DECADES after the end of the Korean War, the remains of dozens of presumed US war dead have begun their journey home following a ceremony in South Korea.

North Korea handed over the remains in 55 boxes last week, but included just one military dog tag.

A US military transport plane to was then allowed to move them to the US Osan Air Base near Seoul in South Korea.

While it was an apparent goodwill gesture by North Korea towards the United States, the return comes amid growing scepticism about whether the North will follow through on its pledge of nuclear disarmament.

Hundreds of US and South Korean troops gathered at a hangar at the Osan base for the repatriation ceremony before US and South Korean soldiers loaded the cases containing the remains one by one into transport planes.

The planes will fly them to Hawaii, where they will undergo an in-depth forensic analysis, in some cases using mitochondrial DNA profiles, at a Defence Department laboratory to establish identifications.

US defence secretary Jim Mattis said last week that the return of the 55 boxes was a positive step but not a guarantee the bones are American.

A US defence official said it will probably take months if not years to fully determine individual identities from the remains.

Vice-president Mike Pence, the son of a Korean War veteran, is to fly to Hawaii for what the military calls an “honorable carry ceremony” marking the arrival of the remains on American soil.

The repatriation is a breakthrough in a long-stalled US effort to obtain war remains from North Korea.

About 7700 US soldiers are listed as missing from the 1950-53 Korean War, and 5300 of the remains are believed to still be in North Korea.