US Secretary of Defense Leon Panetta is in Beijing for his first visit to China as Pentagon chief, and during his four-day stay, Panetta will hold talks with his Chinese counterpart Liang Guanglie, the Xinhua News Agency reported.

Panetta arrived in Beijing on Monday evening after completing a two-day visit to Japan.

Before he started his journey to Japan, China and New Zealand, Panetta cast himself as a mediator in the dispute between China and Japan over the Diaoyu Islands, Foreign Policy magazine reported.

However, Chinese analysts said that Panetta's visit might promote the Sino-US relationship, but they played down his mediator status.

Shi Yinhong, a professor at the School of International Studies with the Renmin University of China, told the Global Times that China should not accept Panetta as a mediator. "The US worries that if China and Japan fall into a war, it will be harmed," said Shi, adding that Panetta's Japan visit might have included discussions on cooperation in a possible war against China if tensions escalated.

Japan's Foreign Minister Koichiro Gemba told reporters after meeting Panetta on Monday that Tokyo and Washington agree that the disputed East China Sea islets claimed by Japan and China are covered by the Japan-US security treaty, Reuters reported.

"I did not bring up the topic today, but it is mutually understood between Japan and the US that (the islands) are covered by the treaty," Koichiro Gemba said.

In the meantime, the US and Japan agreed on Monday to set up another defense system in Japan's south, officially to protect Japan from the missile threat from North Korea, media reports said.

China hopes the US will stick to its decision not to take a position on the sovereignty of the Diaoyu Islands, foreign ministry spokesman Hong Lei said  Monday.

"As a product of the Cold War, the security treaty is a bilateral arrangement between the two countries, and should not undermine the interests of a third party, including China," said Hong.

"The US will not change its position in the disputes, as that it ostensibly does not take a position, but in fact, it takes the opposite side to China," Jin Canrong, vice dean of the School of International Studies at the Renmin University of China, told the Global Times.

During the talks with Panetta, China will expound its stance on the sovereignty over the Diaoyu Islands, and consider whether Panetta has concrete and acceptable plans to solve the dispute, according to Jin.

"On the Sino-US ties, China should make some gestures in the military exchanges, which would help the US keep its 'neutral' position," Jin said.

Ling Yuhuan and Li Ying contributed to this story