The head of South Korea's police on Tuesday visited a pair of South Korea-held islets in the Sea of Japan claimed by Japan, a source close to the police said.

Kim Chang Yong, commissioner general of the National Police Agency, flew to the territory, known as Dokdo in South Korea and Takeshima in Japan, in what local media said was the first visit by an incumbent police agency chief in 12 years.

Photo taken in April 2005 shows one of the South Korea-controlled Dokdo islets, known as Takeshima in Japan. (Getty/Kyodo)

The visit was reportedly aimed at offering encouragement to police officers who are stationed there.

South Korean senior officials and lawmakers have visited the islets as a way to reassert South Korea's territorial sovereignty over them.

A lawmaker of the main opposition People Power Party went to there on Aug. 15, the 76th anniversary of Japan's surrender in World War II in 1945, which ended Tokyo's 35-year colonial rule of the Korean Peninsula.

In responding to Kim's visit, Japan's Chief Cabinet Secretary Hirokazu Matsuno told a press conference that Tokyo has lodged a protest with the South Korean government, stressing the islets are an "inherent part" of Japanese territory.


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