China and its armed forces have the "confidence, capability" and unwavering determination to defend the Diaoyu Islands, the Defense Ministry said on Thursday.

A think-tank member visiting Beijing also warned that the frequent defense collaboration of the US-Japan alliance has strained the atmosphere of the Asia-Pacific region, and the weakened strategic mutual trust of the US-Japan-China trilateral ties is in "desperate need" of crisis management.

Defense Ministry spokesman Geng Yansheng said at a monthly news conference that the Chinese military is closely watching Japan's moves. "We are against any words or deeds that would escalate or complicate the situation," he said.

While commenting on a recent US-Japan joint island drill in the western Pacific Ocean that reportedly "targets China", Geng said Beijing firmly opposes any deeds that may increase tension in the region.

Safeguarding the security, peace, and prosperity in the region is in everyone's interests, Geng said.

Cai Yingting, deputy chief of the General Staff of the Chinese People's Liberation Army, also reiterated China's stance over the Diaoyu Islands during his recent visit to the US.

During a Wednesday news briefing, US State Department spokeswoman Victoria Nuland was asked whether the US supports Japan's rival territorial claim over the Diaoyu Islands, which belong to China.

Nuland said that the US does not have a position on the sovereignty of the islands, yet she reiterated that the US see the islands "falling under the scope" of Article 5 of the 1960 US-Japan Treaty of Mutual Cooperation and Security, a defense pact that promises Washington's needed support to help Japan protect its "territory".

Geng also confirmed that US Defense Secretary Leon Panetta will visit China in mid-September, but did not provide the exact date.

Observers stressed the possible influence of Panetta's visit to the tensed situation in the East China Sea.

Stephanie Kleine-Ahlbrandt, a researcher and the North East Asia project director of the think tank International Crisis Group, showed concern over the vulnerability of Sino-US strategic mutual trust in addition to the mistrust between China and Japan.

"As its relationship with China entered an uncertain period, Japan sought to strengthen ties with the United States, fueling anxiety in Beijing that the US-Japan alliance could be an effort to contain China's growing power," she said in a seminar co-hosted by the Chinese Academy of Social Sciences and the Tokyo Foundation.

She also warned the increasingly dangerous role of nationalist moods in shaping foreign policies of both China and Japan in recent incidents concerning the Diaoyu Islands.

Akio Takahara, a professor of contemporary Chinese politics at the University of Tokyo, warned that the nationalist mood "has gathered momentum" in all three countries.

"Reining in the irrational mood is a major common task for the three countries," Takahara said.

Also at the news conference, Geng refuted the accusation of an article published by The Washington Post on Aug 26, which said China's surging exports of cheap assault rifles and ammunition to sub-Saharan Africa over the past decade fueled regional military conflicts there.

Geng said China's arms export volume is "very limited compared with US", and China strictly follows relevant UN treaties and established a comprehensive legal and management system for arms exports.

Contact the writers at zhangyunbi@chinadaily.com.cn and qinzhongwei@chinadaily.com.cn