Territorial rivalry
In November, China announced the creation of the East China Sea Air Defense Identification Zone, which requires aircraft to report their flight plans and establish identification communications while flying through the zone.
More than 20 countries, including the United States and Japan, have set up their own air defense identification zones since the 1950s.
The move by China has drawn criticism from the US and its ally Japan, given that the zone encompasses the Diaoyu Islands, which China has owned for centuries but which were "nationalized" by Tokyo in 2012.
Japan's illegal purchase triggered strong protests from China and prompted it to start regular patrols around the islands last year. In July, five PLA warships steamed out of the Sea of Japan, through the Soya Strait and completed the Chinese navy's first circumnavigation of the Japanese archipelago.
Cao Weidong, a researcher at the PLA Naval Military Studies Research Institute, said such activities would not increase tensions and that China's stance remains defensive, while its naval forces are still dwarfed by traditional maritime powers.
"Instead, Washington is shifting 60 percent of its warships to the Pacific and Tokyo is gearing up to build a fully fledged military. China is suffering from the threat of escalating conflict," he said.
James Holmes, a maritime strategist at the US Naval War College in Newport, Rhode Island, and a former US Navy surface warfare officer, said, "Naval commentators suggest the bellicose rhetoric shows that both sides are struggling to adjust to their new rivalry.
"And, the Japanese do regional tranquility no service by being alarmed when China's navy transits international straits in a perfectly lawful manner," Holmes told Reuters.
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