Vietnam has lodged a formal complaint with the United Nations (UN) over China's placement of a surface-to-air missile battery on a disputed island in the South China Sea.
Vietnam Foreign Ministry said on Friday that these are serious infringements on Vietnam's sovereignty over the Paracels, threatening peace and stability in the region as well as security, safety and freedom of navigation and flight.
The statement said diplomatic notes had been issued to China's embassy in Hanoi and to UN Chief Ban Ki-moon to condemn China's activities.
China claims nearly all of the South China Sea, including small islands such as the Paracels.