Vice President Xi Jinping on Wednesday said Japan's "purchase" of the Diaoyu Islands was a farce and urged Japan to stop any behavior that infringes upon China's sovereignty.

"Japan should rein in its behavior and stop any words and acts that undermine China's sovereignty and territorial integrity," Xi said in a meeting with visiting U.S. Defense Secretary Leon Panetta.

It was the first time for Xi to comment on the Diaoyu Islands since the Japanese government announced its decision to "purchase" the Diaoyu Islands on Sept. 10.

He said Japan's "purchase" openly questions the legal effects of the Cairo Declaration and the Potsdam Proclamation and has intensified the neighbors' territorial disputes.

Xi said the international community will never tolerate Japan's attempt to deny the outcomes of the World Anti-Fascist War.

Xi recalled the "September 18 Incident," which directly preceded Japan's invasion of northeast China in 1931, saying Japanese militarism affected not only the Chinese, but also the United States and Asia-Pacific countries.

Rather than reflect on the trauma Japan brought to neighboring countries and some Asia-Pacific countries, Japanese political forces have continued to make mistakes by staging the farce of "purchasing" the Diaoyu Islands, Xi said.

Xi also called on the United States to act in the larger interest of regional peace and stability, mind its words and actions, not to get involved in issues regarding the sovereignty of the Diaoyu Islands and refrain from doing anything that might escalate tensions and complicate the situation.

During a series of meetings with State and military leaders, Panetta reiterated that the United States does not take positions over, what he termed, territorial disputes concerning the islands and called for all sides to be calm and show restraint to avoid confrontation.

Addressing students at the military's Engineering Academy in Beijing on Wednesday, Panetta also sought to convince Beijing that the US strategic "pivot" to the Asia-Pacific region is not to contain China, amid concerns that Washington's increasing presence encourages its allies, like Tokyo, to engage in provocative behavior.

Before arriving in Beijing, Panetta started his weeklong Asia trip with a visit to Japan.

While he was there, Tokyo and Washington agreed to install a second missile-defense radar system and the MV-22 Osprey military aircraft was given the go-ahead to begin flight operations in Japan on Wednesday.

Washington says the Diaoyu Islands fall under the US-Japan security treaty and this is a severe interference in Chinese territorial sovereignty, said Liu Jiangyong, a specialist on Japanese studies at Tsinghua University.