Japan said Sunday it has confirmed a South Korean research vessel conducted a marine survey in waters off disputed islets within Japan's exclusive economic zone in the Sea of Japan.
The ship "Hae Yang 2000" was found to have extended a wire-like object into the sea off the pair of islets without prior consent from Tokyo, according to a statement issued by the Japanese Foreign Ministry.
It said that the South Korean government has admitted to having carried out the survey.
The ministry also said it has lodged protests with top South Korean diplomats about carrying out such surveys within Japan's EEZ without prior consent.
It marks the first time since May 2017 that Japan has lodged a protest with South Korea over a marine survey around Takeshima.
The rocky outcrops controlled by Seoul under the name Dokdo and claimed by Tokyo have long been a source of tension between the two East Asian neighbors, whose ties have also been strained by wartime issues related to Japan's 1910-1945 colonial rule of the Korean Peninsula.
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