By Phil Stewart and David Alexander
WASHINGTON (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 on Tuesday to resolve its dispute with Japan over the islands diplomatically, without resorting to "threats or inflammatory language."
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.
The zone covers the skies over islands at the heart of a territorial dispute that China has with close U.S. ally Japan.
"The policy announced by the Chinese over the weekend is unnecessarily inflammatory," White House spokesman Josh Earnest told reporters in California, where President Barack Obama is traveling.
"These are the kinds of differences that should not be addressed with threats or inflammatory language, but rather can and should be resolved diplomatically," he said.
Two U.S. B-52 bombers carried out the flight, part of a long-planned exercise, on Monday night EST, 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 down the road, said Dean Cheng, an analyst at the conservative Heritage Foundation 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.'"
The B-52s, which have been 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, using the Japanese name for the islands.
The dispute 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 will figure prominently on Biden's agenda.
While Washington does not take a position on the sovereignty of the islands, it recognizes that Japan has administrative control over them and is therefore bound by treaty to defend Japan in the event of an armed conflict.
The Pentagon said the training exercise "involved two aircraft flying from Guam and returning to Guam." Warren said the U.S. military aircraft were neither observed nor contacted by Chinese aircraft.
The United States and Japan have sharply criticized China's airspace declaration, with U.S. Defense Secretary Chuck Hagel calling it a "destabilizing attempt to alter the status quo in the region." He said on Saturday the United States would not change how it operated there.
The Chinese move was believed to be aimed at chipping away at Tokyo's claim to administrative control over the area, including the tiny uninhabited islands known as the Diaoyu in China.
Japan's two biggest airlines - Japan Airlines and ANA Holdings - bowed to a Japanese government request to stop complying with the Chinese demands for flight plans and other information. They will stop providing the information on Wednesday, spokesmen for the carriers said.
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.
In addition, China sent its sole aircraft carrier on a training mission into the South China Sea on Tuesday amid maritime disputes with the Philippines and other neighbors and tension over its airspace defense zone.
It was the first time the carrier was sent to the South China Sea.
(Additional reporting by Jeff Mason in California, Matt Spetalnick and Lesley Wroughton in Washington, Tim Kelly in Tokyo, Lincoln Feast in Sydney,; Ben Blanchard in Beijing; Megha Rajagopalan, and Manny Mogato in Manila; Editing by Alistair Bell and Peter Cooney)