<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Korean reunification (Korean: 한국 의 재통일) refers to the potential reunification of the Democratic People's Republic of Korea (commonly known as North Korea), the Republic of Korea (commonly known as South Korea), and the Korean Demilitarized Zone under a single government . The process towards such a merger was started by the June 15th North--South Joint Declaration in June 2000, where the two countries agreed to work towards a peaceful reunification in the future . However, the process of reunification has met many difficulties due to ongoing tension between the two states, which have become politically and economically different since their separation in the 1940s . </P> <P> The current division of the Korean Peninsula is the result of decisions taken at the end of World War II . In 1910, the Empire of Japan annexed Korea, and ruled over it until its defeat in World War II . The Korean independence agreement officially occurred on 1 December 1943, when the United States, China, and Great Britain signed the Cairo Declaration, which stated: "The aforesaid three powers, mindful of the enslavement of the people of Korea, are determined that in due course Korea shall become free and independent". In 1945, the United Nations developed plans for trusteeship administration of Korea . </P>

What was built in an effort of cooperation between north and south korea