China's top newspaper today published a call for a review of Japan's sovereignty over the island of Okinawa -- home to major US bases -- with the Asian powers already embroiled in a territorial row.
The lengthy article in the People's Daily, China's most-circulated newspaper and the mouthpiece of the ruling Communist party, argued that the country may have rights to the Ryukyu chain, which includes Okinawa.
The island is home to major US air force and marine bases as well as 1.3 million people, nearly all of whom are Japanese nationals and speak Japanese.
The authors of the article, two scholars at the Chinese Academy of Social Sciences, considered China's top state-run think-tank, said the Ryukyus were a "vassal state" of China before Japan annexed the islands in the late 1800s.
"Unresolved problems relating to the Ryukyu Islands have reached the time for reconsideration," wrote Zhang Haipeng and Li Guoqiang, citing post-World War II declarations that required Japan to return Chinese territory.
The article also repeated Chinese government arguments for China's historical claims over a set of tiny uninhabited islets in the East China Sea known as Diaoyu in Chinese and Senkaku in Japanese.
The two nations have stepped up a war of words in recent months, with Beijing's vessels regularly entering the waters around the Tokyo-controlled islands, stoking fears of armed conflict.
In Tokyo, Chief Cabinet Secretary Yoshihide Suga dismissed the article as "injudicious".
"They are unmistakably part of our country's territory. That is a fact accepted historically and by the international community," he said.
Questions over Japan's right to Okinawa were probably aimed at raising the stakes in the East China Sea dispute, said Willy Lam, an expert on Chinese politics at the Chinese University of Hong Kong.
"I think this is psychological warfare," he said.
"The major point is to put pressure on Japan so that the Japanese administration will be forced to make concessions over the Senkaku islands."
Chinese foreign ministry spokeswoman Hua Chunying repeatedly refused to give a direct answer when asked whether Beijing considers the Ryukyu chain a part of Japan at a regular press briefing today.
"Academics have long paid attention to the history of Okinawa and Ryukyus... But the Diaoyu islands are China's inherent territory, and have never been part of the Ryukyus or Okinawa," she said.