South Korea occupies the rocky and remote islands of Dokdo, but Japan calls them Takeshima and claims they are an integral part of its territory. As neither side is backing down, relations continue to deteriorate.
The discovery of a map drawn in 1861 may reignite a simmering territorial row between South Korea and Japan, and further damage bilateral relations that are already strained. The map was drawn by Korean cartographer and geologist Kim Jeong-ho and clearly marks the rocky islets that are known in South Korea today as Dokdo as being part of the kingdom of Korea.
The map covers the Korean Peninsula and has Dokdo close to the island of Ulleung, off the east coast. Japan, however, has long disputed South Korean control over the inhospitable islands and insists they are an integral part of the Japanese archipelago. Tokyo says the islands should be known as Takeshima.
Ironically, the map was in the collection of a Japanese national and had previously been in a library in Pyongyang. Serial numbers on the map show the date that it was obtained - August 30, 1932, when Japan was the colonial master of the peninsula - but little is known about its whereabouts in the intervening years.
Japan has long disputed South Korean control over the inhospitable islands and insists they are an integral part of the Japanese archipelago
Hailed as more proof
The discovery has been reported in South Korean media and hailed as yet another piece of evidence that Dokdo - which have a detachment of armed police permanently stationed on them - are sovereign Korean territory.
"All Koreans know that the islands are Korean and we are committed to protecting them," said Song Young-chae, a professor in the Center for Global Creation and Collaboration at Seoul's Sangmyung University. "There have been songs written about Dokdo and they have appeared on postage stamps, so they are constantly in our minds as being Korean," he told DW.
"The Japanese claims to the islands have no basis in historic fact and we find it stunning that they continue to claim the islands as theirs," he added.
According to Seoul's position on Dokdo, they only came under the control of Tokyo when Imperial Japan invaded the Korean Peninsula in 1910. The islands were then ceded to Shimane Prefecture, the closest part of mainland Japan, until Japan was defeated in World War II and surrendered in August 1945.
The fine print of the San Francisco Peace Treaty of 1951 now becomes important in the dispute. South Korea says that early drafts of the agreement included Dokdo among the thousands of islands and parcels of territory that had been seized by Japan and were to be returned to their historic owners across Asia.
By the sixth draft of the agreement, however, all the place names had become so cumbersome that for the sake of convenience only three major Korean islands were identified by name.
And Seoul believes if the islands were being returned to their historic owners, then they are clearly Korean.
Supporting South Korea's claims are ancient descriptions of the islands being part of the Silla Dynasty in 512 AD as well as maps and documents - Korean, Japanese and those made by Western explorers - amassed by the Seoul-based Northeast Asian History Foundation.
Arguably the most persuasive piece of evidence is a map produced as late as 1877 by Japan's Department of the Interior and which is held at the National Archives in Tokyo. The document shows that in a reply to a letter from the department to Japan's Great Council of State in March of that year, the council made it clear that Japan had no relationship with Dokdo.
But in Tokyo, the government now brushes aside Seoul's claims and insists that the islands are an inherent part of Japanese territory, based entirely on historical facts and international law.
An extensive section on the website of the Japanese foreign ministry states, "The Republic of Korea has been occupying Takeshima with no basis in international law. Any measures the Republic of Korea takes regarding Takeshima based on such illegal occupation have no legal justification.
"Japan will continue to seek the settlement of the dispute over territorial sovereignty over Takeshima on the basis of international law in a calm and peaceful manner," it adds.
To support its claim, Japan has proposed that the dispute be taken to the International Court of Justice in The Hague and that both sides be given the chance to stake their claims to the islands. Seoul has so far refused.
Demands that South Korea return the islands to Japanese control are most vociferous in Shimane Prefecture, which is 211 kilometers to the south.
On February 22 every year, the prefecture marks Takeshima Day with a series of events that invariably attract nationalist politicians from Tokyo and, equally inevitably, attract criticism from South Korea.
Hiromichi Moteki, acting chairman of the rightwing Society for the Dissemination of Historical Fact, says the growing animosity toward Japan demonstrated by the administration of South Korean President Moon Jae-in is "not a normal human attitude."
"I am not an expert on maps and I believe that careful analysis needs to be carried out to determine the accuracy of this newly discovered map," he said, but added that there has been a concerted campaign against Japan by the South Korean leadership that threatens to further harm the bilateral relationship.
On February 22 every year, the Shimane Prefecture marks Takeshima Day with a series of events that invariably attract both nationalist politicians from Tokyo as well as criticism from South Korea
One of the biggest areas of contention is the agreement signed in 2015 by the leaders of Japan that was designed to draw a final line under the issue of "comfort women," the women in occupied countries forced to work in brothels for Japanese troops.
Since his election in May, Moon has overseen the creation of a panel to look into scrapping the agreement. "I would say that at present, this is the worst two-way relationship between Japan and South Korea that I have ever experienced," said Moteki. "And this map could make things even worse. I hope things will improve, but I fear that they will only get worse."