China scrambled military jets and accused Japan of "unscrupulous" behaviour while fingering its Asian rival as the "prime target" of a new air sovereignty zone it established with little warning last Saturday in a move that has substantially heightened the jostling between the two nations.

"Maybe an imminent conflict will be waged between China and Japan," the Communist Party-run Global Times warned in an editorial on Friday, the same day the Chinese military launched aircraft to identify two U.S. and 10 Japanese planes. The newspaper, an arm of the People's Daily and widely viewed as a mouthpiece for official China, disclosed the country's readiness to "firmly counter provocative actions from Japan" and "carry out timely countermeasures without hesitation" if Japan refuses to abide by rules Beijing has imposed in its air defence identification zone.

Last Saturday, China abruptly declared the zone over a vast stretch of its maritime area, including over the islands – known as Diaoyu in China and Senkaku in Japan – whose ownership the two countries fiercely dispute. China now requires aircraft entering the zone to identify themselves, although at the direction of Tokyo, Seoul and Washington, some airlines and military flights have deliberately flouted that requirement.

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On Friday, in a move aimed at assuaging worries from friendlier countries, China specifically exempted aircraft from the U.S., South Korea and Australia – all of which have publicly denounced the new zone – from being targeted, providing they do "not go too far."

It stood resolute on Japan, however, with the Global Times pledging willingness for "a protracted confrontation with Japan. Our ultimate goal is to beat its willpower and ambition to instigate strategic confrontation against China."

The heightened tension between China and Japan comes as U.S. Vice-President Joe Biden prepares to come to Japan, China and South Korea next week in a visit almost certain to be overshadowed by fallout from the new air zone. U.S. officials portrayed the visit as a chance to help defuse tensions, which are growing across the region. On Friday, South Korea moved to extend its own air defence identification zone over a submerged maritime rock whose ownership it contests with China.

And the U.S. is hardly a neutral party. It has sided with Japan, and its own surveillance flights near China's coast have themselves long prompted protests from Chinese officials. Japan has its own air defence identification zone of the area, prompting accusations of duplicity from China.

As the geo-strategic game of chicken plays out, it is likely to undermine other efforts to bring calm to the region, said James Manicom, a global security research fellow at the Centre for International Governance Innovation in Waterloo.

Mr. Biden "could have gone there and tried to build confidence between South Korea and Japan, and tried to build bridges between Japan and China. But that's out of the question now," he said.

While Mr. Manicom called a military escalation very unlikely, he said the risk of an aerial accident is real, particularly in coming weeks as both nations assert themselves with little established protocol between them.

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"States engage in brinksmanship. In some ways, this is quite reminiscent of the Cold War – and a big part of that was about regulating the interaction between Russian and U.S. jets when they would be by each other at various corners of the world."

The visit with Mr. Biden may offer China an opportunity to "clarify" its intent for the new air zone, thereby bringing down the temperature, said M. Taylor Fravel, a member of the Security Studies Program at MIT.

"If China adopts practices used by other countries, then the potential for escalation will decrease. China, however, is unlikely to change the size of the zone," Mr. Fravel said.

For now, Beijing has shown little appetite for cooler rhetoric. While the Global Times acknowledged China has "encountered difficulties in the nascent stage" of its new air zone, it at the same time sounded a martial drumbeat.

"If the trend continues, there will likely be frictions and confrontations and even tension in the air like in the Cold War era between the U.S. and the Soviet Union," the newspaper wrote. "It is therefore an urgent task for China to further train its air force to make full preparation for potential conflicts."

China accused Japan of "unscrupulous" behaviour while fingering its Asian rival as the "prime target" of a new air sovereignty zone it established with little warning last Saturday. Below is a map of the new zone.

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