The Defense Ministry on Friday urged the United States to cease its "irresponsible rhetoric" on issues concerning the Diaoyu Islands and islands in the South China Sea.

At a joint press conference on Wednesday with Japanese Defense Minister Gen Nakatani, US Secretary of Defense Ashton Carter said the Diaoyu Islands "fall within the scope of the 1952 US-Japan Treaty of Mutual Cooperation and Security", and that the United States strongly opposed "unilateral attempts to undermine Japan's administration of these islands".

The information office of China's defense ministry said Diaoyu Island and affiliated islands had been China's indispensable territory since ancient times, a truth that will never change.

"The Chinese government and army is determined to safeguard our territorial sovereignty. The US-Japan alliance is an arrangement made during the Cold War. It should not target a third party, or undermine regional peace and stability," it said.

Carter also expressed concern about China's activities on islands in the South China Sea, saying while the United States does not take any position in territorial disputes, it does take a "strong stand against militarization" of such rows.

The information office of China's defense ministry said China's stance on South China Sea issues was consistent and clear, and that China's activities on those islands was legitimate, thus, other countries had no right to interfere.

"The United States should stop making irresponsible remarks [...] or creating tension," it said.

"The development of China-US military relations is good as the two sides are committed to developing a new-type of military relations. We urge the US side to speak and act cautiously to ensure favorable conditions for healthy and steady development of the relation," the office said.