East Sea

Historically, the sea area between the Korean Peninsula and the Japanese Archipelago, known as the 'Sea of Japan', had been referred to by various names. Even though no single name had been consistently used to designate this body of water until the 19th century, designations containing references to Korea were predominantly found on maps. It's worthy of note that as late as 1870 even many Japanese map referred to this body of water as the 'Sea of Chosun(Korea)' instead of 'Sea of Japan.'
It was not until the Russo-Japanese War (1904-1905) that the term “Sea of Japan” gained wider acceptance. The active promotion by Japan and its enhanced political stature in the world scene during the first half of the 20th century led to the gradual replacement of such names as “Sea of Korea”, “East Sea”, or “Oriental Sea” with the term “Sea of Japan.”
This process culminated in the publication of the first edition of “Limits of Oceans and Seas,” following a decision by the 1929 Monaco Conference of the International Hydrographic Organization (IHO). This book, which has since been used by cartographers all over the world as an authoritative reference for the designation of maritime features, employed the term “Sea of Japan” for the body of water in question. Yet, at that time under Japanese colonial rule, Korea was deprived of its sovereignty, and had no diplomatic representation on the global stage.
Apart from the historical validity of the use of the 'East Sea,'it is inappropriate to name a sea area surrounded by many countries after a single country. Lying between Korea and Japan and extending north toward Russia, the body of water in question is divided into either the territorial waters or Exclusive Economic Zones (EEZs) of the countries encircling it. There is no possible justification for naming the sea area after one particular country without the consent of the other surrounding countries.
Pending a final agreement on a common name for the sea in question, the Republic of Korea is of the view that, as an interim measure, both “East Sea” and “Sea of Japan” should be used simultaneously. Indeed, the International Hydrographic Organization (IHO) and the UN Conference on the Standardization of Geographical Names (UNCSGN) resolutions endorse the principle of the simultaneous use of different names when countries sharing a geographical feature do not agree on a common name.
The concurrent use of both names by many internationally respected mapmakers is a clear indication that they fully accept the legitimacy of Korea's claims and have decided to endorse the relevant resolutions of the IHO and the United Nations.
Given the historical background of this sea area and the general principles and practices of international cartography, the Korean government calls for the names “East Sea” and “Sea of Japan” to be used simultaneously until agreement on a single name is reached.