U.S. airlines were told by the State Department to notify Chinese authorities before flying through China's new air-defense zone, even as the American military conducts daily flights in the area without such notification.
While U.S.-based carriers should meet China's requirements for flying through the area, the recommendation doesn't mean the Obama administration accepts China's assertion of the zone, the department said Friday.
"Freedom of overflight and other internationally lawful uses of sea and airspace are essential to prosperity, stability and security," the agency said, repeating U.S. concern over China's assertion of the air-defense identification zone.
The advisory to carriers came as Japan raised the dispute over the zone at a meeting of the International Civil Aviation Organization in Montreal. A Japanese government representative told the UN agency the zone could threaten the order and safety of international aviation and requested a review, according to the country's foreign ministry.
The State Department's notice emerged hours after the U.S. military disclosed that it has been flying daily through the disputed area without providing notice to Beijing.
The disclosure Friday by a U.S. defense official indicates U.S. flight activity in the area, where China has sought to exert control, is more extensive than was previously known.
"It's very important the U.S. signal to the Chinese that we're not going to be bullied and that we're going to adhere to our commitments," which include a defense treaty with Japan, said Nicholas Burns, a former undersecretary of state for political affairs.
The Pentagon had acknowledged a flight by two unarmed B-52 bombers through the zone last week. The defense official, who asked not to be named discussing military operations, wouldn't specify the type of aircraft used in subsequent flights or say whether any of them were armed.
China for a second day sent fighter planes into the zone over an area that includes islands claimed by both China and Japan. The situation "holds the real potential for a crisis," said Dean Cheng, a senior research fellow at the Asian Studies Center of the Heritage Foundation in Washington.
China announced the air-defense identification zone effective Nov. 23 and said its military will take "defensive emergency measures" if aircraft enter the area without reporting flight plans or otherwise identifying themselves.