Kyodo via Reuters, file

The disputed islands known as Senkaku in Japan and Diaoyu in China that Japan claimed are an integral part of their territory in new teaching manuals.

By Arata Yamamoto and Henry Austin, NBC News

TOKYO -- Japan risked further irking their close neighbors China and South Korea on Tuesday, when the government announced textbooks were being changed to make it clear that two sets of remote islands at the center of sovereignty disputes are integral parts of their territory.

Education Minister Hakubun Shimomura said the ministry was revising the teaching manuals so junior high and high school students learn "properly" about Japanese history and to make it clear that there is no dispute over the ownership of the rocky Senkaku islands in the South China Sea.

The island chain that China calls the Daioyus, have been a flash point between the two countries since Tokyo nationalized the group of uninhabited archipelagos in 2012.

China claims almost all the South China Sea and in November announced it was expanding its air defense identification zone to include the disputed islands.

A few days after they began to enforce this, American bombers flew over the islands on what was described as a training mission.

South Korea summoned the Japanese ambassador on Tuesday to protest claims to the Takeshima islets, known as Dokdo in South Korea. They are situated most equidistant between the two countries.

"Our government strongly condemns this and asks Japan to immediately withdraw it," Seoul, who haveadministered the islets since the end of World War II, said in a statement.

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Disputed islands are ours, Japan's textbooks claim