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China is trying to strengthen its claim on tiny, uninhabited, Japanese-controlled islands by raising questions about the much larger Okinawa chain that is home to more than a million Japanese along with major U.S. military installations. The tactic, however, appears to have done little but harden Tokyo's stance.

Japan refuses to offer any concessions to China over Tokyo's control of the uninhabited East China Sea islands, which are called Diaoyu by China and Senkaku by Japan. Tokyo issued a formal protest to Beijing over the comments about Okinawa, made in last week in the ruling Communist Party's flagship newspaper, the People's Daily.

Scholars in Japan and elsewhere, meanwhile, warn Beijing may be shooting itself in the foot by arousing fears of a creeping campaign to nibble away at Japanese territory.

"If China's goal is to hold talks with Japan over the Senkakus, articles like these are counterproductive," said M. Taylor Fravel, a Chinese foreign policy expert at the Massachusetts Institute of Technology. "As a result, Japan has an even stronger incentive now to stand firm with China and not hold talks."

The Diaoyu issue has rarely been out of the headlines in China since Japan's government bought the islands in September to preempt Tokyo's pugnacious former mayor from doing so.

Although the Japanese government purchase was ostensibly aimed reducing tensions, the move was seen in China as an attempt to solidify Tokyo's sovereignty over the islets. Outraged Chinese staged violent street protests and attacked Japanese property, while the government backed up its objections by dispatching patrol boats to confront Japanese ships and sending a surveillance plane into Japanese airspace. While the sides have avoided clashes, the situation remains tense and neither side has backed down.

The comments about Okinawa appeared in a scholarly editorial in People's Daily, in an apparent attempt to weaken the historical basis of Japan's claim to the Senkaku islands by questioning the legitimacy of its control over the entire Okinawa chain. Its authors, Li Guoqiang and Zhang Haipeng, are prominent academics at the government's Chinese Academy of Social Sciences and the editorial is believed to have received high-level approval.

Li and Zhang wrote that Japan's annexation of the formerly independent kingdom of the Ryukyus, including Okinawa, in 1879 amounted to an invasion and the question of sovereignty remains open. The kingdom had also been a Chinese vassal, giving Beijing a say in its political status, although the ruling Qing dynasty was too weak at the time to oppose Japan, the two wrote.

"Not only is Japan obliterating the truth about the Ryukyu issue, but it is doubling its aggressiveness and making provocations over the Diaoyu issue. Therefore it is necessary to revisit the Ryukyu issue," Li wrote in a follow-up article in a sister newspaper, Global Times. Neither scholar said what, if anything, China should do about the Okinawa chain.

Japan added the Senkaku islands to its territory in 1895, but China refuses to consider them a part of Okinawa. It claims that they were always part of Taiwan, the self-governing island claimed by Beijing.

Japan's Chief Cabinet Secretary Yoshihide Suga said last week that the Chinese remarks about Okinawa were "totally unacceptable to us."

China's increasingly combative stance is seen as reflecting the attitudes of the country's new leader Xi Jinping, who espouses a muscular nationalism and an aggressive approach to China's territorial claims. China has sparred with the Philippines and Vietnam over overlapping claims in the South China Sea and recently engaged in a three-week standoff with Indian troops along a remote Himalayan section of their disputed border.

China's navy and air force have also been increasingly active around Okinawa, passing through on their way to the West Pacific and conducting missions over the East China Sea that regularly force Japan to scramble its own jets.

The Chinese assertiveness has prompted a rebalancing of forces to the Asia-Pacific region by the U.S., which already maintains Air Force, Marine, Navy and Army bases on Okinawa, along with about 25,000 troops. Although Washington doesn't take a formal stance on the Senkakus' sovereignty, it recognizes Japanese control over them and says they fall within the scope of the U.S.-Japan mutual defense pact.

Washington's stance has drawn rebukes from Beijing, which already resents the U.S. for emboldening Japan on the issue and is highly criticial of what is referred to as the American military's "pivot" to Asia.

The U.S. rebalancing "has aroused a great deal of suspicion in China," former Vice Foreign Minister He Yafei wrote in Foreign Policy magazine this week. "These suspicions deepen when the United States gets itself entangled in China's dispute with Japan over the Diaoyu islands," He wrote.

Liang Yunxiang, a Japan expert at Peking University, said China's questions about Okinawa are in part intended to win over global public opinion by "raising awareness of Japan's invasion history that Japan has tried so hard to obscure."

However, Liang said that "the move will, of course, frustrate Japan and the stances of the two sides may get tougher."

Beijing will likely take further such moves as part of a calculated strategy to increase pressure on Japan and strengthening China's bargaining position, said Paul O'Shea of the Center for East and Southeast Asian Studies at Sweden's Lund University.

June Teufel Dreyer, a China expert at the University of Miami, said the danger for Beijing is not only that it could alienate Japan, but that it could raise expectations among Chinese activists. That could make it harder for the government to back away from the issue, posing the "first serious test of Xi Jinping's leadership abilities," she said.

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AP writer Elaine Kurtenbach in Tokyo contributed to this report.