China is preparing to conduct combat drills in the South China Sea. The Staff Department of the People's Liberation Army Navy called the exercises routine - and within the navy's annual plan. They will test and improve troops' training and improve capability. Officials from the PLA Navy added the drills are not aimed at any specific country or target. Meanwhile, an American guided missile destroyer entered waters surrounding islands and reefs in the South China Sea - the move provoked a strong response from the Ministry of National Defense.