With the territorial dispute between the two countries over the islands in the East China Sea deteriorating, Japan's Deputy Foreign Minister Akitaka Saiki Tuesday summoned Chinese Ambassador Cheng Yonghua to protest four Chinese surveillance vessels staying in the waters off the islands for more than 13 hours earlier this week.
Earlier, Japan's chief government spokesman Yoshihide Suga had described the Chinese action an "extremely unusual incident and very regrettable."
The uninhabited islands reportedly rich in energy resources, which Japan has administered for decades, are also claimed by China, which calls them Diaoyu Islands. Tensions have risen sharply since last September when Japan nationalized the islands, leading to violent protests in Chinese cities, boycott of Japanese goods, and prompting Beijing to send its vessels to assert its claims.
Ambassador Cheng rejected the protest from Japan, China Daily reported Wednesday, while noting relations between the two countries "have sunk to their lowest level in years since the Japanese government illegally 'purchased' part of the Diaoyu Islands in September."
The report said the islands belong to China and "have been Chinese sovereign territory for centuries."
Separately, Chinese Foreign Ministry spokesman Hong Lei described its patrols as regular missions conducted for administrative purposes.
Li Xiushi, a researcher on Japanese studies at the Shanghai Institutes for International Studies, told China Daily said the lack of trust between Tokyo and Beijing may further damage economic ties.
Two-way bilateral trade, estimated at about $350 billion annually, already has been adversely affected by the dispute.
On Tuesday, China also accused Japan of scrambling its fighter jets to "violate the islands' airspace and letting its vessels enter China's territorial waters off the islands."
In a separate article Wednesday, China Daily accused Japan's new government led by Prime Minister Shinzo Abe of wasting "no time in seeking to hem in China diplomatically" as Japan's new Foreign Minister Fumio Kishida Wednesday prepared to visit to Southeast Asia and Australia.
The newspaper quoted experts that the trips to eight countries planned by Abe and his key Cabinet members this month "have sent a clear signal that the officials intend to rein in China."
The sweeping trips in the region has shown Tokyo's triple geopolitical pursuits including local natural resources, navigation freedom, and the encirclement of China, Yang Baoyun, an expert on Southeast Asian studies at Peking University, told China Daily.
The report cited Japan's Deputy Prime Minister and Finance Minister Taro Aso's last week visit to Myanmar, where he offered low-interest loans and promised to write off Myanmar's overdue debt.
Lu Yaodong at the Chinese Academy of Social Sciences told the newspaper Japan will enhance ties mainly with those countries that have rival territorial claims against China in the region.
"Seeking more political and defense support tops Tokyo's diplomacy with the Southeast Asian countries, and in addition to its pragmatic pursuit, Tokyo is yearning for more potential to tap into the market there compared to Aso's visit to Myanmar," Lu said.
The article said the Abe Cabinet's top priority is to boosting the traditional U.S.-Japan alliance. Yang Baoyun of Peking University said Tokyo and Washington also "have been utilizing each other in the region as part of Washington's pivot-to-Asia strategy."
"Tokyo knows that it cannot confront Beijing directly, and that's why it depends on its alliance with the U.S. while seeking any regional players that it can collaborate with, including Australia and some ASEAN countries," Liu Jiangyong, an expert on Japanese studies and the deputy dean of the Institute of Modern International Relations at Tsinghua University, told the newspaper. ASEAN stands for the 10-member Association of Southeast Asian Nations.