Up to 1.5 million communist forces are thought to have died in the 1950-1953 Korean War.
About 30,000 US, 400,000 South Korean, and 1,000 UK troops, among others, also died, as well as at least two million civilian.
Tens of thousands more are listed as missing and both Koreas still conduct searches for soldiers' remains, periodically returning the foreign soldier's remains.
The remains of nearly 800 North Korean soldiers, however, have not been returned, such is the animosity between Seoul and Pyongyang, our correspondent says.
The Korean War ended with an armistice agreement. A formal peace treaty has never been signed and the two Koreas remain technically at war