Two unarmed U.S. B-52 bombers on a training mission flew over disputed islands in the East China Sea without informing Beijing, Pentagon officials said on Tuesday, defying China's declaration of a new airspace defense zone in the region.

The Pentagon said the flight on Monday night did not prompt a response from China, and the White House urged Beijing to resolve its dispute with Japan over the islands diplomatically, without resorting to "threats or inflammatory language."