A US B-52 strategic bomber recently flew near Chinese man-made islands in the South China Sea, the Pentagon said on Thursday.
"We conduct B-52 flights in international air space in that part of the world all the time," Pentagon spokesman Peter Cook told a briefing.
Moreover, the US may be sending secret spy plane over the South China Sea.
The disputed waters have been a point of contention between Beijing and Washington. The United States does not recognize China's claims of sovereignty over the man-made islands.