U.S. challenges China air defense zone over disputed island Share This: UPI 11/26/2013 5:19:31 PM WASHINGTON, Nov. 26 (UPI) -- Two unarmed U.S. B-52 bombers flew over a disputed island in the East China Sea, challenging China's expanded defense zone, The Wall Street Journal reported. The bombers were not accompanied by jet fighters. China said during the weekend it was expanding its Air Defense Identification Zone. The Journal said U.S. Defense Department officials earlier said the United States would challenge the zone and not comply with China's requirements to file a flight plan, transponder information or radio frequency. A U.S. official said the planes flew out of Guam and penetrated the air defense zone at 7 p.m. EST, and the flight was part of a planned military exercise called Coral Lightning. The island is part of a group that is a growing source of friction between China and Japan. The Chinese claim the islands, which they call the Diaoyu Islands. Japan claims the same group, calling them the Senkaku Islands.