This article is a good and fair summary of the current situation with the Liancourt Rocks dispute, but it seems to be trying too hard not to offend either Japan or South Korea. Fortunately, I do not have to worry about that.
The reason Korea refuses to take the Liancourt Rocks dispute to the International Court of Justice is that Korea knows it has little to no evidence to support its historical claim to the Rocks and that Japan has a great deal of evidence to support hers. Moreover, the 1951 Treaty of Peace with Japan recognized Japan's claim to the Rocks by not including them among the territories to which Japan gave up claim, as was confirmed in a Top Secret, 1954 report by President Eisenhower's Special Ambassador to the Far East, General James Alward Van Fleet, in which the General wrote the following:
"The Island of Dokto (otherwise called Liancourt and Take Shima) is in the Sea of Japan approximately midway between Korea and Honshu (131.80E, 36.20N). This Island is, in fact, only a group of barren, uninhabited rocks. When the Treaty of Peace with Japan was being drafted, the Republic of Korea asserted its claims to Dokto but the United States concluded that they remained under Japanese sovereignty and the Island was not included among the Islands that Japan released from its ownership under the Peace Treaty. The Republic of Korea has been confidentially informed of the United States position regarding the islands but our position has not been made public."The South Korean claim that there is no dispute with Japan over Liancourt Rocks is ridiculous, especially when the South Korean government has been refusing to meet with Japanese officials because Japan publicly claims the Rocks.
South Korea currently occupies Liancourt Rocks and knows that Japan will not use military force to retake the them, so why is South Korea making such a fuss over the Rocks and using the dispute as an excuse not to improve diplomatic and military cooperation with Japan? That is the question the United States should be asking itself and South Korea. The answer may be that South Korea wants to keep its options open with both China and the United States.
By feigning outrage with Japan over Liancourt Rocks, South Korea may be hoping to ease Chinese concerns of a possible South Korea-Japan military alliance while also using the dispute as an excuse for rejecting US requests to form a closer alliance with Japan. In other words, Korea seems to be using its old strategy of trying to remain neutral by playing off against great powers. I think South Korea should reconsider such a strategy, especially since it did not work last time.