Analysts said Japan's effort to involve the United States in its rival claim over China's Diaoyu Islands shows "its lack of bargaining power", and its domestic political chaos and contradictory remarks are stirring up frictions over the islands.

Like his predecessors, Japanese Foreign Minister Koichiro Gemba has made repeated calls on Washington to take a position on the Chinese islands and affiliated islets in the East China Sea.

Gemba even told the Japanese House of Representatives on Tuesday that he had confirmed with US Secretary of State Hillary Clinton that the islands "fall within the scope" of the US-Japan Treaty of Mutual Cooperation and Security, an agreement symbolizing Washington's commitment to necessary security support.

However, Washington has not responded yet to the remarks, and Beijing on Wednesday slammed Gemba's remarks with "great concern and firm opposition".

"Any private deals made between the United States and Japan after World War II concerning the Diaoyu Islands are illegal and invalid," the Chinese Foreign Ministry said in a written reply.

The treaty should not undermine the interests of third parties, including China, and Beijing hopes "countries concerned can contribute more to regional peace and stability".

Gao Hong, a Japanese studies researcher with the Chinese Academy of Social Sciences, said Japan's repeated resorts to Article 5 of the US-Japan treaty shows a lasting shortage of bargaining power to back Tokyo's claim. Washington will not sacrifice US-China ties over the territorial issue, he added.

"The US will not commit itself to a major conflict with China, and mainstream Japanese opinion also places few bets on the possibility of US military support to the islands claim," Gao said.

Washington refuses to take a position on the islands, Patrick Ventrell of the US State Department said.

"We've clearly stated our policy on the issue of these islands," Ventrell said on July 16.

In addition to calling for help from other parties, some Japanese politicians and media organizations have sent vague or differing signals over the islands that have embarrassed the Japanese government, which again reflects the prevailing chaos in the Japanese political arena, analysts said.

While addressing the House of Representatives on Wednesday, Japanese Prime Minister Yoshihiko Noda did not respond directly to a request by some congressmen to land on the islands in mid-August to "commemorate deaths during World War II".

Noda reiterated the Japanese government's ban on landing on the islands, yet he said the claimants' feelings "should be given serious respect" and his cabinet will make a decision on the request after consideration, Japan's Sankei Shimbun newspaper reported.

The prime minister started pushing for "nationalizing" the islands in early July, and now he and his cabinet are trapped in the dilemma of being pressed hard by both supporters and antagonists, analysts said.

"Noda knows the landing will lead to a major friction with China, yet domestic political pressure is asking him to be tough because nationalist forces are gaining momentum in Japan," said Yang Bojiang, a professor of Japanese studies at the University of International Relations in Beijing.

Yang also said Noda's current attention is focused more on pushing reform within the House of Representatives than the islands.

Japanese Defense Minister Satoshi Morimoto's remarks on July 19, which support the Tokyo prefectural government's plan for landing on the islands, also reflect chaotic opinions in Japan.

"I wonder if it's appropriate to reject it,'' he told reporters, saying he will support granting permission if the prefectural government follows the necessary application procedures, Kyodo News Agency reported.

As an official denial, Japanese Cabinet Secretary Osamu Fujimura said on Monday that the remarks are not within the scope of the defense minister's duty. He stressed that Morimoto only expressed his "personal opinion".

Chaos features in contemporary Japanese politics, and the differing voices stem from various domestic interest groups, said Gao.

Yang said conflicting positions are common among Japanese politicians because the country has not clarified its strategy on China, and the senior officials' opinions remain far from unified.

zhangyunbi@chinadaily.com.cn