South Korea's defense ministry on Monday flatly dismissed Japan's renewed territorial claims to the country's easternmost islets of Dokdo, saying Seoul does not even have to repeat explanations on the matter.

Last week, the Japanese government approved 296 textbooks for first-year high school students, including 30 kinds for social studies subjects, which contain Tokyo's sovereignty claims to Dokdo.

"I think it needs no explanations, but Dokdo is South Korea's inherent territory historically, geographically and by international law. The defense ministry maintains such a stance," ministry spokesperson Boo Seung-chan told a regular briefing in an answer to a reporter's question.

Relations between Seoul and Tokyo have fallen to one of the lowest ebbs in recent years, as historical and diplomatic spats have spilled over into economic and security realms, though the two sides have been working to improve ties amid US calls for stronger trilateral security cooperation.

The ministry has said that it is working to separate military issues from non-military matters.

As for the envisioned "two plus two" foreign and defense ministers' meeting with China, Boo said the defense ministry will actively engage in such dialogue.

On Saturday, South Korean Foreign Minister Chung Eui-yong held talks with his Chinese counterpart, Wang Yi, and agreed to seek to hold a 2+2 dialogue in the first half of this year.

"The meeting could serve as a chance to boost communication and cooperation. We will actively engage in the dialogue," Boo said.

Asked about any unusual moves by North Korea at the Yongbyon nuclear facilities or Sinpo shipyard, the ministry said the authorities "are closely monitoring North Korea in close cooperation with the US, but there is nothing special that deserves explanations as of now."

There have been reports that signs have been detected that North Korea resumed operations of the nuclear facilities, and it may be working to launch a new ballistic missile submarine soon. (Yonhap)