The lynchpin of their argument rest on the claim that the sea was universally known as "East Sea" until 1928, when Imperial Japan registered "Sea of Japan" with the International Hydrographic Organization to show to the world that they controlled "the sea like a lake which was engulfed by Japan and occupied Korea." (There are claim of older European trade maps showing both names but both sides counter each other saying those were provisional cartographic markings or are merely ignored). The Korean e-mail stated that English-language maps labelled the sea as the East Sea up until Imperial Japan forced the name change.
I decided to investigate. Using the Complete National Geographic (let me print full size maps, please!) I was able to find the March 1904 map entitled "Korea and Manchuria" which shows "Japan Sea". This map was made six years before Japan annexed Korea in 1910 and twenty-two years before the claimed 1928 Japanese policy change.
|Japan Sea was used for the body of water 22 years before the alleged 1928 name change. Image courtesy of National Geographic|
The Japanese Government has released official statements that the 1928 claim is bogus. On this point the Japanese are right and pro-Korean forces are wrong.