "gangster-like" demands for rapid nuclear disarmament.