The United States has urged Beijing to scrap new aviation arrangements set up by its new air defense zone which Washington has denounced as confusing and likely to increase the risk of accidents.
"Our general position as a US government is that we don't accept China's requirements," State Department spokeswoman Jen Psaki reiterated.
Last month Beijing declared an Air Defense Identification Zone, or ADIZ, over the East China Sea, including an island chain disputed with Japan, in which it warned all aircraft had to obey Chinese orders or face unspecified "defensive emergency measures".
But Psaki slammed the announcement as having been made without "prior consultations," adding that it overlapped with many other such zones set up by Japan and South Korea.
"The fact that China's announcement has caused confusion and increased the risk of accidents only further underscores the validity of our concerns and the need for China to rescind the procedures," she told reporters.
"This announcement is not going to change our military exercises," she insisted, pointing to an overflight of two American B-52 bombers in the air last week which was not notified to the Chinese authorities as proof.
The Federal Aviation Administration is tasked with setting guidelines for commercial airlines in the area, Psaki stressed.
But in a statement last week, the State Department said the government in general expects "US carriers operating internationally will operate consistent" with notices sent out by other countries.
US Vice President Joe Biden is to meet Japanese leaders today, after arriving in Tokyo on the first leg of an Asian tour which will also take him to Beijing and Seoul.
White House spokesman Jay Carney said the United States remained "deeply concerned" about China's new air defense zone.
"This is an opportunity for Vice President Biden to raise our concerns directly with policymakers in Beijing and to seek clarity regarding the Chinese intentions in making this move at this time," Carney said.
Biden would underscore "how important it is to avoid actions that raise tensions and to prevent miscalculations that could undermine peace, security and prosperity in the region," he added.
