* No response from China to B-52 bomber flights over new zone
* Japanese airlines stop giving flight details to China
* China has said would take measures against aircraft that don't identify themselves
* Issue on agenda when Vice President Biden visits region next week
* Islands at heart of China territorial dispute with Japan
WASHINGTON/TOKYO, Nov 27 (Reuters) - Two unarmed U.S. B-52 bombers on a training mission flew over disputed islands in the East China Sea without informing Beijing, defying China's declaration of a new airspace defense zone and raising the stakes in a territorial standoff.
The flight did not prompt a response from China, the Pentagon said, and the White House urged Beijing to resolve its dispute with Japan over the islands diplomatically, without resorting to "threats or inflammatory language".
Also defying Beijing, Japan's two biggest airlines - Japan Airlines and ANA Holdings - said they would stop giving flight plans and other information to Chinese authorities from Wednesday when passing through the zone. That followed a Japanese government request, the carriers said.
China published coordinates for an East China Sea Air Defense Identification Zone over the weekend and warned it would take "defensive emergency measures" against aircraft that failed to identify themselves properly in the airspace.
Japan's aviation industry association said it had concluded there was no threat to passenger safety by ignoring the Chinese demands, JAL said. Both JAL and ANA posted notices on their websites informing its passengers of their decision.
The zone, about two thirds the size of Britain, covers the skies over islands at the heart of a territorial dispute that China has with close U.S. ally Japan.
The B-52 bombers carried out the flight, part of a long-planned exercise, on Monday, a U.S. military official said.
The lumbering bombers appeared to send a message that the United States was not trying to hide its intentions and showed that China, so far at least, was unable or unwilling to defend the zone.
Beijing may have been caught off-guard and could change its approach, said Dean Cheng, an analyst at the conservative Heritage Foundation, a Washington-based think tank.
"The Chinese may not have expected such a strong American reaction so soon," Cheng said.
"The fact that Washington responded and responded so strongly sends a very clear challenge back to Beijing saying: 'Look, in case you were wondering, we are serious when we say we are an ally of Japan. And do not mess with that."'
Some experts have said the Chinese move was aimed at chipping away at Tokyo's claim to administrative control over the area, including the tiny uninhabited islands known as the Senkaku in Japan and the Diaoyu in China.
The action might have backfired, said Brad Glosserman, executive director of the Honolulu-based Pacific Forum CSIS.
"This is confirming the darker view of China in Asia," Glosserman said. "The Chinese once again are proving to be their own worst enemy ... driving the U.S. closer to Japan and (South) Korea closer to the position of Tokyo as well."
BIDEN VISITS REGION NEXT WEEK
While Washington does not take a position on sovereignty over the islands, it recognises that Tokyo has administrative control over them and it is therefore bound by treaty to defend Japan in the event of an armed conflict.
The B-52s, part of the Air Force fleet for more than half a century, are relatively slow compared with today's fighter jets and far easier to spot than stealth aircraft.
"We have conducted operations in the area of the Senkakus. We have continued to follow our normal procedures, which include not filing flight plans, not radioing ahead and not registering our frequencies," spokesman Colonel Steve Warren said.
The dispute has flared before a trip to the region by Vice-President Joe Biden, who is scheduled to travel to Japan early next week and also has stops in China and South Korea.
The White House announced the trip in early November. The East China Sea dispute is expected to figure prominently.
The Pentagon said the B-52 training exercise "involved two aircraft flying from Guam and returning to Guam", referring to the U.S. South Pacific island with large military U.S. bases.
Warren said the U.S. military aircraft were neither observed nor contacted by Chinese aircraft.
Annual U.S.-Japan naval exercises are also taking place in waters off the Japanese islands of Okinawa and Kyushu, to the east of China's new zone. The drills, which involve the USS George Washington aircraft carrier, were planned before China's announcement of the zone.
CHINA DEMANDS FLIGHT PLANS
The new Chinese rules mean aircraft have to report flight plans to China, maintain radio contact and reply promptly to identification inquiries and bear clear markings of their nationality and registration.
On Monday, civil aviation officials from Hong Kong and Taiwan said their carriers entering the zone must file flight plans. A transport ministry official in Seoul said South Korean planes would do the same.
Qantas Airways Ltd said on Wednesday its pilots would keep China informed of their flights through the area.
The United States and Japan have sharply criticised China's airspace declaration, with U.S. Defense Secretary Chuck Hagel calling it a "destabilising attempt to alter the status quo in the region".
China's Defense Ministry said it had lodged protests with the U.S. and Japanese embassies in Beijing over the criticism from Washington and Tokyo of the zone.
China also summoned Japan's ambassador, warning Tokyo to "stop words and actions which create friction and harm regional stability", China's Foreign Ministry said. Tokyo and Seoul summoned Chinese diplomats to protest.
While the zone is outside China's territorial airspace, the Chinese Defence Ministry has said its establishment had a sound legal basis and accorded with common international practices.
Other countries including the United States, Japan and South Korea have similar zones but only require aircraft to file flight plans and identify themselves if those planes intend to pass through national airspace.
In addition, China sent its sole aircraft carrier on a training mission for the first time into the oil- and gas-rich South China Sea on Tuesday.
China claims almost the entire South China Sea, conflicting with claims from Taiwan, Malaysia, Brunei, the Philippines and Vietnam.