Cultural Properties Not Being Returned

The government has revealed that Korean cultural properties currently abroad number about 68,000 items. So far only 5% or 3,777 items have been returned. This is just a fraction of Korean artifacts residing in foreign coutries because figures are based only on foreign national or municipal museums, and not private holdings.
The Ministry of Culture and Tourism announced on October 13 that Korean cultural assets, currently out of Korea, total 68,520 items in 18 countries. Japan has the most with 31,267 followed by the USA, England, Germany, and Russia.
The reason these properties are not being returned is that Japan concluded a treaty with Korea in 1965 that absolved past appropriations with each other thus legally blocking attempts to recover historical artifacts, artwork, pottery, etc. Other countries, which acquired Korean artifacts through various means, are also not joining in the UNESCO pact to return cultural property to their original nation.
These treasures were mainly taken out of Korea during times of Japanese invasions like the 1592 Imjin War, the Japanese colonial period that lasted the first half of this century, and the Korean War from 1950 to 1953.