In essence, the whole peninsula is disputed, as both the North and the South theoretically seek reunification upon their own ideological lines: neoliberal social democracy for the South and a militant communism for the North. But reunification has become an increasingly distant dream over the past half century as the systems have become fully entrenched in their respective spheres. On a more immediate basis, tension between the two countries centres around their border onshore, the Demilitarized Zone (DMZ), and their UN-designed maritime border, the Northern Limit Line (NLL).
It was divided into Soviet and American occupied zones along the 38th parallel, when the Japanese were forced to relinquish control at the end of World War II. UN-supervised elections were held in the south in 1948, but when the North refused to participate, separate governments were created for each area.
In the ceasefire of 1953, the DMZ was created, when each side agreed to move their troops back 2km from what had been the front line, creating a buffer zone 4km wide. The Military Demarcation Line (MDL) indicates exactly where the front was when the agreement was signed.
The MDL was extended into the sea by the US-led UN military forces after the ceasefire, and this Northern Limit Line now serves as the de facto maritime boundary. The 1953 Armistice Agreement specified that the UN Command (ie South Korea) would retain control of five islands, including Yeonpyeong and Baengnyeong Islands. The NLL was not part of the actual Armistice Agreement because the two sides could not agree how the territorial sea should be measured: the UN favoured three nautical miles, while the North favoured 12. The NLL, unsurprisingly, adopts the UN preferred option.
While both sides acknowledge the DMZ as the border between the two, the North does not accept the NLL, and since 1999 has been arguing in favour of a more southerly ‘West Sea Military Demarcation’.
The dispute between the two Korea’s is very serious, not only for the people living on the peninsula, but because any dispute between the two threatens to involve their international backers: the US for the South and China for the North.
Since the 1950s the tension on the peninsula has remained high and there have been numerous border clashes. A series of low-level armed clashes around the DMZ area between 1966-69 has been called the Second Korean War by some; there have been numerous assassination attempts on South Korean presidents by the North; and the North has dug at least four tunnels crossing under the DMZ in what appears to be preparation for a military strike. The North claims that they are for coal mining, and the walls have been painted black to give the appearance of coal.
The South, and their American allies are not innocent either, and there have been numerous incidents of American helicopters and other aircrafts invading northern airspace. They have been shot down on at least two occasions.
There have been political wrangling as well as military, including the bizarre 'flagpole war' of the 1980s. The South Korean government installed a 98.4m tall flagpole with a 130kg South Korean flag in Daeseong-dong, a South Korean town that lies within the DMZ. In retaliation, the North promptly built what was then the tallest flatpole in the world at 160m, with a 270kg North Korean flag, near Panmunjom, the town on the MDL where the Armistice talks took place in 1953.
Also on the MDL is the Joint Security Area (JSA), where all negotations since 1953 have taken place. Amusingly, the area has been built so that the MDL goes through conference rooms, and even down the middle of conference tables, so North and South Koreans can meet face to face while remaining on their own jurisdiction.
The NLL has also been the cause of numerous disputes. The fact that it enforces a 3 nautical mile territorial sea has prevented the North from accessing its rightful Exclusive Economic Zone (EEZ), as dictated under the UN Convention on the Law of the Sea. As a result, the North does not recognise the line, and its fishing boats consistently work close to, or over, the limit line, often escorted by North Korean naval boats.
What has happened in recent years?
Relations began to improve in the early 1990s, with the 1991 'Agreement on Reconciliation, Nonaggression and Exchanges and Cooperation between the South and the North' (also known as the ‘Basic Agreement’) which acknowledged that reunification was the goal of both governments, and the 1992 'Joint Declaration of the Denuclearization of the Korean Peninsula'.