A day after American and Japanese officials voiced concern over China's plan to establish an air defence zone to track aircraft over parts of the disputed East China Sea, China strongly defended its move and hit out at both countries for making "irresponsible" statements on the issue.

On Sunday, U.S. Secretary of State John Kerry and Secretary of Defence Chuck Hagel both voiced "deep concern" over the move, after China said the Air Defence Identification Zone (ADIZ) would include the airspace over the disputed Senkaku or Diaoyu islands in the East China Sea. Chinese authorities will require aircraft to notify them of their flight plans, failing which they could face interception from air defence forces. The zone will not affect international flights, officials said.

The ADIZ overlaps with parts of the zone that Japan has already put in place, raising the likelihood of confrontations between the two countries, which have, in recent months, sparred over their territorial claims.

Mr. Kerry described China's "unilateral action" as "an attempt to change the status quo in the East China Sea" that "will only increase tensions in the region and create risks of an incident".

China on Monday responded angrily to his comments, saying the U.S. needed to "immediately correct its mistake and stop making irresponsible accusations against China".

Foreign Ministry spokesperson Qin Gang told reporters Assistant Foreign Minister Zheng Zeguang had made "solemn representations" with the U.S. Ambassador in Beijing, Gary Locke.

"The U.S.," Mr. Qin said in a statement issued late on Sunday night, "should keep its words of not taking sides on the issue concerning the sovereignty of the Diaoyu islands and stop making improper comments".

In a separate statement, Mr. Qin said China had disregarded Japan's objections, saying it was "unreasonable and completely wrong for Japan to make irresponsible accusation[s]."

Many countries, from the U.S. and India to Japan, have set up ADIZ areas beyond their frontiers to track and monitor aircraft that are headed towards their territorial airspace.

However, the timing of China's move, amid territorial disputes with Japan, has raised concerns that tensions may be escalated.

At a briefing on Monday, Mr. Qin defended the move, saying it was "based on the need for China to defend its national sovereignty and security of China's territory and airspace".

China, he added, will "in due course" announce whether it planned to set up zones across its other contested frontiers. China faces territorial disputes with India in the west, and also maritime disputes involving at least 10 countries over the South China Sea.

Mr. Qin said it was "unreasonable" for Japan to object to the move. Chinese officials have pointed out that Japan set up its ADIZ as early as in 1969, which, like China's zone, extends up to 130 km away from China's territory.

He acknowledged that the two zones had "some overlapping areas", and said China "hopes that the relevant country can enhance communication to jointly maintain regional peace and security".

Japan is not the only country in the region that has voiced concern over the move. South Korea on Sunday said the ADIZ also overlaps with parts of its zone.

Whether or not the moves may increase the chance of confrontation will depend on the rules of engagement that China sets up, M. Taylor Fravel, a professor at the Massachusetts Institute of Technology who is an expert on China’s relations with its neighbours, told The Hindu.

In recent months, Japan has scrambled jets after Chinese Unmanned Aerial Vehicles (UAVs) were deployed over the contested islands. On the waters, too, coast guards and marine surveillance vessels from both countries have had run-ins as both sides look to enforce their claims.

"An ADIZ is a air traffic control zone in international airspace, not national airspace,” Mr. Fravel said. “So, whether it will increase conflict depends on what rules of engagement for intercepting planes that approach the zone without pre-notification. It is probably a response to Japan’s position that it would shoot down UAVs over the territorial airspace of the Senkakus.”

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