Japan's prime minister has called China's declaration of an air defense identification zone that includes the area above disputed islands a dangerous move that could cause serious problems.
Prime Minister Shinzo Abe told a session of parliament Monday that the air defense zone is not enforceable. He added that the measures have no validity whatsoever in Japan and should be revoked.
China announced Saturday new rules that require all aircraft in the zone to identify themselves and obey all commands from Beijing.
China has so far rejected criticism from the U.S. and Japan on Beijing's imposition of the rules.
China's Defense Ministry said Monday that criticism was unfounded and irresponsible. The ministry said it is within the country's rights to set up an air defense zone in the area.
Japan filed a formal protest on Saturday, criticizing China for escalating bilateral tensions over the Senkaku islands, called the Diaoyu islands in China.
White House officials on Sunday called the threat an escalatory development," while Defense Secretary Chuck Hagel called it "a destabilizing attempt to alter the status quo" in the East China Sea. Hagel also said the United States has no plans to change how it conducts military operations in the region.
South Korea jumped into the mix Monday, saying China's air identification zone overlapped with its own and covered a submerged rock claimed by Seoul. South Korea built a research facility on the rock, called Ieodo, in 2003 in an effort to strengthen its claim over the area.