Days after China asserted greater military control over a swath of the East China Sea to bolster claims to a cluster of disputed islands, the U.S. defied the move Tuesday as it flew two B-52 bombers through the area.

The U.S. said what it described as a training mission was not flown to respond to China's latest military maneuver, yet the dramatic flights made clear that the U.S. will not recognize the new territorial claims that Beijing laid out over the weekend.

The two unarmed U.S. B-52 bombers took off from their home base in Guam and flew through China's newly designated air defense zone, then returned to base, U.S. officials said. The bombers were in the zone for less than an hour, thundering across the Pacific skies during midday there, the officials said, adding that the aircraft encountered no problems.